2.4 Electrical work has its own lockout rule

1 Which rule applies to which job

The dividing line is the hazard you are protecting against, not the trade you belong to. If the danger is that the machine might move, you are in 1910.147. If the danger is that a conductor might shock or arc, you are in 1910.333(b). A single job can be both: pulling a motor is a mechanical isolation problem and an electrical one, and the answer is to satisfy both paragraphs rather than to pick one.

Note 2 to 1910.333(b)(2) makes that dual compliance explicit and cheap: "Lockout and tagging procedures that comply with paragraphs (c) through (f) of § 1910.147 will also be deemed to comply with paragraph (b)(2) of this section provided that: (1) The procedures address the electrical safety hazards covered by this Subpart; and (2) The procedures also incorporate the requirements of paragraphs (b)(2)(iii)(D) and (b)(2)(iv)(B) of this section."

Read that as a checklist for your plant's program. A 1910.147 procedure is accepted for electrical work if it covers the electrical hazards and adds two specific things: the additional safety measure that must accompany a tag used without a lock, and the requirement to test with instruments for induced voltage and backfeed. If your procedure is silent on either, it is not sufficient for the work.

2 Lock and tag, on each disconnecting means

This is the biggest single difference and it surprises people who learned lockout on the production floor. 1910.333(b)(2)(iii)(A): "A lock and a tag shall be placed on each disconnecting means used to deenergize circuits and equipment on which work is to be performed," with two exceptions, "and the lock shall be attached so as to prevent persons from operating the disconnecting means unless they resort to undue force or the use of tools." (B) adds that each tag "shall contain a statement prohibiting unauthorized operation of the disconnecting means and removal of the tag."

So the default in Subpart S is both devices, not either one. The two exceptions are narrow and worth knowing precisely.

Every other case is a lock and a tag. And (b)(2)(i) adds a paperwork requirement that has no equivalent in 1910.147: "The employer shall maintain a written copy of the procedures outlined in paragraph (b)(2) and shall make it available for inspection by employees" — with a Note that says the written procedures "may be in the form of a copy of paragraph (b) of this section." The regulation itself, printed and available, satisfies the requirement.

3 Deenergize first — and the three notes about when you may not

1910.333(a)(1) states the hierarchy: "Live parts to which an employee may be exposed shall be deenergized before the employee works on or near them, unless the employer can demonstrate that deenergizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. Live parts that operate at less than 50 volts to ground need not be deenergized if there will be no increased exposure to electrical burns or to explosion due to electric arcs."

The three notes underneath it are where the arguments actually happen, and they are narrower than most people assume. Note 1's examples of increased or additional hazards: "interruption of life support equipment, deactivation of emergency alarm systems, shutdown of hazardous location ventilation equipment, or removal of illumination for an area." Note 2's examples of infeasibility: "testing of electric circuits that can only be performed with the circuit energized and work on circuits that form an integral part of a continuous industrial process in a chemical plant that would otherwise need to be completely shut down in order to permit work on one circuit or piece of equipment."

Two things are not on those lists: production schedule and inconvenience. "We can't take the line down this week" is not one of OSHA's examples, and the burden is on the employer to demonstrate the exception, not on the technician to disprove it.

Where energized work is genuinely justified, 1910.333(c)(2) limits who may do it: "Only qualified persons may work on electric circuit parts or equipment that have not been deenergized under the procedures of paragraph (b) of this section. Such persons shall be capable of working safely on energized circuits and shall be familiar with the proper use of special precautionary techniques, personal protective equipment, insulating and shielding materials, and insulated tools." The arc flash analysis, the incident energy and the PPE selection that go with that work live in NFPA 70E, a copyrighted consensus standard that this course names and does not reproduce.

4 Reenergizing: four requirements, in the order given

1910.333(b)(2)(v) is a second ordered sequence, and it applies "before circuits or equipment are reenergized, even temporarily."

1. 1
   (A) A qualified person conducts tests and visual inspections, as necessary, to verify that all tools, electrical jumpers, shorts, grounds and other such devices have been removed, so that the circuits and equipment can be safely energized.
2. 2
   (B) Employees exposed to the hazards associated with reenergizing the circuit or equipment are warned to stay clear.
3. 3
   (C) Each lock and tag is removed by the employee who applied it or under his or her direct supervision — with a narrow exception when that employee is absent from the workplace.
4. 4
   (D) There is a visual determination that all employees are clear of the circuits and equipment.

Step (A) is the one that catches maintenance crews: temporary grounds and jumpers installed to make the work safe become a short circuit the moment power returns. And (C)'s exception has two conditions in it, both on the employer: ensure the employee who applied the device is not available at the workplace, and ensure that employee is aware the device has been removed before resuming work there.

One more paragraph belongs to this moment and sits in a different section. 1910.334(b)(2): "After a circuit is deenergized by a circuit protective device, the circuit may not be manually reenergized until it has been determined that the equipment and circuit can be safely energized. The repetitive manual reclosing of circuit breakers or reenergizing circuits through replaced fuses is prohibited." A Note carves out the case where the design shows the operation was caused by an overload rather than a fault. Resetting a breaker to see whether it holds is the practice this paragraph exists to stop.

5 Cord-connected tools and the plug in your pocket

1910.147(a)(2)(iii)(A) puts cord and plug connected equipment outside the hazardous energy standard when exposure is "controlled by the unplugging of the equipment from the energy source and by the plug being under the exclusive control of the employee performing the servicing or maintenance." Both halves. A cord lying on the floor beside its receptacle is not exclusive control; the plug in your pocket, in a lockout bag, or behind a locked cover is.

The daily reality of cords is governed by 1910.334(a). (a)(2)(i) requires portable cord- and plug-connected equipment and flexible cord sets to be "visually inspected before use on any shift for external defects (such as loose parts, deformed and missing pins, or damage to outer jacket or insulation) and for evidence of possible internal damage (such as pinched or crushed outer jacket)" — with an exemption for equipment that stays connected in place and is not exposed to damage until it is relocated. (a)(2)(ii): a defect or evidence of damage means the item is removed from service until repairs and tests render it safe.

• (a)(1): cords may not be used to raise or lower equipment, and may not be stapled or hung in a way that could damage the jacket or insulation.
• (a)(3)(ii)-(iii): plugs and receptacles may not be connected or altered in a way that breaks the continuity of the equipment grounding conductor, and adapters that interrupt the grounding connection may not be used.
• (a)(4): portable equipment and cords used in highly conductive locations — inundated with water or other conductive liquids — shall be approved for those locations.
• (a)(5)(i): hands may not be wet when plugging and unplugging cords and equipment, if energized equipment is involved.

6 The tools and the shields

1910.335 is short and every line of it is aimed at maintenance work. (a)(1)(i) requires employees in areas with potential electrical hazards to be provided with and to use electrical protective equipment appropriate for the parts of the body to be protected and for the work performed. (a)(1)(ii) requires that equipment to be maintained in a safe, reliable condition and periodically inspected or tested as required by 1910.137. (a)(1)(iv) and (v) require nonconductive head protection wherever there is a danger of head injury from electric shock or burns, and eye or face protection wherever there is danger from electric arcs, flashes, or flying objects resulting from electrical explosion.

(a)(2)(i) covers the tools: "When working near exposed energized conductors or circuit parts, each employee shall use insulated tools or handling equipment if the tools or handling equipment might make contact with such conductors or parts." (A) adds fuse handling equipment insulated for the circuit voltage when the fuse terminals are energized; (B) requires ropes and handlines used near exposed energized parts to be nonconductive.

And (a)(2)(ii) contains the sentence a mechanic should read twice, because it describes the state a panel is in for most of a maintenance job: "When normally enclosed live parts are exposed for maintenance or repair, they shall be guarded to protect unqualified persons from contact with the live parts." An open panel door in a plant aisle is an exposure for everybody who walks past it, and the barrier, the barricade or the attendant of (b)(1) through (b)(3) is part of the job rather than an extra.