Technicians must always work safely. Following electrical safety rules is required when working with electrical and electronic equipment to help prevent injuries caused by electrical energy sources. Electrical safety has been advanced by the efforts of the National Fire Protection Association (NFPA), the Occupational Safety and Health Administration (OSHA) and state safety laws. The NFPA is a non-profit organization that assists in determining the hazards of combustion products and sponsors the development of the National Electrical Code (NEC).

National Electrical Code

The NEC is one of the most widely used and recognized electrical consensus standards in the world. The purpose of the NEC is to protect people and assets from the dangers associated with the use of electricity. Improper procedures when working with electricity can cause permanent injury or death. The NEC is used by several local, state and federal agencies to establish electrical installation requirements. The NEC is updated every three years. Electrical safety rules include the following:

  • Always comply with the NEC, state and local codes.
  • Use Underwriters Laboratories (UL) approved equipment, components and test equipment.
  • Check to see if the circuit's switch is open or disconnected before removing any fuses. Use an authorized fuse puller to remove fuses and break the contact on the line side of the circuit first. When installing fuses, start with the load side of the fuse clip and work your way to the line side.
  • Inspect and test grounding systems for proper operation. Ground any conductive component or element that is not energized.
  • Turn OFF, lock out and tag out any circuit that does not need to be energized when maintenance is being performed.
  • Always use personal protective equipment (PPE) and safety equipment.
  • In the event of an emergency, perform the appropriate operation.
  • Use only a Class C fire extinguisher on electrical equipment. Blue inside a circle identifies a Class C fire extinguisher.
  • Always work with another individual when working in a dangerous area, on dangerous equipment or with high voltages.
  • Do not work when tired or taking medication that causes drowsiness unless specifically authorized by a physician.
  • Do not work in poorly lit areas.
  • Ensure there are no atmospheric hazards such as flammable dust or vapor in the area.
  • When working on a live circuit, use one hand to lessen the possibility of an electrical shock to the heart and lungs.
  • Do not bypass fuses, circuit breakers or any other type of safety equipment.

Electrical shock

Electrical shock occurs when a person's body meets an electrical circuit. Electrical shock effects vary from a mild sensation to paralysis or death. Also, severe burns may occur where the current enters and exits the body. The amount of electric current flowing through the body in milliamps (mA), the length of time the body is subjected to the current, the direction the current takes through the body, and the physical size and condition of the body through which the current flows all determine the severity of an electrical shock. These differing current values indicate a ground fault in which the missing return current may take an alternate path to the ground through an operator. This could result in severe injury or even death. Ground-fault circuit interrupters (GFCIs) are used to help prevent electrocutions and react quickly to a current imbalance, usually in less than one-tenth of a second. GFCIs should be installed where electrical circuits may accidentally meet water, such as in kitchens, bathrooms, laundry rooms and garages. GFCIs do not protect individuals from line contact hazards.

Individuals who work on or near electrical equipment must have respect for all voltages, have knowledge of the principles of electricity and follow safe work procedures. All technicians should be encouraged to take a basic course in cardiopulmonary resuscitation (CPR), so they can aid a coworker in emergencies.

During an electrical shock, the body of a person becomes part of an electrical circuit. The resistance of a person's body to the flow of current varies. Sweaty hands have less resistance than dry hands. Standing on a wet floor provides less resistance than standing on a dry floor. Lower resistance increases the current flow— the severity of the electrical shock increases as the current increases.

If a person is receiving an electrical shock, power must be removed as quickly as possible. If the disconnect switch for the equipment circuit is nearby and can be operated safely, the power must be shut off. If power cannot be removed quickly, the victim must be removed from contact with the live parts. Insulated protective equipment, such as a hot stick, rubber gloves, wood poles or plastic pipes, can be used to separate the victim from the energized circuit. When free from the electrical hazard, the victim must receive immediate medical attention.

Grounding

The connection of all exposed non-current-carrying metal components to the Earth is known as grounding. Grounding protects equipment and personnel from the dangers of electrical shock by providing a direct path to Earth for unwanted fault current. Unwanted current may exist because of insulation failure or because a current-carrying conductor contacts a non-current-carrying part of the system.

Grounding is accomplished by connecting a circuit to a metal underground water pipe, a metal frame of a building, a grounding conductor, a ground ring or a concrete-encased electrode. To prevent problems, the grounding path must be as short as possible and of sufficient diameter (as recommended by the NEC), must never be fused or switched, must be a permanent part of the electrical circuit, and must be continuous and uninterrupted from the electrical circuit to the grounding electrode.

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