Electrical Safety - Construction

OSHA Office of Training & Education

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Learning Objectives
• The dangers of electricity
• Working Safely around overhead power lines
• Familiarization with:
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Temporary power panels
Temporary power circuits
Temporary lighting circuits
Extension Cords and power tools
Assured Grounding
Portable Ground Fault Circuit Interrupters
Lock-out Tag-out
OSHA Office of Training & Education

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OSHA Office of Training & Education

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Have you ever wondered what idiots looks like? Well, wonder no more!

YES THAT IS A POWER CORD
FLOATING ON FLIP FLOPS
OSHA Office of Training & Education

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Electricity - The Dangers
• About 5 workers are electrocuted every week
• Causes 12% of young worker workplace deaths
• Takes very little electricity to cause harm
• Significant risk of causing fires OSHA Office of Training & Education

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Electrical Injuries
There are four main types of electrical injuries:
• Direct:
Electrocution or death due to electrical shock
Electrical shock
Burns
• Indirect - Falls
OSHA Office of Training & Education

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Electrical Shock
An electrical shock is received when electrical current passes through the body.
You will get an electrical shock if a part of your body completes an electrical circuit by…
• Touching a live wire and an electrical ground, or
• Touching a live wire and another wire at a different voltage.

OSHA Office of Training & Education

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Shock Severity
• Severity of the shock depends on:
Path of current through the body Amount of current flowing through the body (amps)
Duration of the shocking current through the body,
• LOW VOLTAGE DOES NOT
MEAN LOW HAZARD

OSHA Office of Training & Education

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Dangers of Electrical Shock
• Currents above 10 mA* can paralyze or “freeze” muscles.
• Currents more than 75 mA can cause a rapid, ineffective heartbeat -- death will occur in a few minutes unless a defibrillator is used
• 75 mA is not much current – a small power drill uses 30 times as much Defibrillator in use

* mA = milliampere = 1/1,000 of an ampere
OSHA Office of Training & Education

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Burns
• Most common shock-related injury • Occurs when you touch electrical wiring or equipment that is improperly used or maintained • Typically occurs on hands
• Very serious injury that needs immediate attention

OSHA Office of Training & Education

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Falls
• Electric shock can also cause indirect injuries
• Workers in elevated locations who experience a shock may fall, resulting in serious injury or death

OSHA Office of Training & Education

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Electrical Hazards and How to
Control Them
Electrical accidents are caused by a combination of three factors:
Unsafe equipment and/or installation,
Workplaces made unsafe by the environment, and
Unsafe work practices.
OSHA Office of Training & Education

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Overhead Power Lines

OSHA Office of Training & Education

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OSHA Office of Training & Education

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Power Line Facts
• Overhead lines are typically not insulated. Any covering is generally a weather protection, not insulation. • Over 90 percent of the contacts occur on overhead distribution lines
• Operators are normally safe if they stay on the equipment • Ground personnel are over 8 times more likely to be killed
OSHA Office of Training & Education

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Hazard - Overhead Power Lines
• Examples of equipment that can contact power lines:
 Crane
 Ladder
 Scaffold
 Backhoe
 Scissors lift
 Raised dump truck bed
 Aluminum paint roller

OSHA Office of Training & Education

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Electrical Damage to the Body
• If you touch a power line, electricity will attempt to travel through your body
• When electricity travels through the body, it heats up and burns body tissue internally • Electricity leaves the body violently, causing burns or even blowing an exit hole
OSHA Office of Training & Education

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Maintain Safe Working Clearance
• For lines rated over 50 kV., minimum clearance between the lines and any part of the crane or load shall be