2.1 The six steps of 1910.147(d), in the order they are written

1 The six steps, and why the order is the rule

1. 1
   (d)(1) Preparation for shutdown. Know the type and magnitude of the energy, its hazards, and the means of control — before anything is turned off.
2. 2
   (d)(2) Machine or equipment shutdown. Turn it off using the procedures established for that machine, and do it in an orderly way so the stoppage does not create a new hazard.
3. 3
   (d)(3) Machine or equipment isolation. Physically locate and operate every energy isolating device needed to isolate the machine from its energy sources.
4. 4
   (d)(4) Lockout or tagout device application. Affix a device to each isolating device, by the authorized employees, holding it in the safe or off position.
5. 5
   (d)(5) Stored energy. After the devices are on, relieve, disconnect, restrain or otherwise render safe all potentially hazardous stored or residual energy.
6. 6
   (d)(6) Verification of isolation. Before starting work, verify that isolation and deenergization have actually been accomplished.

Two places in the sequence carry all the weight. Step 5 comes after step 4 on purpose: you relieve stored energy under the protection of a lock, not before it, because bleeding an accumulator on a machine somebody can still start is a way to be hurt by two energies at once. And step 6 comes last, after everything, because verification is the only step that tests the previous five rather than performing them.

2 Step 3 is the one that requires a machine drawing

The wording of (d)(3) is worth reading closely: "All energy isolating devices that are needed to control the energy to the machine or equipment shall be physically located and operated in such a manner as to isolate the machine or equipment from the energy source(s)." Physically located. Not identified on paper, not assumed from the last time — found, with your hands on them.

This is where the definition from Part 1 does its work. The device has to be an energy isolating device under 1910.147(b): a manually operated circuit breaker, a disconnect switch, a manually operated switch that opens all ungrounded supply conductors with no pole operable independently, a line valve, a block, "and any similar device used to block or isolate energy." Not a stop button. Not a mode selector. Not a soft stop in the HMI. Not a safety relay.

3 Step 4: whose lock, and what the hardware has to be

(d)(4)(i) is one line with two requirements folded into it: "Lockout or tagout devices shall be affixed to each energy isolating device by authorized employees." Each device, and by the people doing the work. (d)(4)(ii) requires lockout devices to hold the isolating device in a safe or off position; (d)(4)(iii) requires tagout devices to clearly indicate that operating the device is prohibited, attached at the same point the lock would have gone under (A), or as close as safely possible and immediately obvious to anyone reaching for the device under (B).

The hardware requirements in (c)(5)(ii) are more specific than most people expect, and they exist because improvised hardware is how a locked-out machine gets started. Devices must be singularly identified, must be the only devices used for controlling energy, and must not be used for anything else. They must be durable for the environment and the duration. They must be standardized within the facility in at least one of color, shape or size — and for tags, print and format too. They must be substantial: a lock strong enough that removal requires excessive force or unusual techniques "such as with the use of bolt cutters or other metal cutting tools," and a tag attachment that is non-reusable, attachable by hand, self-locking, non-releasable, with "a minimum unlocking strength of no less than 50 pounds" and characteristics at least equivalent to a one-piece all-environment-tolerant nylon cable tie. And they must be identifiable: the device has to show who applied it.

(c)(5)(iii) even specifies the message: tags shall warn against hazardous conditions if the machine is energized and shall include a legend such as Do Not Start, Do Not Open, Do Not Close, Do Not Energize, Do Not Operate.

4 The eight-condition exception, and why it almost never applies

1910.147(c)(4)(i) requires procedures to be "developed, documented and utilized." A Note underneath it allows an employer to skip the documentation for a particular machine — but only when all eight of the following are true. The list is worth reading once in full, because reading it is usually enough to end the argument:

• The machine has no potential for stored or residual energy, or for reaccumulation after shutdown, that could endanger employees.
• It has a single energy source that can be readily identified and isolated.
• Isolating and locking out that source will completely deenergize and deactivate the machine.
• The machine is isolated from that source and locked out during the servicing.
• A single lockout device will achieve the locked-out condition.
• The lockout device is under the exclusive control of the authorized employee performing the work.
• The servicing does not create hazards for other employees.
• The employer has had no accidents involving unexpected activation or reenergization of that machine during servicing or maintenance.

A bench grinder on a cord may clear all eight. A machine with a pneumatic clamp, a gearbox that coasts, or a second feed does not clear the first two. And the eighth condition is retrospective: one incident on that machine closes the exception permanently.

5 Lockout is the default; tagout has to be earned

The hierarchy in (c)(2) is often stated backwards. (c)(2)(i): if a device is not capable of being locked out, the program shall use a tagout system. (c)(2)(ii): if it is capable of being locked out, the program shall use lockout — "unless the employer can demonstrate that the utilization of a tagout system will provide full employee protection as set forth in paragraph (c)(3)."

And (c)(3)(ii) says what that demonstration costs. The employer must show full compliance with all tagout-related provisions plus additional elements to reach equivalent safety, and the additional measures to be considered include "the removal of an isolating circuit element, blocking of a controlling switch, opening of an extra disconnecting device, or the removal of a valve handle to reduce the likelihood of inadvertent energization." In other words: a tag plus a physical measure that does some of the work a lock would have done.

6 The one place the sequence bends, and how

There is exactly one authorized way to interrupt the six steps mid-job, and it is written out as a five-action sequence of its own. 1910.147(f)(1) covers "situations in which lockout or tagout devices must be temporarily removed from the energy isolating device and the machine or equipment energized to test or position the machine, equipment or component thereof." Part 3, Chapter 4 works through it in full, because that is where the maintenance work actually needs it — alignment, tram, tension, a jog to seat a part.

The important thing to see now is its shape. It is not a suspension of the rules; it is a complete de-lockout and re-lockout, in miniature: clear the machine of tools and materials, remove employees from the area, remove the devices, energize and test, then deenergize and reapply the whole of paragraph (d) to continue. There is no version of it in which somebody stays inside the machine while it is energized.