Fundamentals of Electricity
- There must be a completed path (circuit) stemming from and returning to the power source (battery, transformer) in order for electricity to flow.
- Electrical current has the ability to flow through humans and other conductors, such as earth, metals and concrete.
- Insulators are resistant the flow of electricity. Insulating materials are used to create electrical work gloves and are used to coat copper conducting wires. Insulators help shield individuals from coming into contact with flowing electricity.
- Even when there is not electricity flowing through receptacle, there is still “potential” electricity in the receptor that can cause shock.
How Electricity Can Hurt You
There are 3 types of potential injuries that can result from electrical shock passing through yout body:
- Burns (arcs burn with heat & radiation)
- Broken bones, Falls, muscle damage (physical injuries)
o At 10 mA, the muscles clamp on to whatever the person is holding.
- Nervous system effects (cease breathing at 30 to 75 mA alternating current at 60Hz, fibrillation at 75 to 100 mA at 60Hz)
o Fibrillation = heart is "twitching" and there is no longer blood flow to the body.
- As the heart is in the path that most electrical currents will take through the body, it can easily be damaged from shock:
o Hand-to-hand
o Hand-to-foot
Use OSHA Safe Work Practices
Reduce/control hazards though safe work practices:
- Plan your work in advance and plan for safe work practices
- Avoid working in wet conditions whenever possible
- Use Ground Fault Circuit Interrupters. GFCI's are electrical devices that are designed to detect earth faults (when current is "leaking" someplace outside its intended pathway). Your body provides a path for electricity to reach the ground, if you come into contact with “leaking” electricity you could be shocked or electrocuted. GFCI's should be utilized in all wet locations as well as on outdoor power outlets.
- Be sure to avoid overhead power lines whenever possible. Position yourself so that you never become closer them 10ft to an overhead power line when using a conductive object (power saws, posts, tools, brooms, etc.) Use appropriate wiring and connectors
- Always use extension cords correctly and temporarily:
o All cords must have 3 prongs and be UL listed
o There must be a fuse or breaker in all power bars used
o Do not use 2-prong, ungrounded cords in a lab
o Do not run wires under carpets, through walls, doors, or across aisles
- These may become damaged or present a tripping hazard
o Don't attempt to fix cords--buy new ones
o Make sure the total number of watts joined to the wire does not exceed the rating of the wire.
- Use and maintain tools properly
- Avoid wearing metal or conductive items that may come into contact with energized parts. Such as jewelry, watch bands, bracelets, rings, key chains, necklaces, etc.
- Wear proper PPE:
o Hard hats rated "Class E"
o ANSI-approved footwear coded "EH"
Follow the Administrative Controls
o Safe work procedures
o Follow Lockout and Tagout procedures
o Follow prescribed work practices
o Abide by signs labeling electrical hazards
Use safe equipment
o Do not use equipment that has been damaged or altered.
o Always use equipment based on the specifications of the manufacturer's.
o "Live" parts (greater than 50 volts) need to be guarded by one or more of the following:
o An enclosure that requires a tool for access.
o A secured enclosure.
o An insulating guard to prevent contact which could cause shock.
o Check cords--they should:
o Have no deterioration and damage.
o Always have an appropriate strain relief component in the place where they enter the enclosure