1.2 What 1910.147 covers — and what it does not

1 The five industries the standard leaves out

1910.147(a)(1)(ii) lists five categories the standard does not cover. They are worth knowing precisely, because each one is governed somewhere else rather than nowhere at all.

Exclusion (D) causes the most confusion in a manufacturing plant, because most plants do plenty of electrical work. The line is this: when you are servicing a machine and electricity is one of the energy sources you have to control, you are under 1910.147. When the work itself is electrical work on the utilization installation — pulling a motor starter, working in a panel, terminating a feeder — 1910.333(b)(2) governs, and it adds a requirement 1910.147 does not have: an instrument test of the conductors. Part 3, Chapter 2 and Part 4, Chapter 4 both come back to this.

2 Production versus servicing, and the door between them

1910.147(a)(2)(ii) states that normal production operations are not covered by the standard, and then immediately opens a door: servicing or maintenance that takes place during normal production operations is covered if either of two things is true.

1. A
   An employee is required to remove or bypass a guard or other safety device; or
2. B
   An employee is required to place any part of the body into an area on the machine where work is performed on the material being processed (the point of operation), or where an associated danger zone exists during a machine operating cycle.

This is the paragraph that decides the argument about clearing jams, wiping down rollers, picking a dropped part out of a chute, or reaching into a wrapper to free a film. If the hand goes past the guard, or into the point of operation, or into a danger zone that exists during the cycle, the work has walked through the door and 1910.147 applies to it.

3 The minor servicing exception, and how it is misused

Attached to (a)(2)(ii) is a note that has probably been stretched further than any other sentence in the standard. It reads: minor tool changes and adjustments, and other minor servicing activities, which take place during normal production operations, are not covered by this standard if they are routine, repetitive, and integral to the use of the equipment for production, provided that the work is performed using alternative measures which provide effective protection.

Four conditions, all of them at once:

The fourth condition is the one that gets dropped. "Alternative measures which provide effective protection" means something real: a two-hand control that cannot be tied down, an interlock that cannot be defeated and drops power, a light curtain that stops the cycle, a positively driven guard, a hold-to-run device. It does not mean training, a warning sign, a rule about being careful, or the operator's experience. If the only thing standing between a hand and the point of operation is a decision, the exception has not been met and the machine needs to be locked out.

4 Cord-and-plug equipment

1910.147(a)(2)(iii)(A) removes from the standard "work on cord and plug connected electric equipment for which exposure to the hazards of unexpected energization or start up of the equipment 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."

Two conditions again, and the second is where it usually falls apart. Exclusive control means the plug is in the technician's sight, in their hand, in their pocket, or behind a plug lockout box that only they can open. A cord that disappears behind a machine and plugs into a receptacle on the far side of a wall is not under anyone's exclusive control — someone will plug it back in, and they will be helping.

The first condition matters too: unplugging must control the hazard. A bench grinder unplugged is safe. A cord-connected hydraulic power pack with a charged accumulator is not, because pulling the plug does nothing about the stored energy. In that case the exception does not apply and the full standard does.

5 Hot tap operations

The third exception, 1910.147(a)(2)(iii)(B), covers hot tap operations on pressurized transmission and distribution pipelines carrying gas, steam, water or petroleum products. It is available only where the employer demonstrates three things: that continuity of service is essential, that shutdown of the system is impractical, and that documented procedures are followed and special equipment is used which will provide proven effective protection for employees.

A hot tap is defined at 1910.147(b) as a procedure involving welding on a piece of equipment — pipelines, vessels or tanks — under pressure, in order to install connections or appurtenances. It is specialized work with its own engineering controls, and the exception is written narrowly enough that it cannot be borrowed for ordinary maintenance on a pressurized line. "We could not shut it down without stopping production" is not the same as "shutdown is impractical."

6 Where 1910.147 sits among other standards

1910.147(a)(3)(ii) is a short paragraph with wide consequences: when other standards in part 1910 require the use of lockout or tagout, they shall be used and supplemented by the procedural and training requirements of this section. In other words, 1910.147 is the backbone. When a permit-required confined space entry under 1910.146 calls for isolating a space, or a machine guarding requirement leads to servicing work, the energy control comes back here for its procedures, its devices and its training.

The purpose paragraph, 1910.147(a)(3)(i), states the whole thing in one sentence: the section requires employers to establish a program and use procedures for affixing appropriate lockout or tagout devices to energy isolating devices, and to otherwise disable machines or equipment, to prevent unexpected energization, startup or release of stored energy in order to prevent injury. Program, procedures, devices, and the phrase "otherwise disable" — which is where blocking a suspended ram or chocking a roll comes in.

If you take one thing from this chapter, make it this: scope questions have written answers. Before anyone argues on the floor about whether a task needs a lock, someone should be able to point at (a)(2)(ii), (a)(2)(iii) or the minor servicing note and say which one they are relying on. Most of the time, nobody can — and that is the answer.