Code of Practice For

Electrical Safety

Guidance for University Departments and Functions

September 2006

Safety Services Office

UNIVERSITY OF LEICESTER

CODE OF PRACTICE FOR ELECTRICAL SAFETY

CONTENTS Foreword Introduction

1.1 General electrical hazards 1.2 Scope of Code 1.3 Framework and application 1.4 Maintenance Section 1.5 Space heaters 1.6 Radiant electric fires

Part A A.1 Commercial electrical equipment

A.1.1 Application A.1.2 Fuses, enclosure, isolation A.1.3 Visual check

A.2 Checks before use

A.2.1 Manufacturer's duties & information A.2.2 Older equipment A.2.3 Equipment taken out or loaned A.2.4 Use of equipment out of doors A.2.5 'Hard use' equipment

A.3 Maintenance

A.3.1 Departmental responsibility A.3.2 Elements of visual check A.3.3 Testing. Frequency, records marking A.3.4 Tests on behalf of Departments A.3.5 Shared equipment

A.4 Summary of Part A

A.4.1 Instructions etc. to users A.4.2 Checks of equipment A.4.3 Maintenance and testing

Part B B.1 Scope of this part of the Code

B.1.1 Application B.1.2 Exceptions and further guidance B.1.3 Installations - general standard B.1.4. Departmental responsibility, contractors B.1.5 Notification to University Engineer

B.2 Electrical apparatus

B.2.1 Commercial equipment B.2.2 Equipment constructed in Departments B.2.3 Minimum electrical safety standards

B.3 Maintenance

B.3.1 Installations - limitation of responsibility B.3.2 Visual checks B.3.3 Further maintenance and testing B.3.4 Advice B.3.5 Testing: Guidance

B.4 Use of electrical equipment in laboratories and workshops

B.4.1 Adverse conditions B.4.2 Conducting fluids B.4.3 Electrical heating equipment B.4.4 Flammable vapours B.4.5 Supply cables, extension leads B.4.6 Hand lamps, machine lamps, low voltage

B.5 Batteries

B.5.1 Fuses, circuit breakers B.5.2 Protection from accidental contact B.5.3 Finger rings B.5.4 Battery charging - ventilation, warning B.5.5 Connecting, disconnecting

B.6 Connection of electrical equipment to humans

B.6.1 Particular hazards B.6.2 Accidental earthing B.6.3 Safe systems of work - Preparation, documentation B.6.4 Further information

B.7 Routine checks of electrical equipment - guidelines

B.7.1 Access to live parts B.7.2 Mechanical damage B.7.3 Cable grip B.7.4 Friction protection B.7.5 Grommets, bushings B.7.6 Connections, fuses B.7.7 Earth continuity B.7.8 Insulation resistance B.7.9 Earth leakage, exceptions to testing requirements, British Standards

B.8 Minimum manufacturing standards

B.8.1 British Standard specifications for electrical safety B.8.2 Commercial and 'in-house' manufacture B.8.3 Earthing B.8.4 Cables, plugs, colour coding B.8.5 Switches, placing, identification B.8.6 Phase disconnections B.8.7 Fuses B.8.8 Isolators, effectiveness, terminals, screening, accidental contact B.8.9 Interlocking switches, construction, placing, maintenance B.8.10 Conductors, terminals. Screening, warning notices B.8.11 Heating elements B.8.12 Liquids. Incorporation, placing. Flammable liquids B.8.13 Fire and explosion. Special equipment. Sparkproof/flameproof fittings B.8.14 Applicable legislation

Part C C.1 Methods of working

C.1.1 Protection of persons C.1.2 Training C.1.3 Risk assessment C.1.4 Work area, layout

C.2 Entry to premises

C.2.1 Authorised persons C.2.2 Supervision, barriers

C.3 Emergency arrangements

C.3.1 Planning C.3.2 Stop buttons, lone working, first aid C.3.3 Electric shock. Instructions, display

C.4 Repairs

C.4.1 Removal of protective covers

C.4.2 Accidental contact C.4.3 Restrictions of work C.4.4 Transformers C.4.5 Earth pathway limitations

C.5 Earth-free areas

C.5.1 Characteristics and guidance C.5.2 Isolating transformers C.5.3 Soldering irons, lighting. Low voltage C.5.4 Barriers. Limitation of occupancy

C.6 Residual current devices (RCDs)

C.6.1 RCDs - function and purpose C.6.2 Advantages and limitations C.6.3 Application to outdoor working

C.7 Repairs in the field

C.7.1 Portable RCDs C.8 Experimental electrical equipment

C.8.1 Temporary rigs, construction C.8.2 Temporary rigs, British Standards C.8.3 Temporary rigs, Wiring diagrams etc. C.8.4 Temporary rigs, Warning of danger C.8.5 Control gear - 415v 3-phase equipment

C.9 Research experimental apparatus above 650V AC/DC

C.9.1 Enclosure of apparatus C.9.2 Security of enclosure

Interlocking Earthing rods Further guidance

Appendix 1: HSC/HSE Publications on electrical safety Appendix 2: Other publications having an electrical safety content

(incl. British and other Standards) Appendix 3: Working space Appendix 4: Guide to the Electricity at Work Regulations 1989

FOREWORD 1. Although electricity causes relatively few occupational accidents, those that do occur

are responsible for a high proportion of deaths. Electrical faults are also the second most frequent cause of fires in industry and commerce in the United Kingdom. The majority of electrical accidents involve equipment that has become defective due to insulation failure, inadequate earthing, incorrect over-current protection (fuses, breakers, etc.) or faulty wiring. These pose a threat to personal safety causing electric shock, burns, explosions and fires.

2. The Electricity at Work Regulations 1989, came into force in all places of work on 1

April 1990. They provide general rules on insulation, cutting off supply, and maintenance of electrical systems, but they do not specify insulation materials nor the design of switches and isolators. Nor do they (contrary to what seems to be a widely held misconception) specify the nature and frequency of maintenance and testing other than to require that maintenance must be such as to prevent danger.

3. The purpose of this Code of Practice is to advise all who use or work with electricity

on practical ways and means of avoiding electrical danger and of complying with the Regulations. The Code is subsidiary to, and forms part of, the University's Statement of Health and Safety Policy and Statement of Organisation and Arrangements prepared and published by the University in compliance with the relevant sections of the Health and Safety at Work Act 1974.

4. The many and varied uses to which electricity is put in the University as elsewhere

are such that no single document can cover all aspects. Lists of further publications covering specific electrical safety topics are appended.

Priced publications can be purchased from the Bookshop. Reference copies of most can be seen at the Safety Services Office by arrangement.

5. Certain parts of the Electricity at Work Regulations have been widely misinterpreted to imply that all existing electrical systems, plant and equipment, are rendered obsolete and must be replaced, regardless of cost, as soon as possible. This is most definitely not the case. The following is abstracted from the Health and Safety Executive's Memorandum of Guidance on the Electricity at Work Regulations 1989 (ISBN 0 7176 1602 9):

"Where electrical equipment pre-dates the Regulations this does not of itself mean that the continued use of the equipment would be in contravention of the Regulations. For example, much of the equipment to which the Regulations apply may have been made to a standard, such as a British Standard, which has since been modified or superseded. It is likely to be reasonably practicable to replace it with equipment made to a more recent standard when, but only when, it becomes unsafe or falls due for replacement for other than safety reasons, whichever occurs sooner. Equally, fixed installations to which the IEE Wiring Regulations are relevant may have been installed in accordance with an earlier edition, now superseded but then current; that in itself, does not means that the installation does not comply with the 1989 Regulations."

CODE OF PRACTICE FOR ELECTRICAL SAFETY 1. INTRODUCTION

1.1 Electricity is widely used throughout the University, and in normal circumstances no hazards should arise. Neglect and misuse of electricity can, however, result in electric shock to individuals, or in overheating, leading to fire.

1.2 This Code of Practice details how Heads of Departments should assess and

implement their arrangements. It forms part of the general University policy on safety and its status is that of good practice that must either be followed or be replaced by equivalent good practice. The Code, or relevant sections (whichever is appropriate) should be incorporated into individual Departmental safety publications.

The nature of electricity is such that no Code of Practice can hope to cover every conceivable aspect of its use. Guidance on specific aspects of electrical safety can be found in relevant British Standards, official publications by the Health and Safety Executive, professional bodies such as the Institute of Electrical Engineers and many other sources.

It is of critical importance, however, that those engaged in work with electricity to any degree should have the necessary level of competence to carry out their work safely. It is also important to bear in mind that ensuring the competence of those working with electricity is a statutory requirement, failure to observe which is a serious offence, carrying with it heavy penalties. The following is extracted from the Health & Safety Executive's official guidance on the Electricity at Work Regulations.

Only those who have both the knowledge and experience to make the right judgements and decisions and the necessary skill and ability to carry them into effect should undertake work subject to this Code. A little knowledge is often sufficient to make electrical equipment function but a much higher level of knowledge and experience is usually needed to ensure safety.

Special note: For convenience, the terms 'Department' and 'Head of Department' are used throughout the code. The term 'Department' should be interpreted to include areas and premises such as student accommodation, offices, shops, grounds and sports facilities and any other place where electricity is used. The term 'Head of Department' should be interpreted to mean the senior member of staff having authority in such areas and premises and, therefore, the responsibility for health and safety under the terms of the University's published policy on the subject.

1.3 The Code has three separate parts, A, B and C. According to

circumstances, Departments will normally need to be concerned with either Part A alone, Part B alone or Parts B and C together.

Part A is for Departments with no technical staff and who use only commercially produced equipment.

Part B is for Departments, who may construct, repair and maintain their own equipment and who will normally have technical staff competent to carry out the recommended maintenance and testing of equipment.

Part C deals with additional hazards, which may arise in Departments who undertake the design, manufacture, repair and testing of electrical apparatus.

1.4 This document is not intended to cover installation and other work by staff of

the Maintenance Section of the Estates Office, who have their own working systems.

1.5 Privately-owned space heaters may not be used in the University. If under

special circumstances the Maintenance Section considers it necessary to provide a space heater, the Section will ensure that it is checked regularly.

1.6 The use of radiant electric fires is specifically prohibited. Their unauthorised

use in the past has been the cause of a number of accidents including life-threatening fires.

CODE OF PRACTICE FOR ELECTRICAL SAFETY PART A A.1 COMMERCIAL ELECTRICAL EQUIPMENT

A.1.1 This part of the Code applies essentially to Departments having no technical staff and who use commercially produced electrical equipment.

A.1.2 Where standard commercial equipment is in use the correct fuse/overcurrent

device should be fitted. Contact with live parts must be prevented by enclosure, isolation or by some other effective means.

A.1.3 The equipment should be visually checked before being put into use to ensure

initial safe condition. A.2 CHECKS BEFORE USE

A.2.1 Manufacturers of any electrical equipment have a legal obligation to ensure that it is safe when properly used. Provided that the correct fuse has been fitted, commercial equipment should be safe without modification. However, instructions given by the manufacturer should be brought to the attention of all users.

A.2.2 When older equipment is brought into use, arrangements must be made to

ensure that it conforms with current safety standards, and that its condition is such that the original built-in safety has not been degraded by wear or misuse. It is the Department's responsibility to check that such equipment is safe to use and in case of doubt, reference should be made to the University Maintenance Section.

A.2.3 This also applies when equipment has been out of the Department on loan or

otherwise. Before being put back into use the Department must ensure that it is in a safe condition.

A.2.4 Equipment to be used out of doors should be fitted with a residual current

device (RCD) to provide optimum protection. In such cases, advice is available from the University Engineer. It should be noted, however, that the use of RCDs cannot be regarded as replacing primary safety features (enclosure, insulation, etc.).

A.2.5 Particular attention is drawn to the high standards of maintenance

needed in respect of 'hard use' electrical appliances. Visual checks of plugs, power cables, connections (at plug and appliance ends) should be frequently carried out and users instructed as to action to be taken if and when unsafe conditions are identified. The term 'hard use' could include:

Vacuum cleaners Floor scrubbers/polishers Horticultural/gardening equipment Mains powered radios/tape players Video recorders Other AV equipment (especially if hired/loaned) Hand-held power tools Extension leads Floor/desk/table/inspection lamps

Portable kitchen appliances Heating mantles Stirrers Soldering irons

and most other equipment which is frequently moved about, plugged and unplugged, or which is subject to added stresses from handling, wet, heat or corrosion.

A.3 MAINTENANCE

A.3.1 It is the Department's responsibility to ensure that its electrical equipment is maintained in a safe condition and that the condition of all appliances is kept under review so as to prevent danger.

A.3.2 The most important arrangement to be made is a visual check of the condition

of the connecting cables and of the plug. The connecting cable must be undamaged and securely fastened both at the appliance end and at the plug ends. The plug must be undamaged and must not rattle, which may indicate loose terminals and potential danger. Check for visual evidence (blackening, scorching, etc.) of arcing or overheating. Any apparent defect must be investigated and remedial action taken.

A.3.3 A full electrical test must be undertaken from time to time. The frequency of

tests depends on the amount, type and conditions of use. A good guide is contained in the HSE leaflet, Maintaining Portable Electrical Equipment in Offices. Records of the test should be kept by the Department, preferably in a register and on the equipment itself by means of a securely attached label, so that the test history can be checked. Such tests should also form part of any repair procedures. (It should be noted that many service contracts will be concerned only with the correct functioning of the equipment and not with its electrical safety).

A.3.4 The University Engineer is prepared to carry out tests on behalf of

Departments with small amounts of electrical equipment who do not have qualified staff available. This will be done at the Department's expense and arrangements should be made directly with the University Engineer's office.

A.3.5 Where equipment is shared by Departments, or is present in accommodation

shared by Departments, specific arrangements must be made to ensure that the equipment is checked regularly.

A.4 SUMMARY

A.4.1 Users should be instructed in the safe methods of use of electrical equipment and should be warned of the hazards of using unsafe equipment.

A.4.2 They should be made aware of the need to make frequent visual checks of the

condition of cables and plugs.

A.4.3 Departments should ensure that electrical equipment is safe to use when installed and remains so by regular checking and maintenance at appropriate intervals. Departments may choose to sub-contract such maintenance but it remains their responsibility to initiate and monitor any arrangement.

CODE OF PRACTICE FOR ELECTRICAL SAFETY PART B B.1 SCOPE OF THIS PART OF THE CODE

B.1.1 This part is applicable to Departments having technical staff competent to make inspections and carry out routine safety checks on electrical equipment.

B.1.2 It does not deal with the precautions to be taken when undertaking repair and

testing of electrical apparatus, or experimental work with electrical equipment. (For this see Part C).

Relevant guidance is included in:

Guidance Note IND(G)236L Maintaining portable electrical equipment in

offices IEE Guidance Code of Practice for In-Service Inspection and

Testing of Electrical Equipment

B.1.3 Electrical systems in buildings up to and including socket outlets (or in the case of permanently installed equipment associated isolators) are normally the responsibility of the Estates Office. Substations housing distribution transformers and switchgear, including cabling and wiring, are the responsibility of the University Engineer. No modification or adaptation may be carried out except through his office.

B.1.4 Departments and sections are normally responsible for installations and

equipment from the socket (or isolator) outwards. Where there is an exception to this rule it must be defined in a formal agreement between the Head of Department or section and the University Engineer. It is particularly important that when Departmental equipment is installed by a contractor, the contract must make it clear where responsibility for electrical safety lies.

B.1.5 The University Engineer should be notified in advance of the acquisition of

any equipment requiring significant amounts of power, to ensure that the necessary supply is available.

B.2 ELECTRICAL APPARATUS

B.2.1 Where standard commercial equipment is in use the primary requirement is that there should be no access to dangerous voltages, i.e. those exceeding 50 volts AC and 120 volts DC. If normal methods of working are adopted this should automatically follow from the standards of construction incorporated by the manufacturer.

B.2.2 The same standards of safety must apply to electrical apparatus constructed

within the University. Prototype equipment must conform in all respects with acceptable standards of electrical safety.

B.2.3 A list of minimum manufacturing safety standards is given in Section B.9.

Before putting into use any electrical equipment, especially apparatus constructed within the University, Departments should check that it conforms fully to these standards.

B.3 MAINTENANCE

B.3.1 The University's responsibility to undertake regular checking of all electrical wiring up to the socket outlets or isolators will be carried out on a regular planned basis by the Estates Office.

It is the Department's responsibility to deal with the safety of all electrical equipment in use in the Department.

B.3.2 Heads of Departments should arrange for a simple visual check of

Departmental electrical equipment to be carried out frequently by all users. The connecting cable should be undamaged and securely fastened both at the appliance end and at the plug ends. The plug should be undamaged and not rattle, which could indicate loose terminals and potential danger. Any defects found must be rectified forthwith.

B.3.3 Heads of Departments should also arrange for more thorough maintenance

and testing at regular intervals of all electrical appliances in use within the Department. The arrangements must be set down in writing in the Departmental Safety Handbook and/or Laboratory Safety Manual as appropriate. The frequency of tests will depend on the amount and type of use, and Departments with a substantial inventory of equipment must determine their own programme based on their judgement of which equipment should be given priority and on the resources available.

B.3.4 It is recommended that Departments with suitably qualified personnel should

carry out the tests themselves using the schedule in Section B.7 as a guide. The University Engineer may be able to give further guidance to appropriate personnel from the Department and will also give advice on appropriate testing instruments for Departmental use.

B.3.5 For personnel within Departments carrying out testing of their electrical

equipment, the following guidelines apply:

(i) The person given the task of carrying out the checks must be competent to carry out the work and specifically, should have been instructed in the correct use of the instruments provided.

(ii) The results of all tests should be entered into a logbook (or on to a

loose sheet, which is subsequently filed in a central register in the Department). In addition, it is desirable to have a system of attaching a label to each item of equipment tested, identifying it, and the date of the most recent satisfactory test. Such records will provide evidence of compliance with the Regulations and with accepted safe working practice.

(iii) The information in the test record should include:

Description and identification of the piece of equipment being tested.

Nature of the test being carried out (as prescribed by the Department)

Date of test.

Name of tester.

Whether the test was satisfactory.

(iv) Note that in completing a record of this type, the tester is merely recording that he/she has carried out the test properly and in accordance with the prescribed method and that there was a given result (satisfactory or unsatisfactory). He/she is not certifying that the equipment is safe to use or will remain so, and hence bears no personal responsibility for any unsafe condition which may subsequently arise.

B.4 USE OF ELECTRICAL EQUIPMENT IN LABORATORIES AND

WORKSHOPS

B.4.1 There are special hazards in the use of electrical equipment in laboratories and workshops in that the equipment may be used in less than ideal conditions.

B.4.2 Particular problems arise when electrical equipment is used in the vicinity of

water or other conducting fluids. Care must be taken to ensure adequate segregation and protection to avoid fluids coming into contact with any electrical equipment.

B.4.3 When electricity is used for heating, for example in furnaces, problems may

arise due to deterioration of the supply cables near to heat sources and suitable high temperature insulated cables or thermal shielding must be provided.

B.4.4 In work places where flammable vapours may be present, care must be taken

to avoid electrical sparking leading to ignition. Where necessary, specially protected apparatus must be used. See Dangerous Substances and Explosive Atmospheres Regulations 2002 S1 2002/2776.

B.4.5 Supply cables should be properly protected from mechanical damage (cuts,

abrasions, etc.). It is good practice to arrange for each piece of apparatus to be connected to its own individual socket outlet with as short a lead as possible. The use of multi-way sockets, extension leads and trailing cables should be avoided.

B.4.6 Hand-held lamps or lamps used in connection with workshop machinery are

particularly vulnerable to damage and rapid wear. They should be adequately protected and in addition, should be fed from a low voltage (max. 25v) supply. (Other hazards may arise when equipment is being repaired or constructed and these are discussed in Part C).

B.5 BATTERIES

B.5.1 High current sources such as secondary batteries present special problems. Wherever possible they should be protected by fuses or circuit breakers as close as possible to the source.

B.5.2 Wherever possible batteries should be covered, so that short-circuits will not

be caused by objects falling across the terminals.

B.5.3 Rings must never be worn when working with unprotected high current sources. Even quite small nickel-cadmium cells have been known to produce enough current to sever a finger when short-circuited by a metal ring.

B.5.4 Rechargeable wet batteries must be used only in well-ventilated areas. During recharging an explosive mixture of hydrogen and oxygen is evolved which is easily ignited. Warning notices conforming to the appropriate British Standard should be displayed in all battery charging areas.

(Problems have arisen in testing the state of charge of batteries of this type. Use of a voltage drop method has been known to cause a spark leading to an explosion. The preferred method is to measure the specific gravity of the acid with a hydrometer).

B.5.5 When connecting and disconnecting batteries, great care should be taken to prevent arcing or sparking at the battery terminals by making and breaking the circuit away from the immediate vicinity of the battery.

B.6 CONNECTION OF ELECTRICAL EQUIPMENT TO HUMAN BEINGS

B.6.1 There are particular dangers in procedures where human beings are connected to electrical recording and/or stimulating apparatus.

B.6.2 There are not only those dangers which are inherent in the equipment itself

but those of unforeseen earth paths being created by the subject touching other electrical apparatus, sockets, conduits and other conductive material in the vicinity.

B.6.3 When humans are deliberately brought into contact with electricity, the

greatest care is needed to ensure that the equipment used and the systems of work adopted are of the highest standard and kept under constant review. This review should include a positive check on the relevant British Standards to ensure that developments in equipment safety and safe systems of work are progressively incorporated. Procedures must be fully documented and brought to the attention of all who need to know. All those involved in such procedures should be aware of the risks attached, particularly that of fatal electric shock, and of the action to be taken in emergency. If this is part of a study then ethical approval will be required.

B.6.4 There is comprehensive information on the categories and use of such

equipment in BS 5724 and this has been abstracted in J. Biomed. Eng. 1982 Vol. 4, July, pp 185-196.

B.7 ROUTINE CHECKS OF ELECTRICAL EQUIPMENT

Visual Checks:

B.7.1 there is no access to live parts;

B.7.2 there is no obvious mechanical damage to the equipment, cable or plug;

B.7.3 the cable grip is still gripping both the inner conductors and the outer protection of the cable;

B.7.4 any extra protective device around the cable where it enters the equipment is

undamaged and in position;

B.7.5 the cable does not pass through any openings with unprotected sharp edges;

Electrical Checks

B.7.6 the electrical connections between cable and plug are firmly and correctly made, and where applicable, a correctly rated fuse has been fitted;

B.7.7 the earth continuity is satisfactory;

B.7.8 insulation resistance is adequate;

B.7.9 earth leakage tests are satisfactory. (NOTE that special testing procedures are necessary on double-insulated [Class II] appliances marked with the symbol .

ALSO that special equipment is necessary for appliances with a capacitor across the mains input. Details of the standard tests are given in BS 2754 Construction of electrical equipment for protection against electrical shock and further advice may be obtained from the University Engineer.

B.8 MINIMUM MANUFACTURING STANDARDS

B.8.1 The following list of minimum manufacturing standards is based on British Standard specification BS EN 60335:2002 Safety of household and similar electrical appliances.

B.8.2 Before taking any electrical equipment into service (especially apparatus

constructed within the University), the Department should check that it complies with these requirements.

B.8.3 All accessible metal parts of electrical machines should be efficiently earthed.

B.8.4 All flexible cords, plugs, sockets and connectors should be of good quality

and standard. Flexible cables need to be adequately sized, constructed and protected, with proper connections and colour coding.

B.8.5 Mains input switches should be suitably placed on the machines, and the "On"

and "Off" positions properly identified and accessible.

B.8.6 All phases should be disconnected by the operation of the switch.

B.8.7 An effective over-current protection device (e.g. a fuse) should be provided in each phase of the circuit and arranged so as to disconnect the electricity supply to the equipment in the event of overload or short circuit.

B.8.8 If the supply to the equipment is made through an isolator, provision should

be made for securing the isolator switch against inadvertent and unauthorised operation, e.g. by use of padlocks. All live terminals should be effectively screened. Note particularly that if it is necessary for an operator to have access to particular parts of the interior of the machine, this should not allow access to live electrical parts at the same time.

B.8.9 If this is achieved by provision of guards with interlock switches, the switches

should be of such design and construction as to prohibit deliberate overriding or inadvertent operation, (see for example BS EN 60204-1:2006 Safety of machinery. Electrical equipment of machines. General requirements. provides requirements and recommendations) standard and frequency of maintenance and testing is all important in such circumstances.

B.8.10 All live conductors and terminals carrying dangerous voltages should be

securely screened and a suitable warning notice indicating the danger placed in a prominent position.

B.8.11 If heating elements are used in any equipment they should be placed and

installed so as to cause no deterioration of electrical equipment or overheating that would result in hazard to persons or plant.

B.8.12 If fluids, except for transformer oils and the like, are used in any equipment,

they should be used and housed so that they do not come into contact with electrical conductors and components. Where the incorporation of conducting of any other fluids into equipment is necessary, the design should, wherever possible, place such fluids at the lowest level possible. Any accidental release of fluids will, therefore, tend to cause the least danger. In the case of flammable fluids, special attention should be given to the machine enclosure to prevent dangerous concentration of vapour.

B.8.13 All electrical conductors and components should be housed or constructed so

as to avoid risk of fire or explosion, e.g. by the use of certified equipment or other equally effective measures.

B.8.14 Applicable Legislation

The Electrical Equipment (Safety) Regulations 1994 SI 1994/3260 Electromagnetic Compatibility Regulations 1992 SI 1992/2372

CODE OF PRACTICE FOR ELECTRICAL SAFETY PART C This part is designed for use in Departments where workers may need to have access to potentially hazardous voltages as a necessary part of their work and are specifically authorised to do so. Examples of situations in which this can occur are where fault diagnosis or repair are necessary, covers or panels are removed from electrical equipment and this results in access to hazardous voltages. A related situation is where an experimental rig is being built up and there is access to hazardous voltages at intermediate stages of construction. Relevant HSE guidance is included in: Guidance Note GS 38 - Electrical test equipment for use by electricians C.1 METHODS OF WORKING

C.1.1 The first priority is to protect all persons who are not associated with the equipment or test. The aim should be to prevent all such persons from having access to the dangerous voltages. This may be done by segregation, locking the work area to outsiders, by having an electrically-interlocked system so that access to the segregated area automatically disconnects the supply or, if any or all of these are not available, by prominent warning notices. The method(s) chosen will depend on an assessment of the likely hazard.

C.1.2 The next important point is to consider the methods of protection of the

operators. All operators should be trained to understand the hazards of the voltages involved and to be aware of the location of the hazardous regions in the particular equipment in use.

C.1.3 In assessing any situation for possible hazards, the knowledge and experience

of the operators should obviously be taken into account, but must not be relied on as the sole or main means of securing safe conditions. It must be borne in mind that even the most experienced operator may accidentally touch an exposed high voltage point because of a slip or fall or by being momentarily distracted. If the conditions are unfavourable such a momentary lapse could result in death or severe injury.

C.1.4 Layout of the working area is very important. If dangerous voltages are

necessarily exposed the apparatus or the bench on which it is supported should be surrounded by a clear and unobstructed zone and should be well clear of any adjacent benches or apparatus. This will minimise the risk of anyone inadvertently falling and touching a live conductor and of accidental contact between adjacent operators or equipment.

C.2 ENTRY TO PREMISES

C.2.1. Entry into any laboratory in which live conductors at voltages above 50 volts AC and 120 volts DC have to be exposed should be restricted to personnel who have been given specific permission in writing by the person in charge of the laboratory.

C.2.2 Under normal circumstances when dangerous voltages are necessarily

exposed, authorised persons should be in continuous attendance. In exceptional circumstances where a lengthy test necessitates a live system

being left unattended, the area should be protected by barriers to prevent unauthorised or inadvertent access. In any case, the laboratory should be locked, and keys available only to authorised persons.

C.3 EMERGENCY ARRANGEMENTS

C.3.1 Having carried out the systematic risk assessment advocated in Section C.1 (Methods of Work) a 'worst typical' situation should then be assumed, on which appropriate arrangements for use in an emergency can be based. Amongst other things, these will need to consider:

- Sources of assistance in case of electric shock and fire.

- Adequate means of raising the alarm.

- Access for and the safety of first aiders, firefighters, police, ambulance crews.

- Location of power cut-off devices (See Section C.6 Residual current devices).

- Location of insulating footwear, gloves, tools, etc.

- Evacuation routes.

C.3.2 Wherever possible, emergency stop buttons should be fitted so that all

electrical supplies (except for lighting) can be cut off in an emergency. These should be clearly marked. In areas with potentially high risks, persons should only work with another person within sight and sound. All persons should be aware of the emergency procedures and should be able quickly and safely to isolate the electrical supply, summon help and to start resuscitation treatment where necessary.

C.3.3 Instructions on the treatment of persons suffering from electric shock must be

prominently displayed in all places where voltages above 50 volts AC or 120 volts DC are in use.

C.4 REPAIRS

C.4.1 During repairs, protective covers may have to be removed thereby exposing live parts.

C.4.2 In these circumstances the hazard to be avoided is that of making a circuit

from the high voltage conductor to another conductor or to earth via the human body, with risk of fatal injury.

C.4.3 This type of work should not be carried out in remote areas away from other

workers who could give assistance in an emergency. (See C.3).

C.4.4 Electrical systems may involve a mains transformer, which reduces the voltages in the secondary to values less than 50 volts AC. In such a system the main risk will therefore be on the connections to the input to the primary.

Equipment should always be examined before use and further protection given to any exposed terminals in the circuit to minimise the risk. However, there will always be a residual risk.

C.4.5 The risks of a high voltage path to earth can be reduced by creating an earth-free area in which, as far as possible, all potential earth pathways are removed and an earth leakage protection device has been fitted or by using devices which will prevent the passage of earth fault current or limit the current to below 5mA. (See also Section C.6).

C.5 EARTH-FREE AREAS

C.5.1 Advice on the setting up of such areas is given in the HSE booklet IND(G) 354 – Safety in Electrical Testing at Work. The test bench, which should be constructed of insulating material, must be screened from metal-cased switches and plugs, conduit, radiators, heaters, window frames, water pipes and taps etc. Rubber mats to British Standard 921/1976 should be provided if the floor insulation cannot be relied on, and these must be kept in good repair and tested at intervals.

C.5.2 An isolating transformer complying with BS 61558 having an unearthed

secondary of 240 volts should be used as a "mains" supply inside the area, the transformer being situated outside the area.

C.5.3 Soldering irons and lamps be operated from a separate unearthed 24 volt

supply or be of the rechargeable battery type.

C.5.4 The area should preferably, be screened off by insulating barriers, and only one person at a time may be permitted in the earth-free area. No external signals should be brought into or transmitted from the area unless suitably isolated from normal mains and earth, e.g. by signal isolation amplifiers or signal isolation buffers, with an isolation of at least 1000v pk-to-pk.

C.6 RESIDUAL CURRENT DEVICES (RCDs) FOR EARTH LEAKAGE

PROTECTION

C.6.1 Residual current devices (previously ELCBs/RCCBs) monitor the current in the live and neutral conductors any imbalance will cause the device to trip.

C.6.2 RCDs can be installed in an electrical circuit as a protective device, which

will rapidly disconnect the mains supply if a fault current is detected. The magnitude of the fault current allowed is preset and in circumstances where shock to persons is anticipated this should be between 10mA and 30mA and trip the supply within 30mS. This limits the energy, which may be passed through the body. RCDs for protection against fire may have a preset sensitivity of up to 100mA. RCDs will not protect a person touching both live and neutral conductors.

C.6.3 The IEE Regulations state that all installations outside the equipotential zone,

i.e. external/outdoor from the main installation should be protected by RCDs. The Regulations make it clear, however, that reliance on this form of protection is not acceptable as the sole or main means of protecting persons from electric shock. RCDs may only be used as a useful backup to primary safeguards such as insulation, enclosure, low voltage etc.

C.7 REPAIRS IN THE FIELD

C.7.1 With bulky apparatus it may be necessary to undertake repairs on the spot away from specially equipped testing facilities. Under these circumstances,

operators must be especially aware of the potential risks and means of avoiding danger. Valuable protection can be given to persons carrying out electrical tests by providing them with a portable residual current device connected by a short cable to a multiple way socket block. All RCDs should be tested frequently by means of the inbuilt "test button" and also tested for current and time limits. When selecting RCDs care should be taken to ensure that they are suitable for use with equipment, which may produce a DC component on the supply, with the possibility of desensitising the RCD.

C.8 EXPERIMENTAL EQUIPMENT (See also B.2)

C.8.1 All rigs and temporary wiring should be constructed so as to conform fully to recognised electrical safety standards with regard to the strength and capability of conductors, insulation, connections, earthing, over-current protection, switching, isolation, access and all other aspects having a bearing on the safety of persons and equipment. "Temporary" is all too often used as an excuse for unsafe constructional standards and inadequate safety precautions.

C.8.2 Equipment should be constructed, wired and maintained to the standard

required for portable electrical equipment in general use. (See BS 2754).

C.8.3 Safety standards must not be relaxed because the equipment is undergoing development. The temptation to retain temporary arrangements once the experimental technique has been established must be firmly resisted. At that point every effort must be made to make the system as safe as possible. "Temporary" arrangements may by default last for long periods, sometimes after the constructor has left the University, and this results in potential danger to future users. Similarly, a comprehensive circuit diagram should always be made available and kept with the equipment. Details of modifications to standard equipment should also be fully documented.

C.8.4 Protection against electric shock should be incorporated as soon as possible.

Prior to that stage, appropriate warning notices should be displayed giving information and warning of temporary hazards.

C.8.5 It is strongly recommended that control gear associated with 415v 3-phase

equipment should be operated at 110v AC from a 55-0-55v supply with an earthed centre point.

C.9 ADDITIONAL REQUIREMENTS FOR DISTRIBUTION TO RESEARCH OR

EXPERIMENTAL APPARATUS SUPPLIED AT, OR GENERATING, VOLTAGES ABOVE 650 VOLTS AC AND DC

C.9.1 All apparatus on which conductors may be exposed when live at a voltage

above 650 should be placed in a segregated enclosure so as to prevent danger. C.9.2 Arrangements should be such that the enclosure cannot be entered unless the

supply has been made dead and earthed either by the use of a door operated limit switch supplemented by a door operated gravity earth or by the interlocking of the door with a supply circuit breaker using figured key interlocks. Additionally, a portable earthing rod should be provided within the enclosure, and applied to exposed conductors before contact with them is made. This restriction does not normally apply to non-lethal high voltage systems where the current availability is below 5mA.

APPENDIX 1 HSE and HSC publications on electrical safety Guidance Note

Title

Regulations particularly relevant

PM 29 Electrical hazards from steam/water pressure cleaners

ISBN 0 7176 0813 1

4, 6, 7, 8, 10

PM 38 Selection and use of electric handlamps ISBN 0 11 886360 6

4, 6, 7, 8, 10, 12

GS 6 Avoidance of danger from overhead electric lines ISBN 0 7176 1348 8

4, 14, 15, 16

GS 38 Electrical test equipment for use by electricians ISBN 0 7176 0845 X

10, 14, 16

GS 50 Electrical safety at places of entertainment ISBN 0 7176 1387 9

4, 5, 6, 7, 8, 10, 11, 12

HSG 38 Lighting at work: ISBN 0 7176 1232 5

4, 13, 14, 15

HSG 47 Avoiding danger from underground services

ISBN 0 7176 1744 0

4, 14, 16

HSG 85 Electricity at work - safe working practices ISBN 0 7176 2164 2

4, 7, 12, 13, 14, 15, 16

HSG 118 Electrical safety in arc welding

ISBN 0 7176 0704 6 4, 6, 7, 8, 10, 12, 14, 16

HSG 141 Electrical safety on construction sites ISBN 0 7176 1000 4

4 - 16 inclusive

HSG 230

Keeping electrical switchgear safe ISBN 0 7176 2359 9

4, 5, 6, 11, 12

INDG 231

Electrical safety and you ISBN 0 7176 1207 4

4 - 16 inclusive

INDG 236

Maintaining portable electrical equipment in offices ISBN 0 7176 1272 4

NOTE: The publications listed in Appendix 1 are available from HSE Books

APPENDIX 2

Other publications having an electrical safety content Standards, Codes of Practice and other publications, which contain guidance relevant to the Regulations and electrical safety, which have been published by bodies other than either HSE or HSC, are given in this appendix. Most of these documents are the product of technical committees on which HSE has been represented. This does not mean, however, that the documents are concerned solely with safety and users should bear in mind the scope of the safety content of these documents and the fact that they have largely been arrived at through a process of consensus. Note: British Standards Institution publications are obtainable from BSI Sales and Customer Services, 389 Chiswick High Road, London W4 4AL. Tel: 0181 996 7000. Fax: 0181 996 7001. Title of Publication

Principal regulations relevant

Comments

(BS = British Standard)

International Electrotechnical Commission Publication 479. Effects of current passing through the human body. Parts I and II. Also published as BS PD 6519 Pts 1 and 2.

2 Definition of 'danger' and 'injury' - electric shock

International Electrotechnical Commission Guide 105. Principles concerning the safety of equipment electrically connected to a telecommunications network.

2 Ditto - on telecommuncation systems

IEC 1201:1992 Extra-low Voltage (ELV) limit values. Also published as BS PD 6536:1992

2 Electric shock - sets out limit values

BS 7671: 2001 Requirements for Electrical Installations (IEE Wiring Regulations Sixteenth edition) (obtainable from the IEE, PO Box 96, Stevenage, Herts, SG1 2SD).

4(1 5-12 inclusive

Selection of equipment and construction of installations up to 1000 volts AC.

BS 4363:1968. Specification for distribution units for electricity supplies for construction and building sites.

4, 6, 10

BS 7375:1991 Distribution of electricity on construction and building sites.

4, 6, 10

BS 5486 Pt 1:1990 (up to 1000 V ac and 1200 V dc) BS 5227:1984 (above 1000 V ac and 1200 V dc).

4, 5, 12, 15 Particular attention for switchgear clearance distances. Safety clearances and work sections.

BS 6423:1983 Code of practice for

4(2), 4(3),

Precautions to secure safety of

maintenance of electrical switchgear and control gear for voltages up to and including 650 V.

12, 13 maintenance, personnel isolation procedures

BS 6626:1985 Code of practice for maintenance of electrical switchgear and control gear for voltages above 650 V and up to and including 36 kV.

4(2), 4(3), 12, 13

Precautions to secure safety of personnel

BS 6867:1987 Code of practice for maintenance of electrical switchgear and control gear for voltages above 36 kV.

4(2), 4(3), 12, 13

Precautions to secure safety of personnel

BS EN 60204-1:1993 Electrical equipment of machines. Specification for general requirements.

4, 6

BS 697:1986 Specification for rubber gloves for electrical purposes.

4(4), 14

BS 921:1976 (1987) Specification. Rubber mats for electrical purposes.

4(4), 14 Mats for covering floor near electrical equipment where direct contact may occur

BS 5490:1977 (1985) Specification for classification of degrees of protection provided by enclosures.

6, 7 Index of protection (IP) system against contact with live and moving parts and ingress of solids and moisture and finger test

BS 5420:1977 Specification for degrees of protection of enclosures of switchgear and control gear for voltages up to and including 1000 V ac and 1200 V dc.

6, 7 Index of protection (IP) system against contact with live and moving parts and ingress of solids and moisture and finger test

BS 4999 Part 20:1972 General requirements for rotating electrical machines. Classification of types of enclosure.

6, 7 Index of Protection (IP) system against contact with live and moving parts and ingress of solids and moisture

BS 5345 Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosive processing and manufacture).

4(1), 4(2), 6 See also HSE booklet HSG22 (Appendix 1)

BS 5501 Electrical apparatus for potentially explosive atmospheres.

4(1), 6 See also HSE booklet HSG22 (Appendix 1)

BS CP 1003 Electrical apparatus and associated equipment for use in explosive atmospheres of gas or vapour other than mining applications (obsolescent, replaced by Parts 1 to 8 of BS 5345 but retained as a reference guide).

4(1), 4(2), 6 See also HSE booklet HSG22 (Appendix 1)

BS 6742 Part 1:1987 Electrostatic painting and finishing equipment using flammable materials specification for hand-held spray guns and associated apparatus.

6 Protection against ignition

BS 6467:Part 1:1985 Electrical apparatus with protection by enclosure for use in the presence of combustible dusts. Specification for apparatus.

6 Protection against ignition

BS 6467:Part 2:1988 Guide to selection, installation and maintenance.

4, 5, 6 Protection against ignition

BS 6651:1992 Code of practice for protection of structures against lightning.

6 As relevant to protection of electrical equipment from lightning.

BS 5958:1991 Code of practice for control of undesirable static electricity.

6 Precautions against ignition and electric shock

BS 4444:1969 (1980) Guide to electrical earth monitoring.

8

BS 7430:1991 Earthing

8

BS 5419:1977 (1990) Specification for air break switches, air break disconnectors and fuse-combination units for voltages up to and including 1000 V ac and 1200 V dc.

12

BS 2754:1976 Memorandum Construction of electrical equipment for protection against electric shock.

7, 8

BS 5655:Part 1:1986 Safety rules for the construction and installation of electric lifts.

15 Clear areas in front of electric equipment specified (Clause 6.3.2.1)

BS 5253:1990 Specification for AC disconnectors and earthing switches. To be read in conjunction with BS 6581:1985

12

Code of Practice for In-Service Inspection and Testing of Electrical Equipment ISBN 0 85296 776 4

BS EN 60204-1:2006 Safety of machinery. Electrical equipment of machines. General requirements

APPENDIX 3 Working space and access; historical comment on revoked legislation (see regulation 15) Among the legal provisions revoked upon the coming into force of the Electricity at Work Regulations 1989 were the Electricity (Factories Act) Special Regulations 1908 and 1944. Regulation 17 of those Regulations specified minimum width and height dimensions of 'switchboard passage-ways' if there were 'bare conductors' exposed or arranged to be exposed when 'live' so that they may be touched. These related to what are commonly known as 'open type' switchboards, which had much exposed copper work, knife switches etc. That regulation (and the key definitions used at that time) is reproduced below for information. The dimensions, which were specified by that regulation were arrived at after much consideration of the circumstances at the time. A compromise was struck between the objective of achieving the safety of those who had to work at and operate these 'open type' switchboards and the need to recognise the constraints imposed by the installations existing and the nature of the technology in 1908. Even though the dimensions were a compromise it was widely recognised that they were a good minimum standard which had been found necessary following a number of severe and fatal accidents in factories and power stations due to inadequate space or cluttered access in the vicinity of bare live conductors at these 'open type' switchboards. The dimensions chosen allowed workmen to operate or otherwise work upon the switchboard in reasonable safety and allowed, for example, persons to pass one another in the switchboard passageway without being placed at unacceptable risk of touching live conductors. Where the need does arise to work on or near live conductors, the principles of providing adequate working space and uncluttered access/egress, which were expressed in regulation 17 of the Electricity (Factories Act) Special Regulations 1908 and 1944, should be given proper consideration. Regulation 17 (of 1908 Regulations) At the working platform of every switchboard and in every switchboard passageway, if there be bare conductors exposed or arranged to be exposed when live so that they may be touched, there shall be a clear and unobstructed passage of ample width and height, with a firm and even floor. Adequate means of access, free from danger, shall be provided for every switchboard passageway. The following provisions shall apply to all such switchboard working platforms and passage-ways constructed after January 1, 1909 unless the bare conductors, whether overhead or at the sides of the passageways, are otherwise adequately protected against danger by divisions or screens or other suitable means: (a) Those constructed for low pressure and medium pressure switchboards shall have a clear

height of not less than 7 ft and a clear width measured from bare conductor of not less than 3 ft.

(b) Those constructed for high pressure and extra high pressure switchboards, other than

operating desks or panels working solely at low pressure, shall have a clear height of not less than 8 ft and a clear width measured from bare conductor of not less than 3 ft 6 in.

(c) Bare conductors shall not be exposed on both sides of the switchboard passageway unless

either (i) the clear width of the passage is in the case of low pressure and medium pressure not less than 4 ft 6 in and in the case of high pressure and extra high pressure not less than 8 ft in each case measured between bare conductors, or (ii) the conductors on one side are so guarded that they cannot be accidentally touched.

Key definitions used in the 1908 regulations Switchboard means the collection of switches or fuses, conductors, and other apparatus in connection therewith, used for the purpose of controlling the current or pressure in any system or part of a system. Switchboard passageway means any passage-way or compartment large enough for a person to enter, and used in connection with a switchboard when live. Low pressure means a pressure in a system normally not exceeding 250 volts where the electrical energy is used. Medium pressure means a pressure in a system normally above 250 volts, but not exceeding 650 volts, where the electrical energy is used. High pressure means a pressure in a system normally above 650 volts, but not exceeding 3000 volts, where the electrical energy is used or supplied. Extra-high pressure means a pressure in a system normally exceeding 3000 volts where the electrical energy is used or supplied.

APPENDIX 4

UNIVERSITY OF LEICESTER

CODE OF PRACTICE FOR ELECTRICAL SAFETY

GUIDE TO THE ELECTRICITY AT WORK REGULATIONS 1989 (SI 1989 NO. 635)

INTRODUCTION 1. As the Foreword to the Code of Practice points out, the statutory requirements

relating to electricity at work are contained in the Regulations. The best currently available source of information on the Regulations and their interpretation is contained in a publication from the Health and Safety Executive under the title:

Memorandum of Guidance on the Electricity at Work Regulations HS(R)25 ISBN 0717616029 (HMSO £4.00 net).

2. Copies are readily available from the University's Bookshop and Departments having

a substantial inventory of electrical equipment and/or who will be involved in routine electrical testing as required by the University Code of Practice are strongly advised to obtain a copy. The publication will be particularly important and useful to those Departments affected by Parts B and C of the Code (See Introduction, Section 1.3 p3).

3. As a means of ready reference, however, this Appendix summarises the text of each

Regulation with a brief note on its implications, cross-referenced to the relevant Section(s) of the University Code.

ELECTRICITY AT WORK REGULATIONS 1989 Regulation 1 (Citation and commencement) is procedural only. Regulation 2 Gives important interpretations of terms used in the various sections. 'Injury' for example, is defined as death or injury to persons from: (a) electric shock; (b) burns caused by electricity; (c) fires having an electrical cause; (d) electric arcing; (e) explosions initiated or caused by electricity. 'Danger' is defined as the risk of injury. Comment: These terms occur frequently throughout the Regulations. It is therefore

important to know what it is that the Regulations are designed to do, as well as to be aware of their limitations. Some of the Regulations, for example, are qualified by the phrase 'so far as is reasonably practicable', which means that the 'danger' as defined has to be balanced against the time, trouble, inconvenience and funds that would be needed to obviate or substantially reduce such danger. This qualification applies to Regulations:

4(1) Construction of electrical systems. 4(2) Maintenance (including testing) of systems. 4(3) Conduct or work activities on electrical systems. 6. Electrical systems in adverse conditions (mechanical damage, weather, wet,

flammable or explosive environments etc.) 7. Insulation, protection and placing of conductors.

A Regulation, which is qualified by the phrase 'so far as is reasonably practicable' is not elective, nor is it weakened in any way by the qualification. Indeed, in many instances the duty is more difficult to comply with since the risk assessment referred to above must show clearly that the time, trouble, inconvenience and funds needed to obviate or substantially reduce the danger are wholly excessive and out of balance and that therefore it is not 'reasonably practicable' to follow or not a particular course of action. The process of deciding whether or not a course of action is 'reasonably practicable' can be likened to putting danger on one side of a scale and the time, trouble, inconvenience and funds on the other. Where one side or the other is obviously outweighed, the correct course of action is clear. When the 'scales' are in balance, or when one side only marginally outweighs the other, the right decision becomes less clear, requiring much more careful thought. In such cases, it becomes more important that the risk assessment process should be fully documented as a defence in the event of prosecution. (See below). The rest of the Regulations are 'absolute' in nature and cannot be qualified. An absolute requirement must be met regardless of cost or inconvenience. Those having authority and responsibility under the Regulations ('duty holders' as they are termed) can, however, offer the defence that they 'took all reasonable steps' and 'exercised all due diligence' to avoid committing an offence.

Such a situation would only arise in the course of prosecutions, and whether the defence succeeded or not would depend on the decision of the Court in the light of evidence presented. Regulation 3 Refers to duties and to persons on whom duties are placed by the Regulations. Comment: The greater part of the statutory duties rest on the employer. However,

employees also have duties; to co-operate with the employer for example, in maintaining safe systems of work and - very importantly - to comply with the Regulations insofar as such compliance lies within their control. This latter recognises the authority conferred by technical knowledge, skill and expertise and the consequent responsibility which must be accepted by skilled employees for their own and others safety in respect of electrical work.

(See also Regulation 16 on 'competence').

Regulation 4 4(1) requires that all electrical systems shall be of such construction as to prevent danger

so far as is reasonably practicable; 4(2) requires that all systems shall be maintained so as to prevent danger so far as is

reasonably practicable (University Code B.3, B.7); 4(3) requires that operation, use and maintenance of an electrical system shall not so far as

is reasonably practicable give rise to danger (University Code B.2); 4(4) states that 'any equipment provided under these Regulations for the purpose of

protecting persons at work on or near electrical equipment shall be suitable for the purpose for which it is provided, be maintained in a condition suitable for that use and be properly used'.

Comment: 'Protective equipment' is a wide-ranging term which includes the special tools,

clothing, boots, gloves, screens, mats, benches etc. that may be necessary to enable electrical work to be carried on with safety. Note that this, like most of the Regulations, is absolute in recognition of the 'last-ditch' nature of, for example, insulating gloves and mats. It is also worth noting the requirement that, when such equipment is provided, it must be properly used by employees.

Regulation 5 Requires that electrical equipment shall not be put into use in ways or under conditions in which its 'strength and capability' might be exceeded in such a way as to give rise to danger. Comment: The term 'strength and capability' refers to the ability of the equipment to

withstand the effects of electrical current which might be expected to flow through it when the equipment is part of a system. Those currents include, for example, load currents, transient overloads, fault currents, pulses of current and, for alternating current systems, currents at various power factors and frequencies. Insulation must be effective to enable the equipment to withstand the applied voltages and any likely over-voltages.

It is recommended that the equipment is used within the manufacturer's rating (continuous, intermittent or fault rating as appropriate) and in accordance with any accompanying instructions, operating manuals or accepted practice for such equipment.

Regulation 6 States that 'electrical equipment which may reasonably foreseeably be exposed to: (a) mechanical damage; (b) the effects of the weather, natural hazards, temperature or pressure; (c) the effects of explosive substances, including dusts, vapours or gases, shall be of such

construction or as necessary protected as to prevent, so far as is reasonably practicable, danger arising from such exposure'.

Comment: The implications of the Regulation are of particular interest to Universities,

where many of the conditions envisaged may be encountered. 'Mechanical damage' for example, could refer to the vacuum cleaner pulled along by its supply cable. 'Effects of the weather' is relevant to the outdoor use of power tools. 'Explosive substances....vapours or gases' can be found in many distillation/reduction processes.

Where such conditions are anticipated, the equipment must be constructed accordingly by means of extra robustness, spark/flameproofing, isolation from the source of danger or whatever is appropriate in the circumstances. (University Code B.1, B.2, B.3, B.4).

Regulation 7 Refers to the 'insulation, protection and placing of conductors'. 7(a) States that 'all conductors in a system which may give rise to danger shall be suitably

covered with insulating material and as necessary protected so as to prevent, so far as is reasonably practicable, danger'.

Comment: 'Suitably covered' means insulated in ways that are appropriate to the kind of

service the conductors are required to undertake. Temporary insulation, for example in situations where adequate insulation is critical, would be a breach of the Regulation, as would routing an insulated conductor over a hot surface or a sharp edge. (University Code B.2, B.4, B.7).

Regulation 8 Requires precautions to be taken 'either by earthing or by other suitable means, to prevent danger arising when any conductor (other than a circuit conductor) which may reasonably foreseeably become charged as the result of either the use of a system or a fault in a system, becomes so charged and, for the purposes of ensuring compliance with this Regulation, a conductor shall be regarded as earthed when it is connected to the general mass of earth by conductors of strength and current-carrying capability to discharge electrical energy to earth'. Comment: The length and wording of this Regulation reflect the central importance of

the subject to electrical safety. The HSE's Memorandum has close on three A4 pages of detailed guidance on earthing and equivalent precautions, which will repay close study. (University Code B.3, B.4, B.6, B.8, C.4, C.5, C.7, C.8, C.9).

Regulation 9 (Integrity of referenced conductors). The Regulation reads: 'If a circuit conductor is connected to earth or to any other reference point, nothing which might reasonably be expected to give rise to danger by breaking the electrical continuity or introducing high impedance shall be placed in that conductor unless suitable precautions are taken to prevent the danger'. Comment: The object of the Regulation is to prevent referenced circuit conductors which

should be at or about the same potential as the reference point from reaching significantly different potentials thereby giving rise to possible danger. (There is the need, for example, in 3-phase systems, where the neutral conductor is connected to earth at the source of supply, to ensure that the phase voltages match and are not affected by discrepancies in loading). (University Code B.2, B.8, C.5, C.8, C.9).

Regulation 10 Refers to electrical connections and states: 'Where necessary to prevent danger, every joint and connection in a system shall be mechanically and electrically suitable for use.' Comment: The Regulation requires that all connections in a circuit and protective

conductors (including connections to terminals, plugs and sockets and any other means of joining or connecting conductors) must be suitable for the intended duty. It is true to say that, of the thousands who daily attach 3-pin 13-amp plugs to equipment and appliances, only a minority understand the electrical principles lying behind this apparently simple task. One of the most frequent causes of electrical fatalities is the malfunctioning of dangerously connected plugs, with over-stripping, cross connection, and failure to securely clamp circuit and protective conductors the most common faults.

Special attention should be given to joints and connections in cables and equipment, which will be handled, for example, flexible cables for portable equipment. Specific guidance is given in Appendices 1 and 2 and in the University Code (A.2, A.3, B.2, B.3, B.4, B.6, B.7.3, B.8.10, C.8).

Regulation 11 Refers to the 'means for protecting from excess of current'. HSE guidance deals at length with the various techniques for preventing danger and damage from over-current conditions. Topics include: (a) The need to anticipate abnormal conditions. (b) Selection of excess current protective devices. (c) The nature of the circuits and type of equipment to be protected. (d) The short circuit energy available in the supply (the fault level). (e) The nature of the environment. (f) Whether the system is earthed or not. It is recognised that in conditions where excess current is drawn due to a fault or overload, (e.g. an arcing fault), it may be technically impossible to achieve e total compliance with the 'absolute' requirements. The defence of 'all due diligence/all practicable steps' is available in such circumstances and the HSE's Memorandum gives examples of how this might be demonstrated. (University Code A.1, A.3, B.2, B.5, B.7, B.8, C.8).

Regulation 12 States: (1) Subject to paragraph (3), where necessary to prevent danger, suitable means

(including, where appropriate, methods of identifying circuits) shall be available for -

(a) cutting off the supply of electrical energy to any electrical equipment; and

(b) the isolation of any electrical equipment. (2) In paragraph (1) 'isolation' means the disconnection and separation of the electrical

equipment from every source of electrical energy in such a way that this disconnection and separation is secure.

(3) Paragraph (1) shall not apply to electrical equipment which is itself a source of

electrical energy but, in such case as is necessary, precautions should be taken to prevent, so far as is reasonably practicable, danger.

The HSE Memorandum amplifies the important distinction between 'switching off' and 'isolation'. Regulation 12(1)(a) 2 The objective is to ensure that, where necessary to prevent danger, suitable means are available by which the electricity supply to any piece of equipment can be switched off. Switching can be for example by direct manual operation or by indirect operation via 'stop' buttons in the control circuit of contactors or circuit breakers. Regulation 12(1)(b) 3 Whereas regulation 12(1)(a) requires means to be provided whereby the supply of electrical energy can be switched off, 12(1)(b) requires that there will be available suitable means of ensuring that the supply will remain switched off and inadvertent reconnection prevented. This is isolation. This provision, in conjunction with safe working practices, will enable work to be carried out on electrical equipment without risk of it becoming live during the course of that work, for example if the work is to be done under the terms of Regulation 13. 4 In some cases the equipment used to comply with Regulation 12(1)(a) may also be used to secure compliance under 12(1)(b). It must be understood that the two functions of switching off and isolation are not the same, even though in some circumstances they are performed by the same action or by the same equipment. (University Code B.2, B.8, C.1, 2, 3, 4, 5, 6, 7, 8, 9). Regulation 13 States: 'Adequate precautions shall be taken to prevent electrical equipment, which has been made dead in order to prevent danger while work is carried out on or near that equipment, from becoming electrically charged during that work if danger may thereby arise.' Comment: This is an extremely important regulation. (There are depressingly regular

reports of fatalities due to 'dead' equipment being inadvertently made live by someone switching the power on elsewhere).

Further explanation from the Memorandum is as follows:

'The precautions should be effective in preventing the electrical equipment from becoming charged in any way which would give rise to danger.

In the first place the procedures for making the equipment dead will probably involve use of the means required by Regulation 12(1)(a) for cutting off the supply of electrical energy. Isolation of the electrical equipment will be necessary and the means required by Regulation 12(1)(b) will facilitate this. Ideally a means of locking off an isolator can be used. Where such facilities are not available, the removal of fuses or links and their being held in safekeeping can provide a secure arrangement if proper control procedures are used.'

The guidance warns that these precautions may not be sufficient, for example where stored electrical energy is present. It may be necessary to apply earthing connections at appropriate points. Before working on a 'dead' system the conductors should first be proved dead.

Formal written instructions, including permit-to-work arrangements should be used for high voltages or very complex systems. (University Code B.2, B.6, B.8, C.1, C.8, C.9).

Regulation 14 Refers to working on or near live conductors. The HSE's Memorandum gives a wealth of detailed advice on the hazards posed by 'live working' and the precautions to be taken where this is unavoidable. Regulation 15 States: 'For the purposes of enabling injury to be prevented, adequate working space, adequate means of access and adequate lighting shall be provided at all electrical equipment on which or near which working is being done in circumstances which may give rise to danger'.

Comment: This applies to any work, which may give rise to danger, not only live working.

Guidance in the HSE's Memorandum includes the following:

'2 The purpose of the regulation is to ensure that sufficient space, access and adequate illumination are provided while persons are working on, at or near electrical equipment in order that they may work safely. The requirement is not restricted to those circumstances where live conductors are exposed but applies where any work is being done in circumstances, which may give rise to danger. The regulation makes no requirement for such space, access or illumination to be provided at times other than when work is being done. (But see guidance under Regulation 12(1)(a), in respect of safe access to means of cutting off the supply).

5 Natural light is preferable to artificial light but where artificial light is necessary it is preferable that this be from a permanent and properly designed installation, for example in indoor switch rooms etc. However, there will always be exceptions and special circumstances where these principles cannot be achieved, where hand-lamps or torches will be the sole or most important means of lighting. Whatever level of lighting is used it must be adequate to enable injury to be prevented.'

The guidance on working space is reproduced as Appendix 3 to the University Code. (The whole of Part C of the Code may also be relevant depending on the circumstances).

Regulation 16 (Competence of persons carrying out work with electricity) The Regulation states: 'No person shall be engaged in any work where technical knowledge or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may be appropriate having regard to the nature of the work.' The HSE Memorandum makes it clear that the object of this Regulation is that persons are not placed at risk due to a lack of skill on the part of themselves or others in dealing with electrical equipment. University Departments engaged in such work should review their staffing arrangements in the light of the advice given, with the aim of ensuring an appropriate matching of competence and assigned work activities. Other important interpretations are: '...prevent danger or, where appropriate, injury...' 3 This regulation uses both of the terms 'injury' and 'danger'. The regulation therefore applies to the whole range of work associated with electrical equipment where danger may arise and whether or not danger (or the risk of injury) is actually present during the work. It will include situations where the elimination of the risk of injury, i.e. the prevention of danger, for the duration of the work is under the control of a person who must therefore possess sufficient technical knowledge or experience, or be so supervised, etc. as to be capable of ensuring that danger is prevented. For example where a person is to effect the isolation of some electrical equipment before this person undertakes some work on the equipment, they will require sufficient technical knowledge or experience to prevent danger during the isolation. There will be no danger from the equipment during the work provided that the isolation has been carried out properly. Danger will have been prevented but the person doing the work must have sufficient technical knowledge or experience so as to prevent danger during that work, for example by knowing not to work on adjacent 'live' circuits. 4 But the regulation also covers those circumstances where danger is present, i.e. where there is a risk of injury, as for example where work is being done on live or charged equipment using special techniques and under the terms of Regulation 14. In these circumstances persons must possess sufficient technical knowledge or experience or be so supervised etc. as to be capable of ensuring that injury is prevented. Technical knowledge or experience 5 The scope of 'technical knowledge or experience' may include: (a) adequate knowledge of electricity; (b) adequate experience of electrical work; (c) adequate understanding of the system to be worked on and practical experience of

that class of system; (d) understanding of the hazards which may arise during the work and the precautions

which need to be taken; (e) ability to recognise at all times whether it is safe for work to continue.

Allocation of responsibilities 6 Employees should be trained and instructed to ensure that they understand the safety procedures which are relevant to their work and should work in accordance with any instructions or rules directed at ensuring safety which have been laid down by their employer. Supervision 7 The regulation recognises that in many circumstances persons will require to be supervised to some degree where their technical knowledge or experience is not of itself sufficient to ensure that they can otherwise undertake the work safely. The responsibilities of those undertaking the supervision should be clearly stated to them by those duty holders who allocate the responsibilities for supervision and consideration should be given to stating these responsibilities in writing. Where the risks involved are low, verbal instructions are likely to be adequate but as the risk or complexity increases, there comes a point where the need for written procedures becomes important in order that instructions may be understood and supervised more rigorously. In this context, supervision does not necessarily require continual attendance at the work site, but the degree of supervision and the manner in which it is exercised is for the duty holders to arrange to ensure that danger, or as the case may be, injury is prevented. Further advice on working procedures is given in guidance publications listed in Appendix 1. (University Code: Introduction 1.2). Regulations 17 to 28 apply to Mines and are not dealt with either in the HSE's Memorandum or in the University's Code of Practice. Regulation 29 Defence (in criminal proceedings). Reference is made throughout the HSE's Memorandum to the 'defence', which is available in any proceedings for an offence under these Regulations. Some misinterpretations suggest that if compliance with a Regulation is costly or inconvenient it can be ignored. Others, even more misguided and dangerous, suggest that the Regulations apply only to industrial and similar activities and that Universities are partly or even wholly exempt. Such assumptions are wholly incorrect and liable to bring individuals holding such views, and their institutions, into conflict with the law, as the relevant text below makes clear: 'In any proceedings for an offence consisting of a contravention of Regulations 4(4), 5, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 25, it shall be a defence for any person to prove that he took all reasonable steps and exercised all due diligence to avoid the commission of that offence. Regulation 29 applies only in criminal proceedings. It provides a defence for a duty holder who can establish that he took all reasonable steps and exercised all due diligence to avoid committing an offence under Regulations 4(4), 5, 8, 9, 10, 11, 12, 13, 14, 15 or 16. (Regulation 25 applies only to mines)'. Regulations 30-33 These are procedural and administrative only and are omitted.