Electrical Safety for Construction

Electrical regulations v Subpart K of 29 CFR a

Electrical regulations v Part I - Safety requirements for installing/using equipment approval of electrical componentsapproval of electrical components examination, installation, use of electrical equipmentexamination, installation, use of electrical equipment guarding of electrical equipmentguarding of electrical equipment overcurrent protectionovercurrent protection grounding of equipmentgrounding of equipment 1b

Electrical regulations v Part II - Safety-related work practices protection of employeesprotection of employees passageways and open spacespassageways and open spaces lockout/tagging of circuitslockout/tagging of circuits 1c

Electrical regulations v Part III - Safety-related maintenance and environmental considerations protection of wiring componentsprotection of wiring components environmental deterioration of equipmentenvironmental deterioration of equipment 1d

Electrical regulations v Part IV - Safety requirements for special equipment batteries and battery chargingbatteries and battery charging PPEPPE emergency eyewash stationsemergency eyewash stations 1e

How electricity works v Current flows from a generating source through conductors, to a load v Complete circuits are needed 2a

How electricity works v Normal route is through conductors v Shock occurs when the body becomes a part of the electrical circuit 2b

I = Current (amperes) I = Current (amperes) E = Voltage (volts) E = Voltage (volts) R = Resistance (ohms) R = Resistance (ohms) E IR Ohm’s Law

Body Area OHMS Dry Skin600,000 Wet Skin 1,000 Internal Organs Ear to Ear 100 Human Resistance

50 Volts 50 Volts 1,000 OHM=.05 amps (50 mA) 50 Volts 50 Volts 100 OHM=.5 amps (500 mA) 100 OHM=.5 amps (500 mA) Fatalities at 50 Volts

Electric shock v Occurs when current enters the body at one point and exits at another v Shock occurs when you touch: both wires of an electric circuit;both wires of an electric circuit; one wire of an energized circuit and ground; orone wire of an energized circuit and ground; or a metallic part that is “hot”a metallic part that is “hot” 3a

Electric shock v Severity of shock depends on the: amount of currentamount of current path of the currentpath of the current amount of time exposedamount of time exposed 3b

Electric shock v Effects range from a tingle, to cardiac arrest, severe burns, and probable death v Typical household current of 15 amps can cause death 3c

Electricity’s Physiological Effect v amps v amps v amps v v v v Barely felt v “let go” threshold v Muscular paralysis v Ventricular fibrillation v 100 Watt light bulb v Common household fuse

1-8 mA = shock, not painful 8-15 mA = Pain 8-15 mA = Pain mA = Muscle contraction mA = Muscle contraction mA = Severe pain & paralysis of breathing muscles mA = Severe pain & paralysis of breathing muscles mA = Ventricular fibrillation (Usually cause death) (Usually cause death) > 1,000 mA = Heart stops > 1,000 mA = Heart stops Effects of Current

Grounding v Protects you from electrical shock v Safeguards against fire v Protects electrical equipment from damage 4a

Grounding v Two types of grounding include: Service or system groundService or system ground Equipment groundEquipment ground 4b

Circuit protective devices v At construction sites, the most common electrical hazard is the ground fault electrical shock v OSHA requires either: Ground fault circuit interrupters (GFCIs); orGround fault circuit interrupters (GFCIs); or Assured Grounding Conductor ProgramAssured Grounding Conductor Program 5a

Circuit protective devices v Circuit protective devices include: fuses and circuit breakers - protect conductors and equipmentfuses and circuit breakers - protect conductors and equipment GFCIs - limit or shut off current flowGFCIs - limit or shut off current flow 5b

Ground fault circuit interrupters v A fast-acting circuit breaker that senses small imbalances in the circuit caused by current leakage to ground 6a

PLUG COIL LOAD HOT NEUTRAL 1 AMP PLUG COIL LOAD HOTNEUTRAL 1000 mA 995 mA 5 mA GROUND

1000 mA PLUG COIL LOAD HOT NEUTRAL 1000 mA 1 AMP 5 mA GROUND 995 mA

Polarity

Assured Equipment Grounding Conductor program v If GFCIs are not used, employers must have a scheduled and recorded Assured Equipment Grounding Conductor program 7a

v The AEGC program is an inspection program covering: all cord setsall cord sets receptacles that are not part of a permanent wiring structurereceptacles that are not part of a permanent wiring structure equipment connected by cord and plugequipment connected by cord and plug 7b Assured Equipment Grounding Conductor program

v Equipment must be visually inspected for damage/defects before each day’s use 7c Assured Equipment Grounding Conductor program

v 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 test –grounding conductor test 7d Assured Equipment Grounding Conductor program

Lockout/Tagout v Electrical equipment deactivated for repair must be locked out and tagged at the point where it can be energized v Protects maintenance workers v Warns others that work is being performed 8a

Lockout/Tagout v Only the person who locked/tagged the equipment can turn it back on v Before equipment is energized, a qualified person must conduct tests and visual inspections 8b

Lockout/Tagout v Each lock/tag must be removed by the person who applied it 8c

Lockout/Tagout v If the employee is absent, the lock/tag can be removed by a qualified person if: the employee who applied the lock has left the premisesthe employee who applied the lock has left the premises it is visually determined that all employees are clear of the circuits/equipmentit is visually determined that all employees are clear of the circuits/equipment 8d

Guarding requirements v Any live parts of electrical equipment operating at 50 volts or more must be guarded to avoid accidental contact 9a

Guarding requirements v Entrances to areas with live electrical parts must be marked with warning signs v Signs should forbid entrance except by qualified persons 9b

Insulation v Check equipment daily for insulation breakdown v Check for: exposed wiresexposed wires broken wiresbroken wires scuffed insulation on extension cordsscuffed insulation on extension cords 10a

Insulation v Use non-conducting mats, shields, or barriers when necessary v Use non- conducting coatings on hand tools 10b

Personal protective equipment v Employers must provide electrical protective equipment to employees who work near electrical hazards 11a

Personal protective equipment v Use appropriate equipment for the hazards, including: helmetshelmets eye and face protectioneye and face protection gloves and sleevesgloves and sleeves apronsaprons protective footwearprotective footwear 11b