Basic Electrical Safety

For non-Electrical Staff

Electricity is an integral part of today's modern world, and sometimes it is easy to forget just how dangerous it can be. Given the correct circumstances, it can kill. But it can also shock you painfully, damage sensitive equipment, and ignite combustible materials.  This training module will cover some basic safety rules you should follow in regards to electrical safety.  This training is basically for those who are unqualified to be electricians, but whose work may be performed close to electrical systems. 

 Deaths. Electrocutions rank FOURTH (9%) in causes of industrial FATALITIES (behind traffic, violence and construction). The National Safety council estimates 600 people die every year of electrical causes. Most of these accidents involve low voltage (600 volts or less).  Roughly 3,600 disabling electrical contact injuries occur every year in the United States, along with another 4,000 non-disabling injuries.

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A small night-light with a 6-watt bulb draws .05 ampere, and even that small amount of current can be fatal. Here are some effects of current (in milli amps) passing through a 150 pound body (note that perception is only .5 to 1.5 milli amps):

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Unsafe Acts  There are 2 reasons for unsafe acts:  We know better but intentionally do something unsafe.  We don't know better.

Avoid the following unsafe acts:  Failure to de-energize, lockout & tagout hazards during maintenance, repair or inspections.  Use of defective and unsafe tools.  Use of tools or equipment too close to energized parts.  Not draining off stored energy in capacitors.  Using 3-wire cord with a 2-wire plug.  Removing the third prong (ground pin) to make a 3-prong plug fit a 2prong outlet.  Overloading outlets with too many appliances.  Using the attached electrical cord to raise or lower equipment.  Not verifying power is off when making repair (drilling into a 110 Volt a.c. line can kill).  Working in an elevated position near overhead lines.

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Unsafe Equipment Some common causes of unsafe equipment:      

Loose connections Faulty insulation Improper grounding (removal of 3rd prong) Use of "homemade" extension cords Defective parts Unguarded live parts--for example: ▪ Bare conductors or exposed terminals ▪ Metal parts of equipment may become energeized when connected by cord or plug. Capacitance may cause up to 55% of line voltage to be stored on the casing of metal tools.

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Hazardous Environments  Use special precautions when working in potentially

hazardous environments and situations. Even an accidental static discharge can cause a fire or explosion in areas where the following are present: ▪ ▪ ▪ ▪ ▪

Flammable vapors, liquids and gasses Combustible dusts Corrosive atmospheres Explosive environments Poor housekeeping: blocked electrical boxes, flammable materials stored in equipment rooms, lack of proper hazard signs, excess clutter.

Know about electricity and how it can harm you and your colleagues.

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Basics of Electricity:  Electrical current will not flow unless it has a complete path 

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(circuit) that returns to its source (battery, transformer). Current flows through you and other conductors, such as metals, earth and concrete. Current can harm you when it flows through your body (electric shock). Insulators resist the flow of electricity. Insulating materials are used to coat copper conducting wires and are used to make electrical work gloves. Insulators help to protect humans from coming into contact with electricity flowing through conductors. Just as there is pressure in a water pipe, even with no water flowing, there is voltage at a receptacle, even if current is not flowing. Another word for voltage is "Potential."

How Electricity Can Harm You Current passing through your body can cause electric shock, resulting in 3 types of potential injuries:  Burns (arcs burn with heat & radiation)  Physical injuries (broken bones, falls, & muscle damage)  

 At 10 mA, the muscles clamp on to whatever the person is holding.

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Nervous system effects (stop breathing at 30 to 75 mA alternating current at 60Hz, fibrillation at 75 to 100 mA at 60Hz)  Fibrillation = heart is "twitching" and there is no blood flow to the

body.

The heart can be damaged because it is in the path of the most common routes electricity will take through the body:  Hand-to-hand  Hand-to-foot 

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Know about static electricity and how it can do harm. Minimize your exposure to static shocks.  Never clean the glass face of your computer monitor while the

computer is on.  During normal operation, the glass surface of a monitor's CRT accumulates an electrostatic charge. When you touch the screen with a finger, the charge is from the portion of the screen you touched and it discharges through your finger with a tiny spark. Electric current does not normally flow through glass, so only the part of the screen that your finger touches is discharged.  However, when you clean a monitor the entire glass is wet and the charge on the entire screen will discharge to your finger or hand, causing a much more painful shock.  You can be injured by the reaction to the shock even though such shocks in themselves are not hazardous.

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Control hazards though safe work practices:  Plan your work and plan for safety  Avoid wet working conditions and other dangers  Use Ground Fault Circuit Interrupters. GFCI's are electrical

devices that are designed to detect ground faults (when current is "leaking" somewhere outside its intended pathway). If your body provides the path to ground for the leaking current, you could receive a shock or be electrocuted. GFCI's should be used in all wet locations and on outside outlets.  Avoid overhead power lines: Position yourself so that the longest conductive object you are using (saws, poles, tools, brooms, etc.) cannot come closer than at least 10 feet to any unguarded, energized overhead line.  Use proper wiring and connectors

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Control hazards though safe work practices:  Use extension cords properly and temporarily: ▪ ▪ ▪ ▪ ▪ ▪

Cords must be UL listed and have 3 prongs Power bars must have a fuse or breaker Do not use 2-prong, ungrounded cords in a lab Do not run cords through walls, doors, under rugs, or across aisles Do not repair cords--buy new ones Make sure the total number of watts connected to the cord does not exceed the rating of the cord.

 Use and maintain tools properly  Avoid wearing items such as jewelry, watch bands, bracelets, rings,

key chains, necklaces, etc. that might come into contact with exposed, energized parts.  Wear correct PPE: ▪ Hard hats rated "Class E" ▪ ANSI-approved footwear coded "EH"

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Follow the Administrative Controls  Safe work procedures  Lockout and Tagout

 Proscribed work practices  Signs warning of electrical hazards

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Use safe equipment  Do not use equipment that has been damaged or improperly

modified.  Always use equipment according to the manufacturer's specifications.  "Live" parts (greater than 50 volts) must be guarded by one or more of the following: ▪ ▪ ▪ ▪

An enclosure that requires a tool for access. A locked enclosure. An interlocked access door. A substantial insulating guard to prevent contact.

 Check cords--they should: ▪ Be completely free of damage and deterioration. ▪ Should always have an appropriate strain relief device where they enter the enclosure.

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Electrical Shock  Protect yourself Don't touch the person. That

person might be energized, so take time to protect yourself.  Don't try to use a conductive tool to free the person.  Don't touch anyone who has become grounded.

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Electrical Shock  Call 998 for help, IF the person: is obviously

injured (loss of consciousness, significant trauma, etc.)  has an altered mental status (confusion, slow/slurred speech, etc.)  has other obvious injury (laceration, burn, etc.)

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Electrical Shock If You Are Trained:  Keep others from being harmed  Shut off the power (fuse or circuit-breaker or pull the plug; this

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might be difficult because there might be secondary sources; if you are not sure, get help) Move the victim to safety only when power is OFF and no neck or spine injuries are possible Give necessary first aid (keep CPR training up-to-date). Report accident to supervisor (even minor shocks and close calls must be reported) Secure area Collect data for an investigation and to prevent reoccurrence.

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What To Do Until Aid Arrives:  Check for: ▪ Pulse If person's heart has stopped, start CPR, if you are trained. ▪ Breathing If person isn't breathing, begin mouth-tomouth resuscitation, if you are trained.  Treat for shock Keep person lying down. ▪ If unconscious, put them on their side to let fluids drain. ▪ Don't move the person if neck or spine injuries are possible. ▪ Cover the person to maintain body heat