Electrical Safety for Construction Electrical regulations v Subpart

Electrical Safety for Construction

Electrical regulations v Subpart K of 29 CFR 1926 1 a

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

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

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

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

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

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

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

Human Resistance Body Area Dry Skin Wet Skin Internal Organs Ear to Ear OHMS 600, 000 1, 000 400 -600 100

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

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; • one wire of an energized circuit and ground; or • a metallic part that is “hot” 3 a

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

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 3 c

Electricity’s Physiological Effect 00. 001 amps v 00. 015 amps v 00. 020 amps v 00. 100 v 01. 200 v 15. 000 v v v v Barely felt “let go” threshold Muscular paralysis Ventricular fibrillation 100 Watt light bulb Common household fuse

Effects of Current 1 -8 m. A = shock, not painful 8 -15 m. A = Pain 15 -20 m. A = Muscle contraction 20 -100 m. A = Severe pain & paralysis of breathing muscles 100 -1000 m. A = Ventricular fibrillation (Usually cause death) > 1, 000 m. A = Heart stops

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

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

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); or • Assured Grounding Conductor Program 5 a

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

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

1 AMP COIL 1 AMP PLUG HOT 1 AMP NEUTRAL LOAD 1000 m. A COIL 995 m. A PLUG HOT 5 m. A NEUTRAL GROUND LOAD

1000 m. A COIL 995 m. A 1000 m. A PLUG HOT 5 m. A NEUTRAL 1 AMP GROUND LOAD

Polarity

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

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

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

Assured Equipment Grounding Conductor program v Tests must be performed: • before the first use of new equipment • after suspected damage to equipment • at three month intervals – continuity test – grounding conductor test 7 d

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 8 a

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 8 b

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

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 premises • it is visually determined that all employees are clear of the circuits/equipment 8 d

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

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 9 b

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

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

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

Personal protective equipment v Use appropriate equipment for the hazards, including: • helmets • eye and face protection • gloves and sleeves • aprons • protective footwear 11 b