The purpose of this article is to ensure worker safety while working on different kind of projects and at the homes as well. Also to raise the awareness of electrical hazards which may be present around you and how to recognize electrical hazards.
Below document shall explain the ways to eliminate, remove and prevent electrical hazards in the workplace, emphasizing the extreme importance of observing all electrical safety requirements and practices.
Lastly instructing you on what to do during an electrical accident.
An average of one worker is electrocuted on the job every day. An average of one person is electrocuted in the home every 36 hours. Electrical incidents are far more likely to be fatal than other types.
There are four main types of electrical injuries:
- Electrocution (death due to electrical shock)
- Electrical shock
Current: the movement of electrical charge
Resistance: opposition to current flow
Voltage: a measure of electrical force
Conductors: substances, such as metals, that have little resistance to electricity
Insulators: substances, such as wood, rubber, glass, and bakelite, that have high resistance to electricity
Grounding: a conductive connection to the earth which acts as a protective measure
What is an Electrical Shock
An electrical shock is received when current passes through the body, the severity of the shock depends on:
- Path of current through the body
- Amount of current flowing through the body
- Length of time the body is in the circuit
Dangers of Electrical Shock
Currents greater than 75 mA can cause ventricular fibrillation (rapid, ineffective heartbeat)
Will cause death in a few minutes unless a defibrillator is used.
75 mA is not much current, a small power drill uses 30 times as much.
How is an electrical shock received?
When two wires have different potential differences (voltages), current will flow if they are connected together. In most household wiring, the black wires are at 110 volts relative to ground.
The white wires are at zero volts because they are connected to ground.
If you come into contact with an energized (live) black wire, and you are also in contact with the white grounded wire, current will pass through your body and YOU WILL RECEIVE A SHOCK.
If you are in contact with an energized wire or any energized electrical component, and also with any grounded object, YOU WILL RECEIVE A SHOCK.
You can even receive a shock when you are not in contact with a ground.
If you contact both wires of a 240-volt cable, YOU WILL RECEIVE A SHOCK and possibly be electrocuted.
Low Voltage Does Not Mean Low Hazard
A small amount of electrical current can cause injury, even death.
The current from a 7.5-watt, 120-volt lamp, passing across the chest, is enough to cause fatal electrocution.
Deaths from 120 volts represent about 12 percent of all electrocutions
Most common shock-related, nonfatal injury occurs when one touches electrical wiring or equipment that is improperly used or maintained.
Electrical burns typically occurs on the hands, which is in fact very serious injury that needs immediate attention.
Recognize the Electrical Hazards
Have you seen areas or situations like these?
Both situations in below image are NEC violations and present a safety hazard, based on inaccessible circuit control devices.
Do not block the working space around electrical equipment (600 volts, nominal, or less).
This space provides and maintains sufficient access and working space to permit ready and safe operation and maintenance of such equipment.
What do you do if you see the below shown situations?
Call a timeout and inform your supervisor.
Do not remove or open receptacle covers, switch plates, or covers of electrical equipment unless qualified and authorized.
Assume all exposed wiring is energized until proven otherwise. STOP, protect the area and contact supervision if you encounter this situation.
Be careful when you observe potentially energized exposed wires with status unknown.
Tripping and Abrasion Hazards
Don’t cause tripping hazards or create pinch points for cords.
If you must run a cord temporarily across the floor, protect your co-workers by covering the cord appropriately.
Remove from service damaged or frayed cords.
Report electrical equipment damage to your supervisor.
Visually inspect electrical equipment before each use for damage and/or external defects such as loose, missing or deformed parts, pinched or crushed outer jackets or insulation.
This type of external damage may indicate internal damage to the equipment.
Electrical cords that are worn or damaged must be replaced without delay.
Before cleaning electrical equipment, turn it off and unplug it.
Stay clear of bare, exposed wiring and REPORT IT!
Hazards related to Cabinets, Boxes, and Fittings
Junction boxes, pull boxes and fittings must have approved covers in place.
Unused openings in cabinets, boxes and fittings must be closed (no missing knockouts).
Photo shows violations of these two requirements.
Report this situation to management.
Never daisy chain multi-outlet strips (plugging into each other)
Observe all barricades, postings, and warning signs regarding dangerous voltages.
Do not enter or approach electrical work areas unless specifically authorized and qualified.
Electrical boxes with knockouts are designed to be installed in or on walls, not used as multi-outlet extension cords.
Don’t wear loose conductive apparel, (such as rings, watch bands, bracelets, necklaces, etc.) when plugging in electrical cords.
Grounding Path Hazards
The path to ground from circuits, equipment, and enclosures must be permanent and continuous.
Violation shown below is an extension cord with a missing grounding prong.
Do not make alterations to polarized blades or ground pin to make plug fit into non-polarized or non-grounded outlet.
Electrical hazards may exist overhead indoors, crane power rails are an example.
Also electrical hazards may exist overhead outdoors. Most lines are bare and having higher voltage than the normal insulated wiring.
For high voltage lines, contact is not required to initiate an arc or cause shock and burn injuries, therefore maintain safe approach distances when working near energized overhead transmission lines.
Stay at least 10 feet away from overhead lines.
Electrical equipment and wiring must not be exposed to physical damage. Stay away from damaged equipment and report equipment damage to supervision.
Treat it as it is designed to be treated. Pull the plug, not the cord.
Handle portable electrical equipment carefully, in accordance with manufacturers instructions, and in a manner that will not cause damage to cord or equipment.
Clues that Electrical Hazards May Exist
- Tripped circuit breakers or blown fuses
- Hot to the touch on tools, wires, cords, connections, or junction boxes
- Dim and flickering lights
- Sizzles and buzzes-unusual sounds from electrical system
- Odor of hot insulation
- Mild tingle from contact with case or equipment
- GFCI that shuts off a circuit
- Worn or frayed insulation around wire or connection
- Burn marks or discoloration on receptacle plates or plug prongs
Using Ground-Fault Circuit Interrupter
Always use a GFCI receptacle or circuit for cord connected tools and equipment used outdoors or near water.
This device protects you from electrocution.
The GFCI detects a difference in current between the black and white circuit wires (This could happen when electrical equipment is not working correctly, causing current leakage known as a ground fault.)
Perform the test function on the GFCI to determine if it is functioning properly by pushing the button to verify it shuts off, repeated resetting not allowed.
Contact electrician to troubleshoot if GFCI continues to trip.
Prohibited Uses of Flexible Cords
- Substitute for fixed wiring
- Run through walls, ceilings, floors, doors, or windows
- Concealed behind or attached to building surfaces
Safe Practices for Cord Control
Do not fasten electrical cords to surfaces with staples, nails, wire, or any other method that might damage the cord.
Place the extension cords in appropriate locations and understand they are for temporary use only.
For all the tool cords, keep track of them, to assure they do not become damaged.
Do not plug or unplug electrical cords with wet hands or while standing in water.
Do not use portable electrical equipment or extension cords in wet or damp locations without a ground fault circuit interrupter (GFCI) ahead of the plug connection, GFCIs are also required for temporary power applications in wet or damp locations, including extension cords.
Remove loads from an appliance or extension cord before unplugging it.
If a plug wont stay placed snugly or fits loosely in a receptacle, don’t use, replace it
Safe Practices of Resetting Breakers
When circuit breakers and fuses trip, don’t reset or replace them!
Only qualified and authorized personnel are allowed to reset breakers and replace fuses.
Contact qualified personnel to determine the cause of trips.
Wall Penetrations Safety Practices
When penetrating walls to hang pictures, bulletin boards, signs, understand and follow site requirements to ensure that concealed electrical wiring, conduit or piping will not be contacted.
A non-obtrusive survey (e.g., Ground Penetrating Radar, proximity detection device) may be required, along with a review of applicable drawings, to ensure that the electrical system is not penetrated or contacted.
Safe Practices Handling & Using Equipment’s
Consumer electrical equipment or appliances should be tested and labeled by a recognized testing laboratory. (Look for the UL, CSA, ETL or MET Label).
Always read and follow the manufacturers instructions carefully. Be sure that the equipment or tool is rated for the environment (wet, damp, etc.).
Plug portable space heaters directly into outlet. Do not use extension cord. Use a circuit with as little else on it as possible since space heaters take a lot of power.
Do not remove/replace receptacle covers, switch plates, or covers of electrical equipment that may contain energized conductors without electrical qualifications and authorization.
Only qualified electrical workers may perform activities such as electrical probing, measuring and testing electrical energized components (such as performing an absence of voltage test).
Handling the Electrical Emergencies
Do you know what dangers could be encountered?
Attempts to rescue an accident victim may pose as great a hazard for the rescuer as it does for the victim.
A victim of an electrical accident is often unable to move or release the electrical conductor, because of muscle clamping.
Caution should be a primary consideration during any electrical accident or emergency.
Do you know the proper actions to take if you see someone receiving a shock or locked onto an energized electrical line?
While approaching the accident:
- Never rush into an accident situation-Assess your own safety
- Call 911 as soon as possible
- Unplug portable electrical equipment to remove power (1st choice)
- Open a disconnecting device or circuit breaker to de-energize fixed electrical equipment
- Use a dry wood broom, leather belt, plastic rope, or something similar that is non-conductive such as wood or plastic cane with hook on the end to free the person from the energy source.
Electrical Emergencies for Downed Power Lines
While approaching the accident:
Move away from downed power line.
Shuffle away with small steps keeping feet together.
If you see someone in direct contact with line, do not touch person.
Call 911 as soon as possible.
Do not attempt to move downed power line.
Get the aid of trained electrical personnel if possible.
If you are in your car and it is it contact with the downed line, stay in car. Honk horn for help and tell others to stay away from your vehicle.
Summary of the learning and Actions
Inspect your work areas for existing unsafe conditions i.e.
- Bare wires
- Open enclosures containing exposed wires
- Loose or missing covers or fasteners
Use good electrical safe practices i.e.
- No daisy-chaining
- No overloading outlets
- Pull on plug, not cord
What to do if you identify a hazardous condition?
When unsafe electrical conditions are found, correct them if possible, or take steps to warn other employees.
Report unsafe electrical conditions verbally and/or in writing to supervision so corrective actions can be taken immediately.
Barricade the area, if an immediate electrical hazard exists.
Notify supervision for correction and necessary documentation.