ELECTRICALSAFETY ON

CONSTRUCTIONSITES

HSE BOOKS

The risk

10 Each year, people are killed or seriously injuredby electricity in the construction industry. Most of theseaccidents could be avoided.

11 Construction sites present one of the mostchallenging environments to the safe use of electricity.Much of the work is done outdoors in all weathers -damp and wet conditions increase the risk andpotential severity of shock. Sites are constantlychanging as the work progresses, so there is always atemptation to improvise supply systems. Excavations,demolition work and routine construction activities mayall result in damage to both the temporary sitedistribution system and/or the existing fixed installation.

12 Cables and equipment are likely to be damagedby the movement of heavy plant and materials. Duringinstallation work sites are often congested, whichmakes the control of risk more difficult. There may alsobe confusion as to which parts of the temporary,existing or new installations are live, and which havebeen made dead.

13 The temporary site distribution system may beused by a wide range of people who often work fordifferent contractors and who will have various needsand expectations. Contractors may provide their owntools and equipment, or use equipment provided byothers. Effective management is necessary to ensurethat all the equipment is smaintained.

suitable for use atid is properly

C O N T E N T SIntroduction

LegislationThe risk

Planning the workAdvice from the electricity supplierOverhead lines and underground cablesThe supply voltageSelection of equipment for the temporary site distribution systemStaff appointments

The safety of the electrical installationGeneratorsEarthing the site supplyEarthing equipment connected to the supplyThe temporary site distribution systemMoveable plantPortable equipment

’ Use of mains voltage equipmentResidual current devices (RCDs)Maintaining the electrical installationMaintaining portable electrical equipment

Table: Suggested inspection and test frequencies forelectrical equipment on a construction site

Demolition Page 28

Building alteration and refurbishment Page 28

Handover and commissioning work Page 29

Safe working practices

Treatment of electric shock victims

Appendices1 Legislation2 Technical notes on residual current devices and

reduced low voltage systems3 Emergency procedures for an electric shock casualty

Page 124

Page 5899

I212

Page 1414151717192021222324

Page 27

Page 30

Page 30

Page 3232

3437

References and further reading Page 41

I combat the risks at source, if risks cannot beeliminated, eg by programming and controllingthe work to ensure that parts of a new permanentelectrical system are not commissioned until allwork on the installation has been completed;

I give priority to risk control measures that willprotect all workers.

18 Depending on the type of project, the design andplanning decisions will be made at different stages.Some decisions may be made by architects (eg, thelocation of the structure in relation to overhead lines),some will be made or influenced by specialistequipment suppliers (who may also be designers), andother decisions might only be finalised when detailedplanning is done by the main or principal contractor. It istherefore important for those planning the work to makesure that there is co-operation between the variousparties. This will achieve a co-ordinated andcomprehensive approach to the control of electrical risk.Depending on the stage of the project, this duty may fallto either the person planning the work, or the maincontractor (planning supervisor or principal contractoron sites where the CDM Regulations apply).

19 At the design and planning stage, and as theproject develops, issues which will need to beconsidered or reviewed will include the following:

m

m

m

m

m

the need to alert the electricity supplier to thenature, duration and likely start date for the work;

the location of overhead lines and buried cables;

environmental considerations, eg the season inwhich the work is to take place (often wet inwinter), ground conditions such as waterlogging,(which increases the risk of serious injury fromelectric shock);

the supply voltages to be used for offices, plant,equipment etc;

the need to use generators to provide all or part ofthe site supply;

1 Electricity can kill. Every year, the use ofelectricity on construction sites results in a number ofaccidents. People suffer electric shocks and burnswhich can in themselves cause serious and sometimesfatal injury. People may also fall from ladders, scaffoldsand other equipment as a consequence of the shock,which can result in further injury. Also, those using theelectricity may not be the only ones at risk, for examplefaulty equipment may lead to a scaffold becoming liveor short circuits can result in fires.

2 This guidance book gives advice on precautionsthat can be taken to reduce the risk of accidents duringthe construction phase. It covers the:

m installation and use of the temporary sitedistribution system (designed to distribute andsupply electricity to plant, work equipment, sitei ;offices and site huts etc); Contact with underground

cab/es can k//l

Location of metering

equipment point of supply

information which the principal contractor is likely toneed to manage those risks. The principal contractorshould then develop a plan which sets out how theserisks will be managed and controlled during theconstruction phase. This should include any unusualrisks or risks requiring particular attention.

21 Contractors coming to site should be providedwith information about relevant risks. The principalcontractor may make site rules (eg, specifyingacceptable types of equipment; the maximum voltagefor portable tools which may be used on site; workingprocedures; commissioning procedures). Contractorsshould co-operate with the principal contractor toensure that any rules or agreed methods of working areput into practice.

Advice from the electricity supplier

22 Early contact with the electricity supplier isstrongly recommended. While this is normally carriedout during the planning stage, discussions between theelectrical system designers, or the contractors who willcarry out the work and the electricity supplier are alsorecommended. Many of the issues raised in paragraph19 will be relevant to these discussions, in particularthe:

correct rating of fuses and switchgear at the pointof supply;

use of generators in addition to the public supply(see paragraph 44);

earthing requirements or earthing systems to beused;

likely use of very heavy plant (eg, tower cranes)needing a high voltage supply (close liaison withthe electricity supplier is essential and specialistadvice may be necessary);

location of metering equipment and switchgear(which will need to be accessible at all times incase of emergency).

I employees and self-employed people who work on the construction site;

I other people who may visit the site during the course of their work, egdelivery drivers, service engineers etc;

I other people including members of the public who may be affected by thework activity.

8 Some regulations give detailed requirements for the construction industry,for example the CDM Regulations’. These Regulations place duties on:

I clients;

I designers;

I those planning and co-ordinating the work (planning supervisor andprincipal contractor);

I contractors who carry out the work.

Other regulations set out requirements which apply across all industries, forexample the Electricity at Work Regulations 198g2, and the Provision and Use ofWork Equipment Regulations 19923.

9 Those who have duties under health and safety legislation should be awareof the hierarchy of risk control which underlies the modern approach to healthand safety management. Some of the main principles of this hierarchy are:

I where possible, avoid risks altogether (eg, change the design, workmethod, equipment or working environment);

I assess the extent of any risks which remain;

I reduce these risks to an acceptable level, preferably by using solutionswhich combat the risk at source;

I replace the dangerous by the non-dangerous or less dangerous (eg, usepneumatic power tools in a wet environment);

I give priority to controls which will protect all workers rather than a numberof individuals. For example, a reduced low voltage, site distribution systemsuch as one which is 11 OV centre tapped to earth (11 OV CTE), will ensurethat if distribution cables are damaged the risk of fatal shock to anyone inthe vicinity is virtually eliminated;

I provide information, training and instruction to combat any risk which remains.

230/l 10 vok transformer

Baffery-operafed Ml

I the principles of risk control outlined in paragraph 9;

I the characteristics of the system selected;

I the voltage requirements of the plant andequipment to be used.

28 Most electric shocks are between a live part andearth as a result of a fault or damage to plugs, cables orequipment. Long experience in the UK has shown thatthe use of reduced low voltage portable electrical toolsand equipment (eg, 11OV CTE) on building sites willeffectively eliminate the risk of death and greatly reducethe degree of injury in the event of an electrical fault(see paragraph 29). Therefore the best way to reducesuch risk is to keep the supply voltage to the lowestwhich is necessary for the job to be done. This combatsthe risk at source, and helps ensure the protection of allworkers on site.

29 When deciding on the site supply to work areas,remember that:

I where risks are particularly high, eg on awaterlogged site or in confined spaces, the use ofpneumatically powered tools will eliminateelectrical risks;

I where electrically powered tools are used,battery-operated tools are the safest;

I a SELV system (sometimes called a safety extralow voltage system) which is separated from earthand which limits the voltage supplied to amaximum of 5OV, can be used for lighting andsome power tools, (however this may beimpractical for motor driven equipment fed bylong leads);

a reduced low voltage system, which delivers1 IOV to the equipment, designed so that themaximum voltage to earth is only 55V in a singlephase system (65V in a 3 phase system), is saferthan using 230V;

where mains voltage (230V) is used to supply site

PLANNING ‘ T H E W O R K

14 Many of the risks can be avoided by carefulplanning before the work starts. The CDM Regulations’provide a framework for the management of these risks.Even where these Regulations do not apply, the advicein the following paragraphs will help contractors andothers to comply with their general duties under otherhealth and safety legislation.

15 Where the CDM Regulations apply, the client willneed to first appoint someone to plan the work (theplanning supervisor). Clients should then provide themwith information relevant to health and safety. Thisincludes information about present or previous use ofexisting buildings, land or plant etc at the site where theconstruction work is to be carried out.

16 Information such as drawings and wiring: diagrams for the existing electrical installation, plans

&owing the location of electrical services, or previoussurveys of the land and structures may be to hand, forexample in an existing health and safety file. If not, theclient (or someone acting on the client’s behalf) willneed to make reasonable enquiries to obtain thisinformation which will be needed by both the designersand the contractors. This might mean commissioning asurvey of existing premises to determine, for example,which electrical services will remain live while the workis carried out, or to obtain information from the utilitieson the location of underground services.

17 Designers should use this and other relevantinformation when deciding how best to control risk.They should:

I first consider if the risk can be avoided, egarrange for overhead lines to be moved or sitethe structure away from them;

I specify the use of particular equipment such asair powered, or cordless tools for those locationswhere the work will be in wet or confinedconditions;

Locahon of electrical services

5

Plugs/sockets

Selection of equipment for the temporary sitedistribution system

32 Equipment which is designed to withstandconditions on a construction site should be selected.Particular attention should be paid to any restrictions onuse specified by the manufacturer.

33 Site distribution units should be designed andmanufactured to a suitable standard, eg BS EN 60439-4, Particular requirements for assemblies forconstruction sites (ACS)“. Units having the followingfeatures will generally be suitable:

I flexibility in application for repeated use onvarious contracts;

I design for ease of transport and storage;

I robust construction that will resist damage;

I provision of lockable switches and means ofisolation.

34 Socket outlets should be suitable for use onconstruction sites, eg those specified in BS 4343 (BS EN60309-2) Plugs, socket-outlets and couplers forindustrial purposes’*. Sockets for domestic use (eg, BS1 36313) are not designed for site use.

Staff appointments

35 Before starting work the principal or maincontractor should appoint people responsible for sitesafety. It will help if their responsibilities are set outclearly in writing. Where the CDM Regulations apply,anyone appointing or engaging a designer to carry outdesign work, or a contractor to carry out or manageconstruction work, should be satisfied that those theyintend to appoint are competent and adequatelyresourced for health and safety purposes.

36 All staff will need to be competent to carry out thetasks for which they will be responsible. When deciding

12

I

earthing requirements or earthing system to beused;

the supply to and siting of heavy duty equipment,eg tower cranes;

the installation and commissioning of thetemporary site distribution system, in particularthe siting and protection of metering equipmentand switchgear, distribution boards and supplycables;

the way in which the system will be modified orextended as the work progresses;

operation of the temporary site distributionsystem (who will control, operate, and maintainthe electrical distribution systems and how thiscan be done safely);

use of plant and equipment connected to thedistribution system (consider who will use theplant and equipment, and how such use will becontrolled. Who will be responsible for plant andequipment maintenance?);

provision of lockable switches and means ofisolation;

use of existing permanent systems as a supplyfor plant and equipment;

Typcal equipment

if refurbishment works are to be carried out,identification of parts of the system which arelive;

I commissioning and handover arrangements forcompleted buildings or installations.

Most of these issues are covered in later paragraphs.

20 Where the CDM Regulations apply, a planningsupervisor should be appointed and a pre-tender sta(health and safety plan should be prepared. The planshould include details of health and safety risks(including electrical risks) and other relevant

7

T H E S A F E T Y O F T H EE L E C T R I C A L INSTXLLA’I-ION

Smali generators

Generators

38 A supply from an electricity supply company is notalways available. In these instances the electricitysupply for the site can be provided by an ac generatingset. Care is needed to ensure that the generator isinstalled safely, and expert advice may be needed,particularly on earthing.

39 For small scale work, or in locations remote fromthe site supply, portable generators (with outputs of upto 10 kVA) are often used. For short time work (eg, lessthan one day), these generators need not be earthedprovided that they are only used with Class II (doubleinsulated or all-insulated) tools or equipment.

40 The smaller, single phase generators used for1 IOV supplies, (ie those with ratings up to about 5 kVA)need not be earthed, if all the equipment in use isdouble insulated, or if it supplies only one item of‘earthed’ equipment. However, the equipment should bebonded with the frame of the generator. (Bondinginvolves connecting items of metalwork together in away that is electrically continuous.)

41 In all other circumstances, a suitable earth shouldbe provided.

42 When larger generators are used (output in excessof 10 kVA), the generating set may be either single or 3phase. Particular care is needed to ensure that thesystem is installed safely and this may require specialistadvice. Matters to consider include the following:

I generators need to be earthed, by bonding theneutral to the frame and connecting the frame toearth;

I the impedance of the bonding needs to be lowenough to ensure correct operation of protective

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Overhead lines and underground cables

23 If there are existing overhead lines or cables onsite, they should, where possible, be made dead or re-routed before work starts. The owners of the overheadlines or cables will need to agree to this. They may be:

I the site owner:

I the developer;

I the local authority;

I the local electricity supplier;

I the railway line owner where the site is near anelectrified railway line.

24 Early contact with the owners is recommended sothat this work can be completed before constructionwork begins, If the overhead lines and cables cannotbe made dead or re-routed, precautions should be putin place to ensure that they are not approached ordisturbed. The owners may also have detailedrequirements for work in the vicinity of their equipment.

25 Further information is given in HSE’s guidancenote GS 6 Avoidance of danger from overheadelectrical lines 7.

26 The location of any underground cables shouldbe confirmed and the route marked as recommendedin HSE’s booklet HS(G)47 Avoiding danger fromunderground service9. Danger will be avoided if theprecautions recommended in that document arefollowed. Similar precautions should be taken forcables that are subsequently installed as either part ofthe temporary site supply or as part of the permanentinstallation. Also see paragraph 60.

The supply voltage

27 When planning and installing the site supply, thefollowing need to be taken into account:

Worker usmg a cable avoidance tool

9

Earth eiectrode

46 Many electricity suppliers’ systems use protectivemultiple earthing (PME). (In these systems neutral andearth are combined.) Where a PME system is used allmetalwork, including structural metalwork, must bebonded together (connected together in a way that iselectrically continuous). This is generally difficult toachieve on a construction site for a variety of reasons,particularly where steelwork is being added in thecourse of the work, where steelwork has been treatedagainst corrosion, or where individual metal framedportable buildings or cabins are used. Therefore mostelectricity suppliers will not connect the site electricalsystem unless there is an adequate alternative earth.The use of an earth from a PME system is not allowedfor the electrical supply to site caravans.

47 There are several alternative methods of providinga secure and effective earth. On a construction site asystem that uses earth electrodes is most commonlyused and will ensure that fuses etc will operate if there isa fault. Where necessary, specialist advice should besought to ensure that there is adequate electricalprotection. Detailed advice on earthing is contained inBritish Standard 7430 Code ofpractice for earthing14.

48 If the work involves extending an existing site orstructure, the existing electrical installation may besupplied from a PME system. In these circumstances itis strongly recommended that temporary site distributionsystems which, for their effective earthing, depend onthe provision of their own earthing electrodes, are keptseparate from the PME system.

49 Fixed cable armouring and metal conduit can beused as a protective (earthing) conductor. Flexiblemetallic conduit should not be used as the only earthingconductor; it needs to be bonded (metalwork connectedtogether in a way that is electrically continuous) and aseparate protective (earth) conductor will be necessary.

50 The effective operation of any electrical protectiondepends on a low resistance earth path in the event of afault. Joints in the earth path are particularly vulnerableto damage so there should be good electricalconnection between the various components, egbetween conduit, cable glands, and the equipment.

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offices and welfare facilities, it is recommendedthat the system is protected with a residualcurrent device;

I if, having considered the hierarchy of risk control,a mains voltage (230V) supply is selected forportable tools and equipment, additionalprecautions must be provided to reduce the riskto an acceptable level (see paragraph 70).

Technical details of the reduced low voltage systemscommonly used in the UK, and the safety benefitsarising from their use are given in Appendix 2.

30 Many construction sites will require supplies atseveral voltages. The following are the recommendedmaximum voltages for particular applications:

I portable hand lamps for use in confined or dampsituations: 25V single phase;

, I other portable hand lamps: 50V;

I site lighting other than fixed floodlighting: 11OVreduced low voltage single phase;

I portable and hand-held tools and transportableequipment up to about 3.7kW (5hp): 1 IOVreduced low voltage, single or 3 phase;

I installations in site offices, huts, other buildingsand fixed floodlighting: 230V single phase;

I fixed or moveable heavy duty plant (eg, towercranes etc): 400V 3 phase;

Note: Some specialist equipment (eg, submersiblepumps) may not be available in a range of voltages.

31 Further guidance on the standards for electricalinstallations on construction sites is contained in theBritish Standards BS 7375 Code ofpractice fordistribution of electricity on construction and buildingsite@ and BS 4363 Specification for distributionassemblies for electricity supplies for construction andbuilding sites’ O.

Festoon lighting

11

Distribution assembly with circuit breakers

Underground cab/e marker

various locations on the site during the constructionphase The temporary site distribution system is alwaysremoved when site work is completed as it is then nolonger required. Removal may begin on completion andcommissioning of all or part of the permanent, fixedinstallation.

55 Although the site distribution system may be onlytemporary, the harsh conditions on site require that it isto a high standard. Equipment must be adequatelyprotected against damage and contamination.

56 Switchgear and metering equipment should beprovided with secure accommodation, and protectedfrom adverse environmental condrtions. It shouldpreferably be located at a place where it is less likely tobe damaged. Make sure that switchgear, and inparticular the means of turning off the supply, isaccessible at all times in case of emergency.

57 The use of correctly rated fuses and/or circuitbreakers is essential for all the supplies on site.

58 Makeshift arrangements, such as unprotectedwiring, taped and twisted cable joints, are oftendangerous and should not be permitted. All wiring onsite should be installed to appropriate standards, eg seeBS 7671 Requirements for electrical installations16 andBS 7375 Code of practice for distribution of electricity onconstruction and building site@.

59 Construction site distribution units such as thosespecified in BS 737!Y1~, BS 43631° and BS EN 60439-4’ l,have the facility for plugging in further extensions. Suchsystems should only be installed or altered by peoplewith the necessary knowledge and experience of theuse of such systems. All other site installations which arenot designed as plug-in systems need to be installed bya competent electrician. After installation, tests shouldbe carried out to verify that the system is safe. Detailedadvice is given in BS 7671 l6 and the associatedguidance.

60 Distribution cables should be located where theyare not likely to be damaged by site activities. Theyshould be kept clear of passageways, ladders and other

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whether or not people are competent, the following areimportant:

I training and instruction;

I experience;

I knowledge of the risks involved;

I an understanding of the work and an ability tocarry it out safely.

37 Having given people specific responsibility forsafety matters, it is important that both the individualsconcerned and others working on the site are aware ofthe extent and limitations of these responsibilities, andwhat arrangements there are to cover the absence ofthese staff (eg, during holidays). A good way of makingthese matters clear is to issue written instructions settingout individual responsibilities and how the safetyarrangements will work in practice. Instructions and

( rules may form part of the relevant health and safetyplans

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Extension iead

Portable equipment

66 Portable equipment and its leads face harshconditions and rough use. Equipment is likely to bedamaged and may become dangerous. Modern doubleinsulated tools are well protected, but their leads andplugs are still vulnerable to damage and should beregularly checked. See the table on page 27. It isessential that the type of equipment selected is suitablefor use on a construction site, and that any restrictionson use given by the manufacturer are followed.

67 The site supply voltage will often influence thechoice of equipment. Where the supply is 230V orabove, contractors can themselves eliminate or reducethe risks by selecting cordless tools or tools whichoperate from a reduced low voltage supply, (eg, 11OVsystems which are centre tapped to earth). For lighting,lower voltages can be used and are even safer.

68 There have been fatal accidents where 11OVequipment fitted with plugs designed for a 230V systemor damaged BS 4343 (BS 60309-2)12 11 OV plugs havebeen plugged into 230V supplies. To avoid danger,plugs and sockets used on the reduced low voltagesystem should not be interchangeable with 230V(mains) plugs and sockets. Plugs and sockets to thestandard BS 4343 (BS EN 60309-2) Hugs, socket-outlets and couplers for industrial purposes12, are non-interchangeable and are colour coded to indicatevoltage (violet for 25V, white for 5OV, yellow for 1 lOV,blue for 23OV, red for 400V). These industrial plugs andsockets are more robust than domestic (BS 136313) 13amp type equipment which is not designed for use onconstruction sites.

69 Cables with solid conductors (non-stranded) aredesigned for use in fixed installations. The conductorsinside are brittle and liable to break if bent, so theyshould not be used as either extension leads orreplacement cables for portable equipment.

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devices (fuses, circuit breakers etc). Seeparagraph 51;

I sensitive earth fault protection may be necessaryif earthing conditions are difficult.

43 Further guidance on earthing and bonding ofgenerator systems can be obtained from the supplier ofthe equipment, and detailed advice can be found in BS7375 Code of practice for distribution of electricity onconstruction and building sites9 and BS 7430 Code ofpractice for earthing14.

44 Generators should be connected and operated sothat they are separate from the public supply systemunless agreement has already been obtained in writingfrom the electricity supplier. (See the ElectricityAssociation’s recommendation G 59-1 15.)

Large generator

Earthing the site supply

45 Electrical safety often depends upon theexistence of effective earthing. The responsibility forensuring that the electrical earthing is effective restswith the person in charge of the site, not with theelectricity supplier. Typical PME maux serwce Intake position and

equipment showing earth electrode (rod)

Securewaterproofenclosure

Meter

Meterterminals

Connectorblock

cut out Urlli(with fuse)

lncomlngservice

cable (PME)

Mete; tails

Consumerunit

Residualcurrentdevice (RCD)

Site MC&or fuses

100 Ampdouble poleswitch

Cables to siteInstallations

Site earthconnection

Earthelectrode(rod)

*Note:No

connectionbetween

incomingPME earth

and siteinstallation

earth

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I positioning them where they are less likely to bedamaged, (eg, run them at ceiling height inside abuilding); and/or

I protecting them inside impact resistant conduitwhere appropriate; or

I using special abrasion resistant or armouredflexible supply leads where appropriate.

(c) selecting tools that are designed for trade andwork use. Double insulated equipment is stronglyrecommended where it is necessary to use amains voltage supply, because the toolsthemselves are less likely to give rise to danger.(Danger can still arise, however, if the cables,plugs or equipment casing are damaged). Anyrestrictions on use set out in the manufacturer’sinstructions should be observed.

(d) regular maintenance checks which should bemade of all electrical equipment. These shouldinclude:

A distribution board with an RCD

checks by the user each time the tool is used;

formal visual checks by a trained person on aregular basis (see paragraphs 80 to 82 and thetable on page 27);

combined inspection and testing by a trainedperson at suitable intervals depending on the riskof damage and the potential for injury. (Seeparagraphs 84 to 85 and the table on page 27.)

Residual current devices (RCDs)

71 Due to the delicate nature of an RCD, it is not idealfor use in the rough environment of a construction site. Itmay not be possible to ensure that the housing for theRCD is maintained to the quality required in theselocations, and control over the number of times the testbutton is operated may be difficult. The manufacturersof RCDs do not generally recommend them to be fittedon portable apparatus which may receive mechanicalshock or on equipment which might vibrate.

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Additional electrical connections between the variousmetal parts may be necessary to provide this lowresistance path, ensuring reliable operation of fuses etc.

51 Guidance on earth impedance values is containedin BS 7671 Requirements for electrical installations 16.Specialist advice on appropriate values may benecessary. (Note: The values in the British Standard arebased on a nominal voltage to earth of 240V. Fordifferent voltages to earth, eg reduced low voltage, theimpedance values will need to be adjustedaccordingly). Earthing should always be tested after anitem of equipment has been installed, paying particularattention to the continuity of protective (earthing)conductors, as well as to the polarity and to insulationresistance. See BS 7671 l6 and paragraphs 76 to 78 ontesting.

Earthing equipment connected to the supply

: ?’Equipment that is either double insulated,

constructed with two layers of insulation to provideelectrical protection in case of damage to the outerinsulation) or all insulated, (constructed with reinforcedinsulation) does not need, and will not be fitted with ameans of connection to earth. Double insulatedequipment is marked with this symbol:

and will therefore be supplied with a two core cable.Equipment which is not double insulated or all insulatedmust be earthed. A three core cable will be needed.

53 If extension leads are used, it is stronglyrecommended that these are always of three coreconstruction having a separate protective (earth)conductor. This will ensure that the supply to tools whichare not double insulated always includes an earth.

The temporary site distribution system

54 This is the cabling system and equipment installedto distribute and supply electricity to points of use at the

Bonded conduit, cable gland and equipment

17

are kept on site. (See BS 7671 l6 and associatedguidance for details of the appropriate tests.)

77 Electrical distribution systems on constructionsites (excluding those within site offices) should be re-tested every three months or more often as experiencedictates. This applies to the temporary fixed installationand to any pre-existing or new permanently fixedinstallation which may be used for the constructionactivities. On many sites it is often found necessary toinspect the installation much more frequently. Circuits orapparatus which are not satisfactory should be removedfrom service without delay and remedial action takenbefore they are used again. Installations in site officesexperience more harsh conditions than officeinstallations in a non-construction environment. Theyshould be tested regularly - a period of no more than 12months is recommended, as well as each time the officeis moved.

78 Routine testing of the installation and repair ofdefects should normally be carried out by electriciansother than those doing the construction work. This isbecause the pressures that are often placed upon siteworkers to meet installation deadlines may be such thatthe routine testing and repair is not given its properpriority.

Maintaining portable electrical equipment

Typical equipment

79 On construction sites, the risks from damaged orfaulty portable electrical equipment are high, and needto be managed and controlled by setting up anappropriate maintenance system. HSE’s bookletHS(G)lO7 Maintaining portable and transportableelectrical equipment *O gives detailed general advice onthe electrical safety aspects of maintaining portableapparatus. The maintenance system will need toinclude:

I formal visual inspections on a regular basis;

I checks by the user:

I combined inspection and electrical testing wherenecessary.

services. If they need to cross a site roadway or walkway they can be put intoducts with a marker at each end of the duct. If the roadway is used by vehiclesthe duct should be at least 0.5 m below the surface. A record of the location ofany underground cables, using maps or plans showing the line and depth ofsuch cables will be invaluable in avoiding damage as the work progresses.Alternatively cables properly protected can be carried at a suitable height abovethe roadway or footway. A goalpost type system may be required - see HSE’sguidance note GS 6 Avoidance of danger from overhead electrical lines7.

61 All fixed distribution cables which carry 400V or 230V on a constructionsite are recommended to be of a type which has metal sheath and/or armourwhich is continuous and effectively earthed. The metal sheath and/or armourshould be protected against corrosion.

62 Site offices and fixed floodlighting will generally require 230V supplies.Installations within site offices and other buildings should be to a suitablestandard - see BS 7671 Requirements for electrical installations16. Theequipment selected and installed should be suitable for the environment in whichit is used.

63 It is strongly recommended that, on larger sites, any existing or newpermanent fixed supply is not used to supply contractors’ equipment during theconstruction work. This will minimise unauthorised interference with thepermanent fixed installation.

Moveable plant

64 Plant such as lifts and hoists which may be relocated occasionally duringthe work is recommended to be supplied by armoured cable. If, in the course ofthe construction operations, the plant is to be relocated, a safe method of workmust be adopted. This will include turning off the supply and disconnecting thecable before the plant and cable are moved. Plant which is moved frequently(eg, a cement mixer) should be connected to the supply by a flexible cable withprotective braid and abrasion-resistant sheath. Cables will need to be suitablylocated and adequately protected so that they will not be damaged.

65 If equipment has a high current requirement (current ratings greater than16 amps), arcing can occur if the plug and socket are separated under load,causing burns or other injuries. Ways of isolating the supply should be providedto ensure that the supply is switched off before the plug and socket areseparated. Examples of suitable equipment can be found in BS 4343 (BS EN60309-2) Plugs, socket-outlets and couplers for industrial purposes12, whichallows for such plugs to be interlocked so that they cannot be withdrawn unlessthe supply is switched off at the socket.

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84 Testing can detect faults such as loss of earth continuity, deterioration ofthe insulation and internal or external contamination by dust, water etc. All ofthese faults are likely to happen on a construction site, because of the arduousenvironment, and they may not be picked up by user checks or formal visualinspections. It is therefore important that testing is carried out by a persontrained to do so at a frequency appropriate to the type of equipment and therisks.

85 In addition to routine testing as part of the planned maintenanceprogramme, combined inspection and testing is also recommended:

I if there is reason to suspect the equipment may be faulty, damaged orcontaminated but this cannot be confirmed by visual inspection; and

I after any repair, modification or similar work to the equipment, when itsintegrity needs to be established.

86 The following table gives guidance on the suggested frequencies of userchecks, planned formal visual inspections and combined visual inspection andtesting of portable electrical equipment. It is based on practical experience andis designed to assist those setting up a maintenance regime for the first time. Thefrequencies should be appropriate to the risks on site. They should be reviewedoccasionally, using the results of previous inspections and tests to see whetherthe frequency can be decreased or should be increased.

26

Use of mains voltage equipment

70 When mains voltage equipment is used onconstruction sites, the risk of injury or death arising fromthe use of damaged or faulty equipment, leads or plugsis unacceptably high unless special precautions aretaken. The precautions must reduce the risk to anacceptable level, taking into account the constraintsregarding RCDs mentioned in paragraphs 71 to 75.Reasonably practicable precautions include:

(a) protecting people who may receive an electricshock by fitting non-adjustable residual currentdevices (RCDs) with a rated tripping current of 30mA. RCDs should be installed either at thedistribution board* which feeds the mains supplysockets or at the fixed mains supply socket. Ineither of these positions they will provide protectionfor both the cable and tool. RCDs fitted close to thetool only protect the tool. RCDs should be:

&tens/on iead wth RCD

“m installed in a dustproof and weatherproofenclosure (see the manufacturer’s instructions) ordesigned for use in dusty and outdoorenvironments;

I protected against mechanical damage andvibration:

I checked daily by operating the test button;

I inspected weekly together with the equipment it issupplying during the formal visual inspection;

I tested every three months by an electrician usingappropriate electrical test equipment. Note: Thetests should not be carried out on RCDs at a timewhen loss of power may adversely affect otherwork activities.

*Note: See paragraph 75 on unwanted tripping

(b) reducing the risk of flexible supply leads beingdamaged by:

21

87 Higher risk equipment (230V or above) needs to be checked, inspectedand tested more often than lower risk equipment (11OV or less).

88 Damaged equipment should be taken out of service immediately andclearly labelled as defective. Users should not attempt makeshift repairs. Repairsshould be carried out by competent electricians.

D E M O L I T I O N

89 If the demolition process itself requires a supply of electricity, the supplyshould be independent of any existing electrical installations in the buildingbeing demolished.

90 It is important to locate existing services at the planning stage of ademolition project. Danger will be avoided if all electricity supplies are cut offbefore demolition begins and proved dead by an electrically competent person,eg electrician or electrical engineer. Demolition plans need to be discussed withthe owners of cables in case either they are intending to re-use these cables inlater redevelopment or the cables supply an area other than the demolition site.See paragraphs 23 to 26.

B U I L D I N G A L T E R A T I O N

A N D R E F U R B I S H M E N T

91 When buildings are altered or extended, risks can arise from the use of, orcontact with the existing electrical installation and plant or equipment connectedto it. Even for small jobs it is recommended that before work starts the existingwiring is surveyed to ensure that it is safe and the relevant circuits have beenidentified. Particular care is needed to avoid damage to cables or equipmentthat may be energised, or might subsequently be made live. The potential forconfusion and danger will be avoided if old wiring and equipment no longerrequired is removed as early in the project as practicable.

92 If the work comprises light refurbishment, shopfitting etc, where onlylighting and hand tools are to be used and the possibility of damage to theirleads is low, the existing electrical installation may be used as a supply. This isproviding that suitable means of connection are available. In thesecircumstances either the voltage should be reduced to a safe level, eg 1 IOV CTEor the system should be protected using RCDs (see paragraph 70(a)).

28

to operate, or is faulty, this will not be indicated and theworker may remain unaware of the danger. They onlyprotect against earth faults, and will not operate whenthere is no connection to earth, ie if current is passing l �io . 2, l 0from live to neutral. So it is possible to suffer an electricshock and injury even though the RCD is operatingcorrectly.

72 An RCD does not guarantee safety. If an RCD fails

73 It IS therefore not possible to place total or neartotal reliance for personal safety on RCDs. In contrast,the use of passive systems, such as reduced lowvoltage, can give reliable protection against fatal electricshock.

74 The installation of an RCD will not make a systemsafe if it has been poorly designed or installed. An RCDis no substitute for a properly installed and protectedelectrical system with an efficient earth. RCDs forprotecting people have a rated tripping current(sensitivity) of not more than 30 mA (and a non-adjustable rated operating time of 200 milliseconds (ms)at a test current of 30 mA, and 40 ms at 1.50 mA). Seethe appropriate British Standard, BS 429317 (General),BS 7071 la (portable) and BS 72881g (incorporated insocket outlet).

Mans distribuim assembly with RCDs

75 On sites with a larger temporary distributionsystem, if a 30 mA RCD was fitted at the point at whichelectricity is supplied to the site, this could lead tounwanted tripping. (Each fault or other earth leakagewithin the site distribution system could cause the RCDto trip, therefore turning off the supply to the whole site.)Such tripping can also occur when RCDs are fitted to anintermediate distribution system. To reduce thepossibility of unwanted tripping, the non-adjustable30 mA RCDs should be fitted to individual circuits.

Maintaining the electrical installation

76 It is strongly recommended that temporary sitedistribution systems, new permanent installations andextensions or alterations to an existing system should betested on completion. Also, a certificate of adequacyneeds to be issued by the person carrying out the test. Itis also recommended that copies of these certificates

23

identified and held by either the main contractor or a subcontractor’sdesignated supervisor;

I the use of temporary electrical supplies is minimised during plantcommissioning;

I adequate supervision is taking place, and agreed procedures are beingfollowed.

9 5 Systems should not be made live until all enclosures are complete in allrespects. It is strongly recommended that newly commissioned equipment whichmay be mistaken for non-commissioned equipment is identified as live by aprominent temporary warning notice. This notice should show the commissioningcontractor’s name, site telephone number and date when it was first made live.

96 It is strongly recommended that circuits which are not in use are locked offand the keys held in safe keeping by a responsible person. Doors toswitchrooms and covers to fuse and miniature circuit breaker (MCB) boardsshould also be locked shut, and the keys held by a responsible person.

SAFE W O R K I N G P R A C T I C E S

97 Safe systems of work should be followed when working on an electricalinstallation. Guidance is given in HSE’s booklet HS(G)85 Electricity at workxafeworking practices 21.

98 Electricians working on high voltage systems should be specially trained.Depending on the complexity of the system and the voltages in use, permit-to-work systems may need to be used, together with the provision of lockableswitches and other means of secure isolation.

X~EATMENT 0~ E L E C T R I CS H O C K V I C T I M S

30

99 The Management of Health and Safety at Work Regulations 1 99222 requireemergency procedures to be planned for. These should include:

I adequate provisions being made for calling the emergency services;

80 The most important precaution is the formal visual Inspection because thiscan detect about 95% of faults or damage. Site management should ensure thatregular visual inspections are carried out by sensible (competent) members ofstaff (see paragraph 36). Such staff should be given sufficient training to enablethem to detect signs of faults or damage. These inspections could be includedas part of the routine site safety checks carried out by site managers and sitesupervisors. Allocate time to enable them to carry out the inspections.

81 Those using electrical equipment should be given basic training so thatthey know how to visually check the equipment they are using. It isrecommended that they look at 230V portable equipment and RCDs every day orat the start of every shift (if the site is in use 24 hours a day). They should beinstructed to report any faults immediately so that the equipment can be takenout of use and repaired.

82 The following can be seen easily and will normally be picked up during theformal visual inspections and the checks by the user. Make sure that:

I bare wires are not visible;

I the cable covering is not damaged and is free from cuts and abrasions(apart from light scuffing);

m the plug is in good condition, ie the casing is not cracked, the pins are notbent or the key way (socket) is not blocked with loose material;

m there are no taped or other non-standard joints in the cable;

m the outer covering (sheath) of the cable is gripped where it enters the plugor equipment. The coloured insulation of the internal wires should not bevisible;

m the outer casing of the equipment is not damaged or loose and all screwsare in place;

m there are no overheating or burn marks on the plug, cable or theequipment;

m RCDs are working effectively (the test button should be pressed daily).

83 It is important that electrical equipment is regularly serviced in line with themanufacturer’s instructions. If tools and equipment are hired, such maintenancewill normally be carried out by the owner of the equipment. In such casesarrangements should be made to return the equipment, or make it available formaintenance, in line with the owner’s schedule.

25

AJTENDIX 1:TEGI~IJYI-I~N

1 The following summary outlines the main legal requirements which apply tothe use of electricity on construction sites. The list is not complete and does notgive a definitive interpretation of the law. It summarises the main issues to beborne in mind when carrying out such work. Full details of the legislation can befound in the documents referred to at the end of this guidance.

The Health and Safety at Work etc Act 1974

2 The Health and Safety at Work etc Act 19746 places duties on employers,employees and the self-employed to ensure, so far as is reasonably practicable,the safety of people involved in work activities, and those who may be affectedby work activities.

The Management of Health and Safety at Work Regulations 1992

3 The Management of Health and Safety at Work Regulations 1992** requireemployers and the self-employed to assess the risks arising from work activities.They should do this with a view to identifying the measures which need to betaken to comply with relevant health and safety legislation, therefore eliminatingrisks where possible and controlling those which remain

The Construction (Design and Management) Regulations 1994

4 The Construction (Design and Management) Regulations 1994’ apply tomany construction projects and set out requirements in relation to their designand management. They place responsibilities on all those who can contribute toimproving health and safety including clients, designers and contractors.Hazards should be identified, and risks eliminated, or where this is not possible,reduced by action during the design, planning and execution phases of theproject.

5 The Regulations create the two key functions of planning supervisor andprincipal contractor to co-ordinate health and safety during the design andconstruction phases. The Regulations also provide for health and safety planswhich draw together the health and safety issues in relation to the project. Thepre-tender stage health and safety plan should set out what has been done toeliminate or reduce risks (including electrical risks) during the design phase andprovide relevant information for the principal contractor. The construction phasehealth and safety plan prepared by the principal contractor should set out howthe construction work will be managed to eliminate and reduce risks.

32

&PENDIX 2:T E C H N I C A L NOTES 0~R E S I D U A L C U R R E N TD E V I C E S A N D R E D U C E DL O W VOL’I’AGE S Y S T E M S

Residual current devices (RCDs)

1 An RCD is an electro-mechanical device which may be likened to a currentbalance. It compares the current flowing into the system with the current flowingout of the system. When the system is fault free, these values are the same, andthe RCD continues to allow the current to flow. When the levels differ by a pre-setvalue (the rated tripping current value of the device) or more, the RCD will openrapidly, therefore interrupting the electrical supply.

2 The RCD is sensitive to very small losses of current. It does not limit thecurrent flowing in the event of shock, it limits the time for which that current flows,therefore minimising injury. If an RCD fails to operate the current will continueflowing, possibly dangerously.

3 RCDs can also be subject to unwanted tripping. This is where the RCDtrips frequently in the absence of a detectable fault. The cause may, for example,be due to ‘leakage’ currents from items such as information technologyequipment. The resulting loss of supply causes inconvenience to users of thesystem, and increases the likelihood of the device being defeated in some way,so rendering the system without protection.

Reduced low voltage systems

4 These are electrical supply systems in which the maximum voltage to earththat can occur in the event of a fault or damage to the system is reliably limited toa value which is unlikely to cause danger to people. Unlike residual currentdevices (RCDs), reduced low voltage systems are passive systems as they donot rely on the operation of a sensitive electro-mechanical device to ensuresafety.

5 Cordless (battery-operated) hand-held tools are one example of reducedlow voltage equipment, but these have limitations on power output and durationof operation.

34

S U G G E S T E D I N S P E C T I O NA N D ‘I’ES’I’ F R E Q U E N C I E SF O R ELEC’IRICALE Q U I P M E N T O N ACONS’I’RUC’TION S I T E

EquIpmeWapplication

Voltage Usercheck

Battery-operatedpower tools andtorches

25V Portable handlamps (confined ordamp situations)

5OV Portable handlamps

11OV Portable andhand-held tools,extension leads, sitelighting, moveablewiring systems andassociatedswitchgear

230V Portable andhand-held tools,extension leads andportable floodlighting

230V Equipment suchas lifts, hoists andfixed floodlighting

RCDS Fixed**

Equipment in siteoffices

Less than 25volts

No

25 voltSecondary

winding fromtransformer

No

Secondarywinding centretapped to earth

(25 volt)

No

Secondarywinding centretapped to earth

(5.5 volt)

Weekly

230V Supplyfuses or MCBs

Weekly

Daily/everyshift

230 volt Officeequipment

Monthly

Formalvisual

inspection

No No

No No

No Yearly

Monthly Before firstuse on siteand then 3

monthly

Weekly Before firstuse on siteand thenmonthly

Monthly Before firstuse on siteand then 3

monthly

Weekly *Before firstuse on siteand then 3

monthly

6 Monthly Before firstuse on siteand then

yearly

* Note: RCDs need a different range of tests to other portable equpment, and equipment deslgned tocarry out appropriate tests on RCDs WIII need to be used** It IS recommended that portable RCDs are tested monthly

27

Reduced low voltageA system In whtch the nominal phase-to-earth voltage does not exceed 63.5V and the

nominal phase-to-phase voltage does not exceed 1 IOV.

3 phase

Reduced low voltage source 3 phasef T . Ll

RLV

7 Source earth.

Protectiveconductor

System phase-to-phase voltage notexceedrng 110 volts.

System phase-to-earth voltage notexceeding 63.5 volts . . . . . i Sate rnstallation

All exposed conductive parts are I I I I i

connected to the protective conductor ; Drstrrbutionequrpment

Distribution :equrpment i

Exposed conductrve parts

Figure 1

Single phase

Reduced low voltage source single phase

tEj::

RLV

Protectiveconductor

System line-to-lrne voltage notexceedrng 110 volts.

System lrne-to-earth voltage notexceeding 55 volts.

All exposed conductive parts areconnected to the protective conductor Distnbutron equrpment rnstallatton

Ffgure 2

36

HANDOVER A N D

C O M M I S S I O N I N G W O R K

93 This section deals with the permanent, fixedinstallation in the building or structure underconstruction, As parts of the installation are completed,they may be progressively commissioned and broughtinto use. Risks will arise unless subcontractors and theiremployees are kept up to date about the state of thejob, namely whether electrical systems have beenenergised, whether they are capable of being energisedor whether plant is still safe to work on.

94 These risks will be avoided if the main contractorprepares in good time an agreed plant commissioningprogramme. The plan can then be monitored byensuring that:

I

I

the programme is brought to the attention of allmechanical and electrical subcontractors;

regular (eg, weekly) commissioning meetings areattended by all subcontractors, to record pastprogress, to arrange for the following week’swork, and to manage any programmedivergencies;

key information notes are issued immediately aftereach meeting;

subcontractors’ written plant commissioningprocedures are checked where applicable;

access to the site by plant suppliers’ specialiststaff is controlled and information regarding newlycommissioned plant is passed on;

checks are made to ensure that the required workhas in fact been completed;

secure means of isolation exist for each part ofthe installation on which work is being carried out.All padlocks and keys used should be clearly

isolator in locked off position

29

I wear rubber or plastic insulating gloves, ifavailable, to pull the casualty free; or

I if rope is available, without touching the casualty,loop it around the feet or under the arms and pullthe casualty free.

Ensure there is no more danger. If the casualty seemsunharmed, rest and reassure them and refer to a doctoror a nurse. However, if the casualty is unconscious,check breathing and pulse. Send for help immediately.Resuscitation may be needed.

First aid action

Step A

Open the airway by:

I turning the casualty on his/her back;

I lifting the jaw and tilting the head back to open3

the airway;

I carefully removing any obvious debris frominside the mouth.

Step i3

Check breathing by:

I looking to see if the chest rises and falls;

I listening for breaths;

Step A

Step B

I feeling breaths on your cheek.

Step C

Check circulation (pulse):

I find the pulse by placing your fingers to the sideof the voice box and pressing down gently.

Step C

38

I workers who are expected to help in the event of an accident beinginstructed on the procedure to follow to isolate the supply;

I some of the workers on site being given practical training in techniques fortreatment in the event of electric shock;

I notices being posted in prominent places to advise on such treatment.

See Appendix 3

31

I Keep your arms straight and press down 4-5 ems,15 times at a quicker rate than once a second.

I Repeat mouth-to-mouth and continue the cycle atthe rate of two breaths to 15 compressions, with 4cycles per minute.

There should be no pause between the cycles. Twoinflations should take approximately 5 seconds and 15compressions should take approximately IO seconds.Continue until the casualty has been successfullyresuscitated, place in the recovery position if necessary,or until more expert help arrives. Treat other injuries asrequired.

To be competent at resuscitating effectively,it is advisable to receive emergency first aidtraining.

40

The Electricity at Work Regulations 1989

6 The Electricity at Work (EAW) Regulations 198g2 require those in control ofpart or all of an electrical system to ensure that the system is safe whenprovided, safe to use, and that it is maintained in a safe condition.

7 The EAW Regulations should not be confused with BS 7671 l6 (formallyknown as the IEE Wiring Regulations) which is a non-statutory code issued jointlyby the Institution of Electrical Engineers and the British Standards Institution. BS7671 l6 deals in detail with the safety of electrical installations.

The Provision and Use of Work Equipment Regulations 1992

8 The Provision and Use of Work Equipment Regulations 1 9923 place dutieson employers and the self-employed, to ensure the provision of safe and suitablework equipment, and to ensure its safe use. Selection of suitable work equipmentinvolves taking into account the risks that can arise from the place where it willbe used, and the purpose for which it will be used.

33

13

14

15

16

17

18

19

20

21

22

23

British Standards Institution BS 1363 13A piugs, socket-outlets and adaptors

British Standards Institution BS 7430 Code ofpractice for earthing 1991

The Electricity Association Recommendation for the connection ofembedded generating plant to the requirements of the electrjcalcompanies’ distribution system Engineering recommendation G 59-1 TheElectricity Association, 30 Millbank, London SW1 P 9RD

Institution of Electrical Engineers BS 7671 Requirements for electricalinstallations (IEE Winng Regulations) 1992 Institution of ElectricalEngineers, Hitchin Hertfordshire SG5 1 RS

British Standards Institution BS 4293 Specification for residual current-operated circuit-breakers 1983 (1993)

British Standards Institution BS 7071 Specification for portable residualcurrent devices 1992

British Standards Institution BS 7288 Specification for socket outletsincorporating residual current devices (SRCDs) 1990

HSE Maintaining portable and transportable electrical equipment HSG 107HSE Books 1994 ISBN 0 7176 0715 1

HSE Nectricity at work:safe working practices HSG85 HSE Books 1993ISBN 0 7176 0442 X

HSC Management of health and safety at work Management of Health andSafety at Work Regulations 1992 Approved Code of Practice HSE Books1992 ISBN 0 7176 0412 8

International Electrotechnical CommissionEffects of current passing through the human bodyPart 1: Genera/ aspects (I EC 479-I ) 1984Part 2: Special aspects (IEC 479-2) 1987

Further reading

HSE Protection against electric shock GS 27 HSE Books 1984iswk 0 I I 883583 I

British Standards Institution Code of practice for selection, installation andmaintenance of electrical apparatus for use in potentially explosive atmospheres(other than mining applications or explosive processing and manufacture)BS 5345 (8 parts)

42

6 A SELV system (sometimes called a safety extra low voltage system) limitsthe voltage available to a maximum of 50V. These systems are often used forlighting circuits or similar low power requirement situations, but the low voltagesmake the system less useful for use with power tools and more generalapplication.

7 The reduced low voltage system in most common use on UK building sitesfor general applications is that which is 1 IOV centre tapped to earth. In thissystem the source of the electrical supply is usually a double wound transformerwith an earthed screen between the primary and secondary windings of thetransformer. In addition, the star point or neutral of a 3 phase transformer isconnected to earth, and the centre point of a single phase or two pole winding isconnected to earth (See figures 1 and 2.) It is possible to use generators tosupply these systems and these should be configured to provide the samefeatures.

8 The phase-to-phase (for 3 phase supplies) and the pole-to-pole (for singlephase supplies) voltages on the secondary output do not exceed IlOV. Thecorresponding phase-to-earth and pole-to-earth voltages will then not exceed63.5V and 55V respectively at the transformer output terminals.

9 In this way, the system is able to supply 1 IOV to tools or equipment in useon the site, while technical investigation has shown that the maximum indirectcontact touch voltage to earth from one of these systems does not exceed 40V.This can be a steady state condition and it does not exceed the limits for electricshock protection set out in the protection curves for normal human bodyimpedance, as shown in IEC publications 479-l and 223.

10 These systems have been in widespread use for more than 50 years underthe rigours of construction and demolition sites and there is no record of any fatalaccidents which have occurred during that time. They achieve a high standard ofsafety compared to other systems of protection, and the need for maintenance isless.

35

Printed and published by the Health and Safety Executive

44

A P P E N D I X 3:E M E R G E N C Y P R O C E D U R E S

F O R A N ELEC’I’RIC S H O C KCASUAL’IY

Safety

The first priority for the rescuer is to avoid becoming acasualty and making the situation worse for otherrescuers. It is essential to make sure it is safe toapproach and to check if the casualty is still connectedto the electrical current in any way directly (to a faultymachine, apparatus or to a bare wire), or indirectly(lying on an electrically conductive surface).

Procedure

DO NOT touch the casualty with your unprotectedhands. Break the contact by switching off the current,removing the plug or wrenching the cable free.

If you are unable to isolate the casualty as alreadydescribed, you must stand on dry insulating materialsuch as a wooden box, a clean rubber or plastic mat, ora thick pile of dry newspapers. Then either:

I use a wooden or plasticimplement to free the casualtyfrom contact with the electricalsource; or

The unconscious casualty, who is breathing and has apulse, should be placed in the recovery position andmonitored until medical assistance arrives.

Mouth-to-mouth ventilation

If there is a pulse but the casualty is not breathing,begin mouth-to-mouth ventilation as follows:

I Kneel beside the casualty. While keeping thehead tilted backwards, open their mouth andpinch their nose (Step A)

I Open your mouth and take a deep breath. Sealtheir mouth with yours and breathe firmly into it.The casualty’s chest should rise.

I Remove your mouth and let the casualty’s chestfall (Step B). If the casualty’s chest does not riseand fall, check that:

H their head is tilted back sufficiently;n you have a firm seal around their

mouth;n their nostrils are closed completely;n their airway is not obstructed.

I Continue breathing into the casualty’s mouth at arate of 12-16 times a minute until they arebreathing by themselves. Then place the casualtyin the recovery position. If the casualty is notbreathing AND there is no pulse, Cardio-Pulmonary Resuscitation (CPR) must becarried out. CPR is mouth-to-mouth ventilationcombined with chest compression.

Cardio-Pulmonary Resuscitation (CPR)

I Give two breaths.

I Find the bottom of the breast bone.

I Two fingers’ breadth above this, place the heel ofone hand along the breast bone. Cover this handwith the other hand, interlocking your fingers.

39

R E F E R E N C E S rn~F U R T H E R R E A D I N G

1

2

3

4

5

6

7

8

9

10

11

12

HSE Managing construction for health and safety Construction (Designand Management) Regulations 1994 Approved Code of Practice L54 HSEBooks 1995 ISBN 0 7176 0792 5

HSE Memorandum of guidance on the Electricity at Work Regulations 1989HSR25 HSE Books 1989 ISBN 0 11 883963 2

HSE Work equipment Provision and Use of Work Equipment Regulations1992 Guidance on Regulations L22 HSE Books 1992 ISBN 0 7176 0414 4

British Standards Institution Arc welding power sources, equipment andaccessories BS 638

HSE Electrical safety in arc welding HSGl18 HSE Books 1994lSBNO717607046

Health and Safety at Work etc Act 1974 Chapter 37 HMSOISBN 0 10 543774 3

HSE Avoidance of danger from overhead electrical lines GS 6 HSE Books1991 ISBN 0 11 885668 5

HSE Avoiding danger from underground services HSG47 HSE Books1989 ISBN 0 7176 0435 7

British Standards Institution Code of practice for distribution of electricity onconstruction and building sites BS 7375 1991

Bntrsh Standards Institution Specification for distribution assemblies foreiectricity supplies for construction and building sites BS 4363 1991

British Standards Institution BS EN 60439-4 Particular requirements forassemblies for construction sites (ACS) 1991

British Standards Institution (This standard is dual numbered)

BS 4343 Plugs, socket-outlets and couplers for industrial purposes 1992BS EN 60309-2 Dimensional interchangeability requirements for pin and contact-tube accessories of harmonised configurations 1992

41

Building Employers Confederation Construction safety manual Section 10Electricity Building Employers Confederation, 82 New Cavendish Street, LondonWIM 8AD

HSE Health and safety for small construction sites HSG 130 HSE Books 1995ISBN 0 7176 0806 9

The future availability and accuracy of the references listed in this publicationcannot be guaranteed.

HSE priced and free publications are available by mail order from:HSE BooksPO Box 1999SudburySuffolk COI 0 6FS

Tel: 01787 881165Fax: 01787 313995

HSE priced publications are also available from good booksellers

For other enquiries ring HSE’s InfoLine Tel: 0541 545500 or write to HSE’sInformation Centre, Broad Lane, Sheffield S3 7HQ.

HSE home page on the World Wide Web:http://www.open.gov.uk/hse/hsehome.htm

British Standards are available from:

British Standards Institution389 Chiswick High RoadLondon W4 9AL

Tel: 0181 966 7000Fax: 0181 996 7001

43

HSEBOOKS

hIAIL ORDERHSE priced and freepublications areavailable horn:HSE BooksPO Box 1999SudburySuffolk COI0 6FSTel: 01787 881165Fax: 01787 313995

RETAILHSE priced publicationsare available fromgood booksellers

HEALTH AND SAFETY ENQUIRIESHSE InfoLineTel: 054 1 545500or write to:HSE Information CentreBroad LaneSheffield S3 7IIQ

HSE home page on the World Wide Web:http://www.open.gov.uk/hse#hsehome.htm