Electrical Safety for Construction

Electrical Safety for Construction

Electrical regulations Subpart K of 29 CFR 1926 1a

Electrical regulations 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 1b

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

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

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

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

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

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

Electric shock Occurs when current enters the body at one point and exits at another 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” 3a

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

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

Electricity’s Physiological Effect 00.001 amps 00.015 amps 00.020 amps 00.100 01.200 15.000 Barely felt “let go” threshold Muscular paralysis Ventricular fibrillation 100 Watt light bulb Common household fuse

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

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

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

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

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

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

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

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

Polarity

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

Assured Equipment Grounding Conductor program 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 7b

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

Assured Equipment Grounding Conductor program 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 7d

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

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

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

Lockout/Tagout 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 8d

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

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

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

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

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

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