Electrical

ElectricalElectrical

These handouts and documents with attachments are not final, complete, or definitive instruments. This information is for These handouts and documents with attachments are not final, complete, or definitive instruments. This information is for guidance purposes only. You should independently verify and satisfy yourself as to its accuracy. The AHBSIF does not guidance purposes only. You should independently verify and satisfy yourself as to its accuracy. The AHBSIF does not

assume any liability for damages arising from the use of this information or exhibits and attachments thereto and renders no assume any liability for damages arising from the use of this information or exhibits and attachments thereto and renders no opinion that any of the terms, conditions, and/or cited federal standards in this document and the exhibits and attachments opinion that any of the terms, conditions, and/or cited federal standards in this document and the exhibits and attachments

should be explicitly followed by the fund member. Seek specific guidance from the appropriate regulator (OSHA) or should be explicitly followed by the fund member. Seek specific guidance from the appropriate regulator (OSHA) or professional advisor.professional advisor.

Serious ExposureSerious Exposure

Electrocution is one of Electrocution is one of the top four causes of the top four causes of construction fatalitiesconstruction fatalities

Nearly half of those Nearly half of those fatalities were the result fatalities were the result of contact with overhead of contact with overhead power lines power lines

OSHA is making an OSHA is making an effort to focus more effort to focus more attention to these attention to these exposuresexposures

Applicable StandardsApplicable Standards

Electrical standards are among the Electrical standards are among the most frequently cited by OSHAmost frequently cited by OSHA No Lock Out/Tag OutNo Lock Out/Tag Out Improper Wiring MethodsImproper Wiring Methods Inadequate Components and EquipmentInadequate Components and Equipment

OSHA references the following for OSHA references the following for guidelinesguidelines Electric Safety Requirements for Electric Safety Requirements for

Employee Workplaces and codes (NFPA Employee Workplaces and codes (NFPA 70E)70E)

Basic TerminologyBasic Terminology

AmpsAmps – The amount of – The amount of electricity flowingelectricity flowing

VoltsVolts – The force at which the – The force at which the power flowspower flows

OhmsOhms – A unit of electrical – A unit of electrical resistanceresistance

WattsWatts – A unit of electrical – A unit of electrical powerpower

Physical EffectsPhysical Effects Amps are the true measure Amps are the true measure

of current absorbed, not voltsof current absorbed, not volts We are good conductors, the We are good conductors, the

human body is 70% waterhuman body is 70% water Involuntary muscle Involuntary muscle

contraction is the reason we contraction is the reason we are affectedare affected Can’t let go of energized objectCan’t let go of energized object Breathing is impairedBreathing is impaired Heart rhythm is disruptedHeart rhythm is disrupted

Physical EffectsPhysical Effects

1 1 mAmA

16 mA16 mA

20 mA20 mA

100 mA100 mA

2 amps2 amps

15 to 20 amps15 to 20 amps

Barely perceptibleBarely perceptible

Max current an average man can grasp Max current an average man can grasp and let goand let go

Paralysis of respiratory musclesParalysis of respiratory muscles

Ventricular fibrillation thresholdVentricular fibrillation threshold

Cardiac standstill and internal organ Cardiac standstill and internal organ damagedamage

Current required to trip common Current required to trip common household breakerhousehold breaker

Influencing Factors of a Influencing Factors of a ShockShock

Circumstances that affect the Circumstances that affect the outcome of an electric outcome of an electric shockshock;;

Circuit voltageCircuit voltage The bodies external (skin) The bodies external (skin)

and internal resistanceand internal resistance Total current flowing Total current flowing

through the bodythrough the body Current pathCurrent path The duration of the shockThe duration of the shock

Arc FlashArc Flash The result of a rapid release of The result of a rapid release of

energy due to an arcing fault, air is energy due to an arcing fault, air is the conductor.the conductor.

Arc faults are generally limited to Arc faults are generally limited to systems where the voltage is in systems where the voltage is in excess of 120 volts.excess of 120 volts.

Massive energy is discharged, Massive energy is discharged, vaporizing the copper and causing vaporizing the copper and causing an explosion.an explosion.

Arcs can produce temperatures up Arcs can produce temperatures up to 35,000° F.to 35,000° F.

Flash hazards can produce Flash hazards can produce pressure waves, concentrated pressure waves, concentrated sound blasts, and release deadly sound blasts, and release deadly shrapnel.shrapnel.

Arc FlashArc Flash

Arc flash and blast hazards were not Arc flash and blast hazards were not formally studied until the early 90’sformally studied until the early 90’s

Generally occur less frequently than Generally occur less frequently than electric shockelectric shock

NFPA 70E provides directives on NFPA 70E provides directives on reducing the occurrence and effects reducing the occurrence and effects of arc flashof arc flash

NFPA 70E – Flash Protection NFPA 70E – Flash Protection GuidelinesGuidelines

Compliance of NFPA 70E, Arc Flash Compliance of NFPA 70E, Arc Flash Protection requires the following:Protection requires the following: Justification for live workJustification for live work Work Permits when applicableWork Permits when applicable Approach BoundariesApproach Boundaries

Approach BoundariesApproach BoundariesLimited Approach BoundaryLimited Approach Boundary

Entered only by a Qualified Entered only by a Qualified Person or unqualified person Person or unqualified person escorted by QPescorted by QP

Restricted Approach BoundaryRestricted Approach Boundary Entered only by a Qualified Entered only by a Qualified

Person required to use shock Person required to use shock protection techniques and PPEprotection techniques and PPE

Prohibited Approach BoundaryProhibited Approach Boundary Entered only by a Qualified Entered only by a Qualified

Person requiring same Person requiring same protection as if in direct contact protection as if in direct contact with live partwith live part

Electric

Panel

Front

Flash Protection BoundaryFlash Protection Boundary

The Flash Protection The Flash Protection Boundary is the linear Boundary is the linear distance to prevent any distance to prevent any more than 2more than 2ndnd degree degree burns from a potential burns from a potential arc flasharc flash

Distance is usually four Distance is usually four feetfeet

Distances for all shock Distances for all shock protection boundaries protection boundaries can referenced in Table can referenced in Table 130.2(C) of NFPA 70E130.2(C) of NFPA 70E

Electric

Panel

Front

What kind of PPE is What kind of PPE is necessary?necessary?

The level of personal protective The level of personal protective equipment necessary for the equipment necessary for the exposure can be determined one of exposure can be determined one of two ways:two ways:

Shock Hazard AnalysisShock Hazard Analysis

- OR -- OR - Flash Hazard AnalysisFlash Hazard Analysis

Shock Hazard AnalysisShock Hazard Analysis

Must determine the following:Must determine the following: The operating voltage of the systemThe operating voltage of the system Shock protection boundariesShock protection boundaries Required personal protective equipment Required personal protective equipment

[ reference Tables 130.7(C)(9)(a) and 130.7(C)[ reference Tables 130.7(C)(9)(a) and 130.7(C)(10) NFPA 70E ](10) NFPA 70E ]

Flash Hazard AnalysisFlash Hazard Analysis

Must determine the following:Must determine the following: The flash protection boundaryThe flash protection boundary The incident energy exposure levelThe incident energy exposure level Protective clothing and PPEProtective clothing and PPE

Flash Hazard AnalysisFlash Hazard Analysis

The flash protection boundaryThe flash protection boundaryUse the flash protection boundary formula Use the flash protection boundary formula OROR default 130.3(A)default 130.3(A)

The incident energy exposure levelThe incident energy exposure leveldistance between workers face and chest from distance between workers face and chest from the arc source the arc source OROR 130.7(C)(9) and 130.7(C) 130.7(C)(9) and 130.7(C)(10)(10)

Protective clothing and PPEProtective clothing and PPEOnce incident energy is determined, safety Once incident energy is determined, safety equipment has to have a rating greater than or equipment has to have a rating greater than or equal to the incident energy availableequal to the incident energy available

Personal Protective Clothing, Personal Protective Clothing, NFPA 70ENFPA 70E

CategoryCategory Cal/cmCal/cm22 ClothingClothing

00 1.21.2 Untreated CottonUntreated Cotton

11 55 Flame retardant (FR) shirt and Flame retardant (FR) shirt and FR pantsFR pants

22 88 Cotton underwear FR shirt and Cotton underwear FR shirt and FR pants FR pants

33 2525 Cotton underwear FR shirt, FR Cotton underwear FR shirt, FR pants and FR coveralls pants and FR coveralls

44 4040 Cotton underwear FR shirt, FR Cotton underwear FR shirt, FR pants and double layer switching pants and double layer switching coat and pants coat and pants

Employer ResponsibilitiesEmployer Responsibilities

Equipment must be:Equipment must be: Free from recognized hazards Free from recognized hazards Suitable and identified through Suitable and identified through

listing, labeling, or certification of listing, labeling, or certification of purpose.purpose.

Designed with adequate Designed with adequate mechanical strength and durability mechanical strength and durability

Other items for considerationOther items for consideration Electrical insulationElectrical insulation Heating effects /conditions Heating effects /conditions

of useof use Arcing effectsArcing effects Use classificationsUse classifications

GuardingGuarding Live parts of electrical equipment operating at 50 Live parts of electrical equipment operating at 50

volts or more must be guarded against accidental volts or more must be guarded against accidental contact.contact.

Means of acceptable guarding include:Means of acceptable guarding include: Isolation in a cabinet, room, or vault accessible only Isolation in a cabinet, room, or vault accessible only

by qualified personsby qualified persons Use of partitions or screens to exclude unqualified Use of partitions or screens to exclude unqualified

personspersons Elevation of eight feet or more above the floorElevation of eight feet or more above the floor

Electric installations over 600 require special Electric installations over 600 require special protectionprotection metal-enclosedmetal-enclosed VaultVault controlled by lockcontrolled by lock

Lock Out / Tag OutLock Out / Tag Out

LOTO written LOTO written program program ComponentsComponents

Documented Documented energy control energy control proceduresprocedures

Employee Training Employee Training programprogram

Inspection programInspection program

Lock Out / Tag OutLock Out / Tag Out Purpose is to draw Purpose is to draw

attention to and disable attention to and disable a live energy source a live energy source during service and repair during service and repair work.work.

Lock Out physically Lock Out physically disables the energy disables the energy source, Tag Out provides source, Tag Out provides a warning onlya warning only

OnlyOnly the employee who the employee who placed the lock or tag placed the lock or tag may remove it!may remove it!

Safe Power ShutdownSafe Power Shutdown- 5 Steps -- 5 Steps -

Preparation and NotificationPreparation and Notification– – Understanding energy source and Understanding energy source and alerting all affected employeesalerting all affected employees

ShutdownShutdown – De-energizing procedure – De-energizing procedure IsolationIsolation – Properly locking all power – Properly locking all power

sourcessources Lock & Tag ApplicationLock & Tag Application

Color coding for different tradesColor coding for different trades Employee assigned locksEmployee assigned locks Photo tags, helps locate employee, Photo tags, helps locate employee,

makes associationmakes association ControlControl and Verificationand Verification– Control – Control

stored and residual energy with locks in stored and residual energy with locks in placeplace

Re-energizingRe-energizing- 3 Steps -- 3 Steps -

InspectionInspection – checking – checking the work area and the work area and surrounding surrounding machinery and for machinery and for employeesemployees

NotificationNotification – Make – Make notice to all affected notice to all affected employees as to what employees as to what will be re-energizedwill be re-energized

Removal of Tags Removal of Tags and Locksand Locks

Tags and LocksTags and Locks

Tags and Locks must be:Tags and Locks must be: DurableDurable – resist conditions of – resist conditions of

environmentenvironment StandardizedStandardized – color code and format – color code and format Substantial Substantial – strong enough to minimize – strong enough to minimize

false removalfalse removal IdentifiableIdentifiable – clear message, know who – clear message, know who

it is protectingit is protecting

Extension CordsExtension Cords Cords with missing ground prongs, insulation breeches, crimping Cords with missing ground prongs, insulation breeches, crimping

or crushing, must be removed from service.or crushing, must be removed from service. Splicing is prohibited, but new connectors are acceptableSplicing is prohibited, but new connectors are acceptable When unplugging, pull the plug, never tug on the cordWhen unplugging, pull the plug, never tug on the cord If a cord must cross a vehicle pathway it must be protectedIf a cord must cross a vehicle pathway it must be protected OSHA considers an extension cord temporary power, no matter OSHA considers an extension cord temporary power, no matter

the power source!the power source!

Service RatingsService RatingsHard ServiceHard Service (types S, ST, SO, STO)(types S, ST, SO, STO)

Junior Hard ServiceJunior Hard Service (types SJ, SJO, SJT, (types SJ, SJO, SJT, SJTO)SJTO)

Home use, small applianceHome use, small appliance (type SP)(type SP)

Ground Fault Circuit Ground Fault Circuit InterruptersInterrupters

Ground Fault Circuit Ground Fault Circuit Interrupters (GFCI’s) sense Interrupters (GFCI’s) sense changes in current (5 changes in current (5 milliamps) and stop energy milliamps) and stop energy flow.flow.

Devices stop current in 1/40 Devices stop current in 1/40 of a secondof a second

Never bypass any protective Never bypass any protective system or device designed system or device designed to keep you from contact to keep you from contact with electrical current.with electrical current.

All temporary power sources All temporary power sources must have GFCI protection must have GFCI protection either at main box, either at main box, extension cord, or tool.extension cord, or tool.

Portable GeneratorsPortable Generators Never use a generator Never use a generator

indoors or in an attached indoors or in an attached garage.garage.

Use extension cords with Use extension cords with adequate duty ratings. adequate duty ratings.

To prevent electrical To prevent electrical shock, make sure your shock, make sure your generator is properly generator is properly grounded.grounded.

Do not store fuel indoors or Do not store fuel indoors or try to refuel a generator try to refuel a generator while it's running. while it's running.

Turn off all equipment Turn off all equipment powered by the generator powered by the generator before shutting it downbefore shutting it down..

Other ConsiderationsOther Considerations

Environmental Deterioration of Environmental Deterioration of EquipmentEquipment - Unless specified for use in - Unless specified for use in such an environment, no conductors or such an environment, no conductors or equipment should be exposed to;equipment should be exposed to; Damp or wet locationsDamp or wet locations Gases, fumes, vapors, liquids, or Gases, fumes, vapors, liquids, or

other deteriorating agentsother deteriorating agents Excessive Temperatures Excessive Temperatures

Safe Work PracticesSafe Work Practices Always check the location of Always check the location of

overhead power lines (most overhead power lines (most common source of electrocution)common source of electrocution)

Stay away from energized power Stay away from energized power circuitscircuits

Locate all utilities prior to digging Locate all utilities prior to digging or jack hammeringor jack hammering

Protect electrical equipment in Protect electrical equipment in passageways from contactpassageways from contact

Keep walking and working Keep walking and working surfaces free of electrical cords surfaces free of electrical cords as much as possibleas much as possible

Always de-energize equipment Always de-energize equipment before repair or service workbefore repair or service work

Electrical ChecklistElectrical ChecklistExtension cords:Extension cords:

- No crimping or crushing- No crimping or crushing

- No missing insulation- No missing insulation

- No signs of stress at plug- No signs of stress at plug

All extension cords out of All extension cords out of high traffic areas:high traffic areas:

- Road ways (protective cover)- Road ways (protective cover)

- Driveways- Driveways

- Hallway, entrance, stairwell- Hallway, entrance, stairwell

Lock Out / Tag Out plan for all Lock Out / Tag Out plan for all maintenance operationsmaintenance operations

Equipment rated for duty Equipment rated for duty and environmentand environment

Proper PPE when necessaryProper PPE when necessary GFCI protection at box, cord, GFCI protection at box, cord, or toolor tool

Awareness of all overhead Awareness of all overhead power linespower lines

All tools double insulatedAll tools double insulated

Pre-job identification of all Pre-job identification of all underground utilitiesunderground utilities

Generators must have earth Generators must have earth groundground