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4.6 Electrical Safety

4.6 Electrical Safety

These guidelines provide information that will safeguard those who work with and around electricity.

4.6.1 General Requirements

  • Maintain sufficient access and working space around all electrical equipment to permit ready and safe operation and maintenance of the equipment. The working space in front of the electrical equipment should be the width of the equipment or 30 inches (0.75 m), whichever is greater.

  • Guard all live parts of electrical equipment operating at 50 volts or more against accidental contact by using approved enclosures and covers.

  • Use suitable guards to protect all lamps in light fixtures lower than seven feet (2.1 m) from accidental contact or breakage.

  • Where possible, use ground-fault relays (or sensors) to sense low-magnitude ground faults to help protect personnel.

    • A ground-fault circuit interrupter (GFCI), a type of ground-fault relay, is defined as “a device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time” (“Article 100,” in NFPA 70: National Electrical Code 2017, 18).

  • Workers not qualified to work near exposed energized or de-energized overhead lines should stay a minimum of 10 feet away from any unguarded equipment.

4.6.2 Moisture

Any type of moisture may provide a conductive path for electricity, resulting in a deadly shock. All employees should follow these guidelines regarding moisture when working with and around electricity:

  • Use a ground fault circuit interrupter when there is water present.

  • Use power tools, cords, and outlets approved for outdoor use if exposed to moisture.

  • Limit electrical work during rainy conditions.

4.6.3 Atmosphere

Make a reasonable effort to ensure there are no atmospheric hazards in the work area, such as:

  • Dust particles.

  • Flammable vapors.

  • Excess oxygen.

A stray spark in these conditions might cause an explosion or fire. Ventilate your work area to lower the concentration of atmospheric hazards.

4.6.4 Clothing and Jewelry

Remove all jewelry, including rings and metal wristwatches. Gold and silver are dangerously efficient electrical conductors.

Employees who have a specific assignment (such as lineman, electrician, electronics maintenance) that requires them to work constantly and directly with electricity must use the PPE required for the jobs they perform. This clothing and equipment should be arc rated and may consist of gloves, hoods, sleeves, face shield, hard hats, rubber matting, and blankets.

4.6.5 Tools

Worn, defective, or carelessly operated tools are the direct cause of many electrical accidents. Always choose the right tool for the job, and use it correctly. Before you start any job, inspect all tools to be sure they are clean, dry, and free of oily film or carbon deposits. Never modify tools or electrical equipment without proper authorization.

Use these guidelines for hand tools:

  • Hand tools should have manufacturer-installed insulated grips.

  • Use insulated tools when working on energized or live circuits.

  • Never try to improvise tool insulation.

  • Do not use any tool with cracks, tears, or gaps in the insulation.

Use these guidelines for power tools:

  • Make sure that all power tools and equipment is connected only to power sources that have ground-fault protection, such as GFCI or its equivalent, during maintenance work; remodeling; repair of buildings, structures, or equipment; or during other construction-like activities. Power cords with ground-fault protection incorporated into the cord may also be used.

  • Ensure that power tools have double-insulated casings or a three-prong plug (plug with a grounding post).

  • Inspect the overall condition of tools for wear or defects.

  • Check tools to be sure all safety guards or shields are in place.

  • Inspect all power cords and switches for cuts, frayed insulation, exposed terminals, and loose connections.

4.6.6 Electrical Outlets and Extension Cords

Use the following rules regarding electrical outlets and extension cords to help prevent injury, fires, and overloaded wall outlets and extension cords:

  • Always use grounded electrical outlets; do not overload them.

  • Never remove the grounding post from a three-prong grounding plug to make it fit into a two-prong wall socket.

  • Do not route extension cords through doorways, windows, or holes in walls unless you do something to prevent the cord from being cut or pinched. Extension cords should not be used as a permanent power source.

  • Never use an extension cord with cut or damaged insulation. Do not tape over the damaged cord and use it as if it had not been damaged. Extension cords and portable cables should not be used with splices unless the splices are permanently molded, are vulcanized, or are another approved type.

  • Extension cords may only be used during remodeling; maintenance; repair of buildings, structures, or equipment; and similar activities. Extension cords should be removed immediately upon completion of the project or activity for which the cord was installed. Extension cords should not be used as a permanent power source.

  • Ensure that all outlet boxes, junction boxes, and fittings have been provided with covers or faceplates.

  • Electrical cords should be fully insulated and free of damage, including nicks or breaks, for the entire length, from plug to appliance. If insulation, plugs, or connectors are damaged or replaced, they should be repaired to the same level of integrity and quality as the original cord or discarded.

  • Electrical cords should be free from tape, pinching, and stress that could lead to insulation or wire failure.

  • Avoid connecting power strips or extension cords in a series (daisy-chaining).

4.6.7 Small Personal Appliances

Comply with the following rules regarding small personal appliances to prevent injury, fires, and overloaded outlets or extension cords:

  • Before using small appliances such as personal fans, space heaters, toasters, and so forth, ensure that there are enough outlets, electrical capacity, and configurations to support the intended use.

  • All appliances must be certified by Underwriters Laboratories (UL) or other recognized standards that demonstrate the appliance meets or exceeds safe electrical criteria.

  • Appliances need to be rated for commercial use (which usually requires that the electrical components are contained within a metal housing and rated for high or extended usage).

  • Appliances should be regularly inspected in order to ensure that they are safe to use and to educate the user of conditions under which the appliance may become unsafe.

  • Do not allow approved personal appliances to operate unattended.

  • Ensure that the appliances are clean of debris that can damage performance or cause electrical hazards. Devices should be removed from service and appropriately disposed of when they demonstrate signs of failing (making sparks, overheating, smelling like something is burning, shocking users, and so forth).

4.6.8 Lockout/Tagout

Always follow lockout/tagout procedures (see section 4.15, “Hazardous Energy Control (Lockout/Tagout) Program”) before working on circuits or equipment that are or have been electrically charged.

4.6.9 Energized Electrical Work

These guidelines are to help provide a practical, safe working area for employees who face the hazards arising from the use of electricity.

Electrical work on energized equipment should only be performed when necessary. Before performing the work with the equipment energized, every option should be considered that will allow employees to work with the equipment de-energized in an electrically safe working condition. Follow section 4.15, “Hazardous Energy Control (Lockout/Tagout) Program,” to place the equipment in an electrically safe working condition. These are the minimum guidelines that should be followed if it is infeasible to place the equipment in an electrically safe work condition and if work on energized equipment is necessary. Some examples of these situations might include interruption of life-support equipment, deactivation of emergency alarm systems, or troubleshooting.

Definitions

Arc-Flash BoundaryThe distance at which a person will be safe from the source of a potential arc flash. This boundary can protect a person from a second-degree burn if an electrical arc flash were to occur. This distance is typically 3 to 14 feet away from the source.

Arc Flash HazardA dangerous condition associated with the possible release of energy caused by an electric arc.

Arc RatingThe value attributed to materials that describes how well they resist exposure to an electrical arc discharge. The arc rating is expressed in calories/cm2. Arc-rated clothing or equipment indicates that it has been tested for exposure to an electric arc.

Balaclava (Sock Hood)An arc-rated hood that protects the neck, head, and face except for the eyes and nose.

De-energizedFree from electrical charge and from any electrical connection to a source of potential energy.

Electrically Safe Work ConditionA state in which an electrical conductor or circuit part has been disconnected from energized parts and has been locked and tagged in accordance with established standards.

Energized Electrical WorkAny work on energized electrical equipment, circuits, devices, or systems in which an employee is required to deliberately or may accidentally place a part of his or her body, tool, or other material in contact with electrical devices. These electrical devices have been deemed to be in excess of 50 V. Energized electrical work is dangerous regardless of the PPE a person is wearing.

Incident EnergyThe amount of thermal energy impressed on a surface at a certain distance from the source that is generated during an electrical arc event. Incident energy is typically expressed in calories per square centimeter (cal/cm2).

Limited-Approach BoundaryThe distance at which a person will be safe from an exposed, energized electrical conductor or circuit part that presents a shock hazard. This distance is typically 3 to 5 feet away from the source.

Nominal VoltageAn approximate value assigned to a circuit or system for the purpose of conveniently designating its voltage class (for example, 120/240 V, 480/277 V, 600 V).

Qualified PersonOne who has demonstrated skills and knowledge related to the construction and operation of electrical equipment and installations. A qualified person has also received safety training to identify and avoid the hazards involved.

Restricted-Approach BoundaryThe distance at which a person will be safe from an exposed, energized electrical conductor or circuit part that presents an increased likelihood of electric shock due to electrical arc-over and the possibility of the person inadvertently coming into contact with the electrical source. This boundary is for personnel working in close proximity to the energized electrical conductor or circuit part. This distance is typically 1 foot away from the source.

Shock HazardA dangerous condition associated with the possible release of energy caused by contact or approach to energized electrical conductors or circuit parts.

General Guidelines

  • Conductive articles of jewelry and clothing (such as watchbands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread, metal headgear, or metal-framed glasses) cannot be worn within the restricted approach boundary.

  • Employees must not reach blindly into areas that might contain exposed, energized electrical conductors.

  • Where necessary, barricades and safety signs must be used to prevent or limit employee access to work areas containing energized conductors. Barricades must not be placed closer than the arc flash boundary.

  • Once energized electrical work is completed, replace all covers, guards, and barriers.

Incident Energy Analysis

  • The facilities manager must perform an incident energy analysis on all electrical equipment, such as switchboards, panelboards, industrial control panels, and motor control centers. An incident energy analysis will help identify the potential amount of incident energy that may be released during an electrical arc event from that specific piece of electrical equipment. Understanding the incident energy level will ultimately help determine the PPE level required to protect employees from serious burns. The incident energy and PPE category can be identified in two ways:

    1. Have a qualified person use table 1, “Arc-Flash Hazard PPE Categories for Alternating Current (AC) Systems.”

    2. Hire an electrical professional to use an industry-accepted method to calculate the incident energy at a specific distance from the electrical equipment, usually 12–18 inches (30–45 cm).

Table 1. Arc-Flash Hazard PPE Categories for Alternating Current (AC) Systems

Equipment

Arc-Flash PPE Category

Arc-Flash Boundary

Panelboards or other equipment rated 240 V and below

Parameters: maximum of 25 kA short-circuit current available; maximum of 0.03 seconds (2 cycles) for fault-clearing time; working distance of 455 mm (18 in.)

1

485 mm

(19 in.)

Panelboards or other equipment rated from 240 V to 600 V

Parameters: maximum of 25 kA short-circuit current available; maximum of 0.03 seconds (2 cycles) for fault-clearing time; working distance of 455 mm (18 in.)

2

900 mm

(3 ft.)

Motor control centers (MCCs), 600-V class

Parameters: maximum of 65 kA short-circuit current available; maximum of 0.03 seconds (2 cycles) for fault-clearing time; working distance of 455 mm (18 in.)

2

1.5 m

(5 ft.)

Motor control centers (MCCs), 600-V class

Parameters: maximum of 42 kA short-circuit current available; maximum of 0.33 seconds (20 cycles) for fault-clearing time; working distance of 455 mm (18 in.)

4

4.3 m

(14 ft.)

600-V class switchgear (with power circuit breakers or fused switches) and 600-V class switchboards

Parameters: maximum of 35 kA short-circuit current available; maximum of up to 0.5 seconds (30 cycles) for fault-clearing time; working distance of 455 mm (18 in.)

2

1.5 m

(5 ft.)

Other 600-V class equipment (277–600 V, nominal)

Parameters: maximum of 65 kA short-circuit current available; maximum of 0.03 seconds (2 cycles) for fault-clearing time; working distance of 455 mm (18 in.)

2

1.5 m

(5 ft.)

Labeling Electrical Equipment

  • All electrical equipment that is likely to require examination, adjustment, servicing, or maintenance while energized—such as switchboards, panelboards, industrial control panels, and motor control centers—shall be labeled with all of the following information:

    1. Nominal system voltage

    2. Arc-flash boundary

    3. At least one of the following:

      • Incident energy and corresponding working distance

      • Arc-flash PPE category (see table 1)

      • Minimum arc rating of clothing (see table 2)

      • Site-specific level of PPE (see table 2)

  • The method used to calculate the information on the label must be documented.

Table 2. Personal Protective Equipment (PPE) for Electrical Hazards Work

PPE

Category

PPE

PPE Category

PPE

1

Arc-Rated Clothing, Minimum Arc Rating of 4 cal/cm2

Arc-rated long-sleeve shirt and pants or arc-rated coverall

Arc-rated face shield or arc-flash suit hood

Arc-rated jacket, parka, rainwear, or hard-hat liner (AN)

Protective Equipment

Hard hat

Safety glasses or safety goggles (SR)

Hearing protection (ear canal inserts)

Heavy-duty leather gloves

Leather footwear (AN)

2

Arc-Rated Clothing, Minimum Arc Rating of 8 cal/cm2

Arc-rated long-sleeve shirt and pants or arc-rated coverall

Arc-rated flash suit hood or arc-rated face shield and arc-rated balaclava (sock hood)

Arc-rated jacket, parka, rainwear, or hard-hat liner (AN)

Protective Equipment

Hard hat

Safety glasses or safety goggles (SR)

Hearing protection (ear canal inserts)

Heavy-duty leather gloves

Leather footwear

3

Arc-Rated Clothing Selected so That the System Arc Ratings Meet the Required Minimum Arc Rating of 25 cal/cm2

Arc-rated long-sleeve shirt (AR)

Arc-rated pants (AR)

Arc-rated coverall (AR)

Arc-rated arc-flash suit jacket (AR)

Arc-rated arc-flash suit pants (AR)

Arc-rated arc-flash suit hood

Arc-rated gloves

Arc-rated jacket, parka, rainwear, or hard-hat liner (AN)

Protective Equipment

Hard hat

Safety glasses or safety goggles (SR)

Hearing protection (ear canal inserts)

Leather footwear

4

Arc-Rated Clothing Selected so That the System Arc Ratings Meet the Required Minimum Arc Rating of 40 cal/cm2

Arc-rated long-sleeve shirt (AR)

Arc-rated pants (AR)

Arc-rated coverall (AR)

Arc-rated arc-flash suit jacket (AR)

Arc-rated arc-flash suit pants (AR)

Arc-rated arc-flash suit hood

Arc-rated glove

Arc-rated jacket, parka, rainwear, or hard-hat liner

Protective Equipment

Hard hat

Safety glasses or safety goggles (SR)

Hearing protection (ear canal inserts)

Leather footwear

AN = as needed

AR = as required

SR = selection is required

Training

  • Training is required for all employees that may be exposed to an electrical hazard. Their training must include the following subjects:

    • Specific hazards associated with electrical energy

    • Safety-related work practices that will provide protection from job-specific electrical hazards

    • Identifying and understanding the relationship between electrical hazards and associated injuries

  • In addition to the training listed above, all qualified persons will receive training on the following subjects:

    • Constructing and operating electrical equipment

    • Identifying and avoiding electrical hazards

    • Becoming familiar with electrical policies and procedures, PPE, insulating and shielding materials, insulated tools, and test equipment

    • Selecting an appropriate test instrument and demonstrating how to use the device to verify the absence of voltage

  • Employees permitted to work within the limited-approach boundary (three to five feet from the energized equipment) will receive additional training to do the following:

    • Distinguish between exposed energized electrical conductors and other parts

    • Determine nominal voltage of exposed, energized electrical conductors

    • Understand the approach distances

    • Understand the decision-making process necessary to do the following:

      • Perform the job-safety planning

      • Identify electrical hazards

      • Assess the associated risk

      • Select the appropriate risk-control methods

  • Training can be done in the classroom, on the job, or a combination of the two.

  • Employees exposed to shock hazards must be trained at least annually about how to safely release victims from contact with exposed, energized electrical conductors or circuit parts.

  • Verify at least annually that required training has been completed and documented. Training documents must be maintained for the duration of the employee’s employment.

  • Tasks that are performed less often than once per year will require retraining each year.

  • Supervisors should verify at least annually that employees are complying with the safety-related work practices in these guidelines.

  • Retrain employees every three years if any of the following conditions exist:

    • Employees are not complying with these guidelines.

    • There is new technology.

    • Procedures change.

    • An employee performs work not normally done during his or her regular job duties.

Energized Electrical Work Permit

  • A permit is required when work is performed within the restricted-approach boundary (approximately one foot from the electrical equipment).

  • A permit is not required under any of the following conditions if a qualified person uses the PPE required by the label:

    • Equipment testing and troubleshooting

    • Thermography and visual inspections

    • Other nonelectrical tasks performed outside the restricted-approach boundary (staying at least one foot away from the electrical equipment)

  • The Energized Electrical Work Permit will include the following:

    • Description and location of the electrical equipment to be worked on

    • Justification for why the work must be performed energized

    • Description of the safe work practices to be followed

    • Results of shock and arc-flash risk assessment:

      • Nominal voltage to which personnel will be exposed

      • Limited-approach boundary distance

      • Restricted-approach boundary distance

      • Shock and arc-flash PPE to be used during the work activity

    • Types of barricades to be used to keep unqualified persons away

    • Evidence that a job briefing occurred

    • Signatures from management that approve energized work

Personal Protective Equipment

Employees working in areas where electrical hazards are present must be provided with and must use protective equipment that is designed and constructed for the specific part of the body to be protected and for the work to be performed.

When an employee is working within the arc-flash boundary (including testing and troubleshooting), all parts of the body must be protected using PPE. Use table 2 to find the PPE required. In addition to the PPE listed in table 2, any employee working within the restricted-approach boundary must also wear rubber insulating gloves rated for the voltage the gloves will be exposed to.

Employees will use insulated tools or handling equipment when working inside a restricted-approach boundary of exposed, energized electrical conductors where tools or handling equipment might make accidental contact.

All PPE and tools must be inspected before each use for contamination or damage.

Responsibilities of Host Employer and Contractor

Before electrical work begins, a documented meeting between the host employer and contractor must be held to ensure that all parties understand the requirement of these electrical safety guidelines.

Host Employer’s Responsibilities

  • Inform the contractor of known electrical hazards related to the contractor’s work.

  • Share electrical installation information related to the contractor’s work.

  • Observe the contract employees while they work, and report any violations of these standards to the contract supervisor.

Contractor’s Responsibilities

  • Instruct all contract employees on information and hazards shared by the host employer.

  • Instruct all contract employees on the requirements of these electrical safety guidelines, and ensure the guidelines are followed.

  • Tell the host employer of any unique electrical hazards identified during the project.

  • Report back to the host employer any measures taken to correct violations reported by the host employer.