Exposure to an unexpected electrical energy release that could result in electric shock or burns or in an explosion caused by an electric arc is covered by the Occupational Safety and Health Administration’s (OSHA’s) standard for Electrical Safety-Related Work Practices, 29 CFR 1910.333.

Sometimes, workers cannot de-energize equipment that they will be working on or near. When that happens, it’s important to take precautions to protect them from accidental contact with live electricity.

Conditions for Working Live 

For most purposes, OSHA requires that live parts be de-energized before employees begin working on or near them. OSHA permits work on or near exposed live parts only when:

  • You can demonstrate that de-energizing introduces additional or increased hazards, or
  • You can demonstrate that de-energizing is infeasible due to equipment design or operational limitations.

Safe Work Practices for Working Live

If you don’t de-energize the equipment, you’re required to comply with OSHA’s Safe Work Practices. These have to be included in your written procedures. The requirements for working on exposed live parts are found in 1910.333(c) and 1910.335. Its requirements cover:

Qualified persons. Only qualified persons may work on or near energized parts or equipment. To be considered “qualified,” workers have to be trained to work safely on energized circuits and to use special precautionary techniques, personal protective equipment (PPE), insulating and shielding materials, and insulated tools.

Work near overhead power lines. Unqualified persons who will be working near live overhead power lines must keep minimum clearance distances between themselves, any conductive equipment they are using, and the lines. For lines rated at 50 kilovolts (kVs) or less to ground, the minimum clearance distance is 10 feet; for higher voltages, workers should add 4 inches of clearance distance for every kV over 50. Qualified persons who are working inside minimum clearance distances to live overhead power lines must use insulated tools and PPE.

Vehicular and mechanical equipment. Vehicles or mechanical equipment with elevating parts that may come near overhead lines must observe the same clearance distances as personnel.

Illumination and a clear field of view. Whenever workers enter spaces containing exposed energized parts, there must be sufficient illumination for them to work safely. In addition, there must be no obstruction that prevents workers from clearly seeing the work they’re performing.

Confined or enclosed work spaces. When workers are in a confined or enclosed space (for example, a manhole or vault) that contains exposed energized parts, employees must be provided with protective shields, barriers, or insulating materials that will prevent accidental contact with these parts. If there are doors or hinged panels that could swing into the workers and push them into contact with exposed live parts, those must be secured.

Conductive materials and equipment. Sometimes, workers must handle long dimensional conductive objects (such as ducts and pipes) in areas with exposed live parts, energized conductors, or circuit parts. In such situations, you must put work practices in place (including insulation, guarding, and material-handling techniques) that will minimize the hazard.

Portable ladders. When portable ladders are used in areas where either the ladder or the worker could contact exposed, energized parts, they must have nonconductive side rails.

Clothing. Employees must not wear jewelry or clothing that could be conductive, such as watch bands, bracelets, rings, key chains, necklaces, metalized aprons, cloth with conductive thread, or metal headgear, if they might contact exposed, energized parts. It is acceptable to cover such items with insulating materials rather than removing them.

Housekeeping duties. Workers should not perform housekeeping duties in areas where they are at risk of contact with exposed live parts, unless safeguards such as insulation are put in place. In addition, they must not use electrically conductive cleaning materials (like steel wool, metalized cloth, silicon carbide, or conductive liquid solutions) close to energized parts.

Interlocks. Only a qualified person using appropriate safety equipment and safe work procedures may override an electrical safety interlock and then only temporarily while he or she is working on the equipment. When the work is finished the interlock system must be returned to its normal operation.

Special Requirements for Electrical Lockout/Tagout 

When workers will be de-energizing electrical equipment so that they can safely work on or near it, they must use lockout/tagout procedures to protect themselves from unexpected energization or startup of the equipment. But not all of OSHA’s applicable requirements are in one place.

Most lockout/tagout requirements are found in 29 CFR 1910.147, however, a few additional requirements are found in OSHA’s standard for Electrical Safety-Related Work Practices, 29 CFR 1910.333.

Electrical Lockout/Tagout

Exposed electrical parts and conductors must be de-energized before employees work on or near them. It’s not enough just to de-energize them, though; if they have not been locked or tagged out, they must be treated as if they are energized.

In order to be in compliance with all applicable lockout/tagout requirements, electrical lockout/tagout must be conducted according to both the requirements of the lockout/tagout standard (29 CFR 1910.147) and the requirements of 1910.333(b)(2)(iii)(D) and (b)(2)(iv)(B).

These requirements address:

The use of tags without locks. In situations where a lock either cannot be used, or where a tag can provide as much security for workers as the use of a lock, employees can use a tag without a lock. This is also allowed under the lockout/tagout standard, however, the electrical standard additionally requires that employers supplement that use of a tag with at least one additional safety measure in order to ensure that the level of safety provided is equivalent to that provided by a lock. Examples of additional safety measures include:

  • The removal of an isolating circuit element
  • Blocking of a controlling switch
  • Opening of an extra disconnecting device

Verification of de-energization. Before a circuit or equipment can be considered and treated as if it is de-energized, its status must be verified. The lockout/tagout standard also requires this, but the electrical standard specifies that verification must be performed by having a qualified person:

  • Try to turn on the equipment and operate it, or otherwise determine that the equipment cannot be restarted.
  • Use test equipment to test the circuit elements and electrical parts of equipment to which employees will be exposed, to verify that the circuit elements and equipment parts are de-energized. The test must determine if any inadvertently induced voltage or unrelated voltage backfeed exists in the system. If the circuit being tested is over 600 volts, the test equipment must be checked to make sure that it is operating properly immediately after use.

Written procedures

The lockout/tagout standard requires employers to document their lockout/tagout procedures. The electrical standard also requires employers to have a written copy of their lockout/tagout procedures. But here’s a piece of good news for employers: according to 1910.333, a copy of 1910.333(b) is sufficient and can be used as a “written copy” of the lockout/tagout procedure.

For more information or assistance with your Environmental and Health & Safety regulatory compliance needs, contact Ralph Carito at Total Environmental & Safety, LLC (Total) at rcarito@TotalEnviron.com or 908-442-8599.