Electrical work practices

Yes — live parts that an employee may be exposed to must be deenergized before work unless deenergizing creates a greater hazard or is infeasible. The rule 1910.333(a)(1) requires deenergizing whenever practical and mandates that any alternative safety-related work practices be consistent with the electrical hazards present.

• If deenergizing would increase hazards (for example, interrupting life-support or critical ventilation) or is infeasible due to equipment design, employers must use other protective measures as described in 1910.333(a)(2).

Energized parts may be worked on only when deenergizing would create additional hazards or is infeasible, and then the employer must provide safety-related work practices that prevent direct or indirect contact with the energized parts. See 1910.333(a)(2).

• Those work practices must protect employees from contacting energized parts directly with their body or indirectly through conductive objects and must be suitable for the voltage and conditions involved.
• When feasible, prefer deenergizing and follow the deenergized procedures in 1910.333(b).

No — parts operating at less than 50 volts to ground need not be deenergized if there is no increased risk of electric burns or arc-explosion hazards. 1910.333(a)(2) allows this exception.

• Even when under 50 volts, if work or the environment could increase exposure (for example, moist conditions or flammable atmospheres), deenergizing or other protective measures should be used.

No — control circuit devices may not be used as the sole means for deenergizing circuits or equipment. 1910.333(b)(2)(ii)(B) explicitly prohibits relying solely on devices such as push buttons, selector switches, or interlocks to deenergize equipment.

• Employers must disconnect the circuits from all electric energy sources using disconnecting means that isolate the energy source.

You must release or safely control stored electrical energy that could endanger personnel (for example, discharge capacitors and short/ground high capacitance elements). 1910.333(b)(2)(ii)(C) requires this.

• If you handle capacitors or associated equipment while discharging them, treat them as energized until they are safely discharged and grounded.

A lock and a tag must be placed on each disconnecting means used to deenergize circuits and equipment unless specific exceptions apply, and each tag must prohibit unauthorized operation or removal. See 1910.333(b)(2)(iii)(A) and 1910.333(b)(2)(iii)(B).

• Locks must prevent operation except by undue force or tools; tags must clearly state that unauthorized operation or removal is prohibited.

You may use a tag without a lock only if a lock cannot be applied or the employer demonstrates that tagging provides an equivalent level of safety, and you must add at least one additional safety measure (for example, removing an isolating circuit element or blocking a controlling switch). See 1910.333(b)(2)(iii)(C) and 1910.333(b)(2)(iii)(D).

• Document the alternative measures in procedures and ensure they truly prevent reenergization or access equivalent to a lockout.

A lock may be placed without a tag only if a single circuit or piece of equipment is deenergized, the lockout does not extend beyond the work shift, and employees exposed to reenergizing hazards are familiar with the procedure. See 1910.333(b)(2)(iii)(E).

• This is a limited condition; if multiple circuits or extended lockouts are involved, both lock and tag are required.

A qualified person must both operate controls (or otherwise verify the equipment cannot be restarted) and use test equipment to confirm circuits and parts are deenergized, checking for backfeed or induced voltages. See 1910.333(b)(2)(iv)(A) and 1910.333(b)(2)(iv)(B).

• If testing circuits over 600 volts nominal, ensure the test equipment is checked immediately before and after the test to verify proper operation.

Each lock and tag must be removed by the employee who applied it or under that employee's direct supervision; if that employee is absent from the workplace, a qualified person designated by the employer may remove it provided the employer ensures the original employee is not available and is informed before returning to work. See 1910.333(b)(2)(v)(C) and 1910.333(b)(2)(v)(C)(1)-(2).

• Employers must also make a visual determination that all employees are clear of circuits and equipment before reenergizing (1910.333(b)(2)(v)(D)).

Only qualified persons may work on energized circuit parts or equipment that have not been deenergized, and they must be able to work safely on energized circuits using appropriate techniques, PPE, insulating materials, and insulated tools. See 1910.333(c)(2).

• "Qualified" means the person has training and knowledge to recognize hazards and the means to avoid them; unqualified persons must not perform this work.

An unqualified person working in an elevated position must keep at least 10 feet (305 cm) from any unguarded energized overhead line up to 50 kV. See 1910.333(c)(3)(i)(A)(1).

• For voltages over 50 kV, add 4 inches (10 cm) for every 10 kV over 50 kV per 1910.333(c)(3)(i)(A)(2).

Qualified employees must not approach exposed energized parts closer than the minimum approach distances in Table S-5 unless they are insulated from the energized part, the energized part is insulated from other conductors and the person, or the person is insulated from other conductive objects. See 1910.333(c)(3)(ii) and Table S-5 in 1910.333(c)(3)(ii)(C).

• For example, for over 750 V but not over 2 kV, the minimum approach distance is 1 ft. 6 in. (46 cm), per Table S-5.

Vehicles or equipment capable of elevating parts near overhead lines must be operated to maintain a 10 ft. (305 cm) clearance; for voltages over 50 kV increase clearance 4 in. for every 10 kV above 50 kV. The clearance may be reduced if the structure is lowered in transit, if rated insulating barriers are used (not attached to the vehicle), or if an insulated aerial lift is used by a qualified person following Table S-5. See 1910.333(c)(3)(iii)(A)-(3).

• Special care is required when equipment is intentionally grounded near overhead lines because hazardous ground potentials may exist (1910.333(c)(3)(iii)(C)).

No — employees may not enter spaces with exposed energized parts unless lighting enables them to perform the work safely, and they may not perform tasks near energized parts if lack of illumination or obstructions prevent observation of the work. See 1910.333(c)(4)(i)-(ii).

• Employees must not reach blindly into areas that may contain energized parts.

When working in confined or enclosed spaces with exposed energized parts, employers must provide—and employees must use—protective shields, barriers, or insulating materials to prevent inadvertent contact; doors and panels must be secured to prevent swinging into employees. See 1910.333(c)(5).

• Ensure all barriers and guards are adequate for the voltage and conditions present.

Portable ladders used where the employee or ladder could contact exposed energized parts must have nonconductive siderails. See 1910.333(c)(7).

• Nonconductive ladders reduce the risk of creating a conductive path to the worker and are required whenever contact with live parts is a possibility.

No — conductive articles like metal jewelry, watch bands, and conductive-threaded clothing may not be worn if they might contact exposed energized parts unless they are rendered nonconductive by covering, wrapping, or other insulating means. See 1910.333(c)(8).

• Employers should enforce removal or insulating of such items before employees enter energized work areas.

Only a qualified person following the requirements of paragraph (c) may temporarily defeat an electrical safety interlock, and the interlock system must be returned to operable condition when the work is completed. See 1910.333(c)(10).

• Defeating an interlock is allowed only for temporary work by qualified personnel and always with the intent to restore the protective system afterward.

OSHA allows temporary removal of lockout/tagout devices and re-energization only when necessary to test or position machines, but employers must provide employee protection and follow a defined sequence of actions before re-energizing as required by 1910.147(f)(1). See OSHA's letter of interpretation on the minor servicing exception ([Original URL: https://www.osha.gov/laws-regs/standardinterpretations/2024-10-21]) and 1910.147(f)(1).

• Required steps include clearing tools/materials, removing employees from danger areas, removing LOTO devices as specified, energizing only for the limited testing or positioning with effective protection, then deenergizing and reapplying energy control measures if further servicing is needed. The OSHA interpretation emphasizes that the temporary energization sequence must maintain employee protection at all times.