SASCO NFPA 70E Training

SASCO NFPA 70E Training

SASCO NFPA 70E Training

•NFPA 70E—Standard for Electrical Safety in the Workplace–Title: Standard for Electrical Safety for Employee Workplaces

–Began 1976 by NFPA. Guidance for OSHA

Electrical Hazards Addressed in NFPA 70E•Shock

•Arc Flash & Arc Blast•Fire Ignition

The Effects of Current on the Body

Burns

Two Types of Burns from Shock

• Surface Burns– Entrance and

exit of a electrical currents through the body

– Can be a very small amount of current

– 1st to 3rd degree

Two Types of Burns from Shock

• Internal Tissue burns– From current

running through the organs of the body

– Currents in excess of 1.5 amps

– 3rd degree burns– Damage to

internal organs– Often fatal

One Type of Burn From Arc Flash

• Surface Burns– From exposure to arc flash– Can cause more surface burns if the

initial arc ignites other material, such as clothing

– 1st degree to third degree burns

– Has caused deathHas caused death

Probability of Survival

The probability of surviving burns decreases with age:

How to Prevent Shock?1. Place circuits in an electrically safe

working condition by locking out and tagging out all energy sources

– NFPA 70E-2004: Chapter 1, Section 120.2 (D)

2. Verify that no electrical energy is present

– NFPA 70E-2004: Chapter 1, Section 120.2 (D)

Exposure to DangerExposure to Danger• The National Electric Code (NEC) was

designed to protect individuals from shock hazards under normal conditions.

• It is not designed to protect employees under abnormal conditions.

• We need additional policies to protect us under abnormal conditions.

This is normal somewhere in the world

Notes From Practical Guide to Arc Flash Hazards,

By Chet Davis, P.E.; Conrad St. Pierre; David Castor, P.E.; Robert Luo, PhD; and Satish Shrestha

• Electrical arcs produce the highest temperatures on earth—up to 35,000ºF. That’s 4 times the temperature of the sun.

• The intense heat from arc causes the sudden expansion of air that results in a blast with very strong air pressure. (Lightning is a natural arc.)

• All known materials vaporize at this temperature.– Copper expands 67,000 times; Water expands 1670 times.

What NFPA 70E is designed to take into account:

Arc Flash Characteristics• Arcs in enclosures, such as Motor Control

Centers (MCCs) or switchgear, magnify blast and energy transmitted as the blast is forced to the open side of the enclosure.

• Arcs spray droplets of molten metal at velocity and pressure. Shrapnel can penetrate the body

• Blast pressure waves have thrown workers across rooms and knocked them off of ladders. Pressure to the chest can exceed 2,000 lbs/sq. ft.

Notes From Practical Guide to Arc Flash Hazards

Arc Flash Characteristics• Clothing can be ignited from several feet away.

Clothed areas can burn more severely than exposed skin.

• Hearing loss from sound blast. The sound can have a magnitude as high as 140 dB at distance of 2 feet from the arc.

• Energy released is a function of:– System voltage– Fault current magnitude– Fault duration

Notes From Practical Guide to Arc Flash Hazards

How to Protect Against Shock and Arc Flash/Blast?

• NFPA 70E-2004– Chapter 1, Section 130

1. Justification for Live Work2. Work Permits Secured—If Applicable3. Approach Boundaries Established

• Shock Protection• Limited Boundary

Note: De-energization is covered in Section 120

Note: De-energization is covered in Section 120

OSHA 1910.333 (a) (1) and NFPA 70E 130.1

• Qualified electrical workers shall not be asked to work on equipment that is “live” except for two demonstrable reasons:

1. Deenergizing introduces additional or increased hazardsExample: Cutting ventilation to a

hazardous location

OR:

2. Infeasible because of equipment design or operational limitsExample: Volt testing for diagnostics

Energized Electrical Work Permit

• NFPA 130.1 (A) (1):– “If live parts are not placed in an

electrically safe work condition (i.e., for the reasons of increased or additional hazards of infeasibility per 130.1), work to be performed shall be considered energized electrical work and shall be performed by written permit only.”

Exemptions to Work Permit• “Work performed on or near live

parts by qualified persons related to tasks such as testing, troubleshooting, voltage measuring, etc., shall be permitted without energized electrical work permit, provided appropriate safe work practices and person protective equipment in accordance with Chapter 1 are provided and used.”

Approach Boundaries to Live Parts

Picture From Practical Guide to Arc Flash Hazards

Approach Boundaries

• Flash Protection BoundaryFlash Protection Boundary– Linear distance at which no more than 2nd

degree burns possible from potential arc flash (typically 4 feet).

• See table 130.2 (c)

• Limited Approach Boundary– Entered only by qualified persons or unqualified

persons who have been advised and are escorted by a qualified person

• Restricted Approach Boundary – Entered only by qualified persons required to use

shock protection techniques and P.P.E.

• Prohibited Approach Boundary– Enter only by qualified persons requiring same

protection as if in direct contact with live part

NFPA 70E-2004 Chapter 1, Sect. 130.2

Shock Hazard Analysis• How to Comply with NFPA

70E– 3. Determine Personal

Protective Equipmenta. Determine Risk Category from

Table 130.7 (C) (9) (a) on NFPA 70E-2004

b. Determine Specific PPE & Clothing from Table 130.7 (C) (10) of NFPA 70E-2004

Shock Hazard Analysis

Determining Risk Category from Table 130.7 (C) (9) (a) on NFPA 70E-2004

Determining PPE from Table 130.7 (C) (10) on NFPA 70E-2004

Flash Hazard Analysis Example

Task: An electrician is to remove the covers to measure the voltage on a panel board operating at 480 V.

Solution: Table 130.7 (C) (9): Hazard/Risk Category=2*(V-Rated Gloves & V-Rated Tools Required)

Table 130.7 (C) (10) Specifies the following:• Untreated Natural Fiber T-Shirt & Undergarments• FR (8 cal/cm2) Long Sleeve Shirt and Pants• Hard Hat• Safety Glasses or Safety Goggles• Arc-Rated Face Shield w/ Flash Hood • Hearing Protection• Leather Gloves• Leather Work Shoes

No Fabric Softener or Bleach

Shortcut (2) to ppe arc flash portion.wmv.lnk

Common PPE Terms• Incident Energy: Measurement of thermal energy at

a specified distance for the arc (normally 18”). Energy is typically measured in cal/cm2.

• Arc Thermal Performance Exposure Value (ATPV): The incident energy level (in cal/cm2) that would cause the onset of a second-degree burn.

• V-rated: Tools and gloves tested for the line-to-line voltage at the area where the work is to be performed.

• Flame-Resistant or Flame-Retardant: A term referring to fabric and its ability to limit severity of burning.

• Break-open Threshold Energy (EBT): The highest incident energy level which did not cause flame resistant (FR) fabric break-open and does not exceed second-degree burn criteria.

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Determining PPE by using NFPA 70ENFPA 70E Table 130.7(c)(9)(a)

1. Determine common work task from table that matches work to be performed.

2. Identify Hazard/Risk Category of task (0-4).3. Refer to NFPA Table 130.7(c)(10):

Protective Clothing and Personal Protective Equipment Matrix.

4. Read all applicable “Notes” that may apply.

Note: Any task not covered in tables or exceed assumptions are required to have a Flash Hazard Analysis performed in accordance with NFPA 70E 130.3

Review:

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And now you know the rest of the story…

Elimination/Substitution & Engineering Controls

•Substitute for hazardous materials/reduce energy or speed

•Machine guarding/sound enclosures/circuit breakers

National Safety Council Hierarchy of ControlsNational Safety Council Hierarchy of Controls

Warnings

•Signs/placards/alarms/back-up beepers/labels

Training/Procedures

Administrative Controls•Lockout-Tagout/Job Hazard Analysis

•Rotation of workers

P.P.E.

Other Protective Equipment: Insulated Tools

• 1. • Insulated tools and equipment must be rated for the voltages on which they are used

• Insulated tools—designed and constructed for the environment and manner in which they are used.

Alerting Techniques

• 1. • Physical barricades• Signage• Attendants

– “If barricades and signage fail to provide sufficient warning and protection from electrical hazards, an attendant shall be stationed to warn and protect employees.”

2002 NEC

•§ 110.16 Requires Arc Flash Labels

Response to an Electrical Accident

•Personnel who are trained to perform First-Aid/CPR should be identified and available when work near or on energized part is being performed

The first step must be to

TURN OFF THE POWER

Response to an Electrical Accident

Steps to Take if an Electrical Incident OccursIf power cannot be turned off, break victim’s contact with electricity

Steps to Take if an Electrical Incident Occurs

• Remove the immediate hazard: Turn off the power

• Remember speed is essential

• Extinguish flames• Call for help (911)• Begin First-Aid &

CPR

• First Aid– Cool the burn with

water– DO NOT attempt to

remove burnt clothing– Elevate burned limbs– Handle the victim with

care– Treat for shock

• Maintain body temperature

• Do not give anything by mouth

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Any Questions?