What 1926.417 requires
29 CFR 1926.417 covers lockout and tagging of circuits in construction. Three parts:
- (a) Controls that are to be deactivated during the work must be tagged. This applies to work on energized or deenergized equipment or circuits, not only energized ones. Leaving the controls untagged is a listed common error.
- (b) Deenergized equipment or circuits must be rendered inoperative and have tags attached at all points where they can be energized.
- (c) Tags must plainly identify the equipment or circuits being worked on. A tag carrying only a worker's name does not do that.
Every point of supply
The trap in (b) is tagging one point and stopping. Picture a deenergized motor circuit that can be energized from its local disconnect and also from a transfer switch fed by a standby generator. Both supply points get tags. Tagging only the local disconnect because it is nearest, only the main service, or whichever point the electrician chooses leaves another source untagged. Tagging just one point of supply is a listed common error. Trace every source that can feed the circuit, including standby and alternate supplies, and tag each.
A lock is not specifically required
OSHA's standard interpretation letter of 2006-09-28 states that 1926.417 does not specifically require a lock. What the rule requires is that the circuit be rendered inoperative and tagged. Any method that does that is permitted, for example:
- removing a fuse or circuit element for each phase conductor
- disconnecting the conductors, including disabling plugs
The mandatory-lock idea comes from the general-industry standards 1910.147 and 1910.333, not from the construction standard. Assuming a padlock is required on every disconnect under 1926.417 is a listed common error. The rule also sets no 600-volt threshold for locks.
Tags are never optional
Using a lock does not make tags optional. Whatever method renders the circuit inoperative, 1926.417 still requires tags at all points where the circuit can be energized, and on the controls that are deactivated during the work.