Electrical Safety for Construction. Electrical regulations v Subpart K of 29 CFR 1926 1a.

Electrical Safety for Electrical Safety for ConstructionConstruction

Electrical regulationsElectrical regulations

Subpart K of 29 CFR 1926Subpart K of 29 CFR 1926

1a


Part I - Safety requirements for Part I - Safety requirements for installing/using equipmentinstalling/using equipment• approval of electrical componentsapproval of electrical components• examination, installation, use of examination, installation, use of

electrical equipmentelectrical equipment• guarding of electrical equipmentguarding of electrical equipment• overcurrent protectionovercurrent protection• grounding of equipmentgrounding of equipment

1b


Part II - Safety-related work Part II - Safety-related work practicespractices• protection of employeesprotection of employees• passageways and open spacespassageways and open spaces• lockout/tagging of circuitslockout/tagging of circuits

1c


Part III - Safety-related Part III - Safety-related maintenance and environmental maintenance and environmental considerationsconsiderations• protection of wiring componentsprotection of wiring components• environmental deterioration of environmental deterioration of

equipmentequipment

1d


Part IV - Safety requirements for Part IV - Safety requirements for special equipmentspecial equipment• batteries and battery chargingbatteries and battery charging• PPEPPE• emergency eyewash stationsemergency eyewash stations

1e

How electricity worksHow electricity works

Current flows from a generating Current flows from a generating source through conductors, to a source through conductors, to a loadload

Complete Complete circuits are circuits are neededneeded

2a

How electricity worksHow electricity works

Normal route is through Normal route is through conductorsconductors

Shock occurs Shock occurs when the body when the body becomes a becomes a part of the part of the electrical electrical circuitcircuit

2b

I = Current (amperes)I = Current (amperes)

E = Voltage (volts)E = Voltage (volts)

R = Resistance (ohms) R = Resistance (ohms)

EI R

Ohm’s LawOhm’s Law

Body AreaBody Area OHMSOHMSDry SkinDry Skin 600,000 600,000

Wet SkinWet Skin 1,000 1,000

Internal OrgansInternal Organs 400-600400-600

Ear to EarEar to Ear 100 100

Human ResistanceHuman Resistance

50 Volts50 Volts

1,000 OHM1,000 OHM = .05 amps (50 mA)= .05 amps (50 mA)

50 Volts50 Volts

100 OHM100 OHM = .5 amps (500 mA)= .5 amps (500 mA)

Fatalities at 50 VoltsFatalities at 50 Volts

Electric shockElectric shock

Occurs when current enters the body Occurs when current enters the body at one point and exits at anotherat one point and exits at another

Shock occurs when you touch:Shock occurs when you touch:• both wires of an electric circuit;both wires of an electric circuit;• one wire of an energized circuit and one wire of an energized circuit and

ground; orground; or• a metallic part that is “hot”a metallic part that is “hot”

3a


Severity of shock depends on the:Severity of shock depends on the:• amount of currentamount of current• path of the currentpath of the current• amount of time amount of time

exposedexposed

3b


Effects range from a tingle, to Effects range from a tingle, to cardiac arrest, severe cardiac arrest, severe burns, and probable burns, and probable deathdeath

Typical household Typical household current of 15 amps current of 15 amps can cause deathcan cause death

3c

Electricity’s Physiological Electricity’s Physiological EffectEffect

00.001 amps00.001 amps 00.015 amps00.015 amps 00.020 amps00.020 amps 00.10000.100 01.20001.200 15.00015.000

Barely feltBarely felt ““let go” thresholdlet go” threshold Muscular paralysisMuscular paralysis Ventricular Ventricular

fibrillationfibrillation 100 Watt light bulb100 Watt light bulb Common household Common household

fusefuse

1-8 mA = shock, not painful1-8 mA = shock, not painful

8-15 mA = Pain8-15 mA = Pain

15-20 mA = Muscle contraction15-20 mA = Muscle contraction

20-100 mA = Severe pain & paralysis 20-100 mA = Severe pain & paralysis of breathing muscles of breathing muscles

100-1000 mA = Ventricular fibrillation100-1000 mA = Ventricular fibrillation

(Usually cause death)(Usually cause death)

> 1,000 mA = Heart stops> 1,000 mA = Heart stops

Effects of CurrentEffects of Current

GroundingGrounding

Protects you from electrical shockProtects you from electrical shock

Safeguards Safeguards against fireagainst fire

Protects electrical equipment from Protects electrical equipment from damagedamage

4a

GroundingGrounding

Two types of grounding include:Two types of grounding include:• Service or system Service or system

groundground• Equipment groundEquipment ground

4b

Circuit protective devicesCircuit protective devices

At construction sites, the most At construction sites, the most common electrical hazard is the common electrical hazard is the ground fault electrical shockground fault electrical shock

OSHA requires either:OSHA requires either:• Ground fault circuit interrupters Ground fault circuit interrupters

(GFCIs); or(GFCIs); or• Assured Grounding Conductor ProgramAssured Grounding Conductor Program

5a

Circuit protective devicesCircuit protective devices

Circuit protective devices include:Circuit protective devices include:• fuses and circuit breakers - protect fuses and circuit breakers - protect

conductors and equipmentconductors and equipment• GFCIs - limit or shut off current flowGFCIs - limit or shut off current flow

5b

Ground fault circuit Ground fault circuit interruptersinterrupters

A fast-acting circuit breaker that A fast-acting circuit breaker that senses small imbalances in the senses small imbalances in the circuit caused by current leakage circuit caused by current leakage to groundto ground

6a

PLUG

COIL

LOAD

HOT NEUTRAL

1 AMP

1 AMP

1 AMP

PLUG

COIL

LOADHOT NEUTRAL

1000 mA

995 mA

5 mA

GROUND

1000 mA

PLUG

COIL

LOAD

HOT NEUTRAL

1000 mA

1 AMP

5 mA

GROUND

995 mA

PolarityPolarity

Assured Equipment Assured Equipment Grounding Conductor Grounding Conductor programprogram

If GFCIs are not used, employers If GFCIs are not used, employers must have a scheduled and must have a scheduled and recorded Assured Equipment recorded Assured Equipment Grounding Conductor programGrounding Conductor program

7a

The AEGC program is an inspection The AEGC program is an inspection program covering:program covering:• all cord setsall cord sets• receptacles that are not part of a receptacles that are not part of a

permanent wiring structurepermanent wiring structure• equipment connected by cord and equipment connected by cord and

plugplug

7b


Equipment must be visually Equipment must be visually inspected for damage/defects inspected for damage/defects before each day’s usebefore each day’s use

7c


Tests must be performed:Tests must be performed:• before the first use of new equipmentbefore the first use of new equipment• after suspected damage to equipmentafter suspected damage to equipment• at three month intervalsat three month intervals

– continuity testcontinuity test– grounding conductor testgrounding conductor test

7d


Lockout/TagoutLockout/Tagout

Electrical equipment deactivated for Electrical equipment deactivated for repair must be locked out and repair must be locked out and tagged at the point where it can be tagged at the point where it can be energizedenergized

Protects maintenance workersProtects maintenance workers

Warns others that work is being Warns others that work is being performedperformed

8a


Only the person who locked/tagged Only the person who locked/tagged the equipment can turn it back onthe equipment can turn it back on

Before equipment is energized, a Before equipment is energized, a qualified person must conduct qualified person must conduct tests and visual inspectionstests and visual inspections

8b


Each lock/tag must be removed by Each lock/tag must be removed by the person who applied itthe person who applied it

8c


If the employee is absent, the If the employee is absent, the lock/tag can be removed by a lock/tag can be removed by a qualified person if:qualified person if:• the employee who applied the lock the employee who applied the lock

has left the premiseshas left the premises• it is visually determined that all it is visually determined that all

employees are clear of the employees are clear of the circuits/equipmentcircuits/equipment

8d

Guarding requirementsGuarding requirements

Any live parts of electrical Any live parts of electrical equipment operating at 50 volts or equipment operating at 50 volts or more must be guarded to avoid more must be guarded to avoid accidental contactaccidental contact

9a

Guarding requirementsGuarding requirements

Entrances to areas with live Entrances to areas with live electrical parts must be marked electrical parts must be marked with warning signswith warning signs

Signs should Signs should forbid entrance forbid entrance except by except by qualified personsqualified persons

9b

InsulationInsulation

Check equipment daily for Check equipment daily for insulation breakdowninsulation breakdown

Check for:Check for:• exposed wiresexposed wires• broken wiresbroken wires• scuffed insulation on extension cordsscuffed insulation on extension cords

10a

InsulationInsulation

Use non-conducting mats, shields, Use non-conducting mats, shields, or barriers when necessaryor barriers when necessary

Use non-Use non-conducting conducting coatings on coatings on hand toolshand tools

10b

Personal protective Personal protective equipmentequipment

Employers must provide electrical Employers must provide electrical protective equipment to protective equipment to employees employees who work near who work near electrical electrical hazardshazards

11a

Personal protective Personal protective equipmentequipment

Use appropriate equipment for the Use appropriate equipment for the hazards, including:hazards, including:• helmetshelmets• eye and face eye and face

protectionprotection• gloves and gloves and

sleevessleeves• apronsaprons• protective footwearprotective footwear

11b

Electrical Safety for Construction. Electrical regulations v Subpart K of 29 CFR 1926 1a.

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