Lockout Tagout for Branch Circuit Work
Purpose
Two claims get confused on almost every branch circuit job, and the confusion is what puts hands on a live conductor. The first is that a breaker is open. The second is that the conductor you are about to strip is dead. They are not the same claim, they are not proved by the same act, and only the second one matters.
This exists because a panel directory is a hypothesis written by somebody else, because a device box routinely holds conductors from more than one circuit, and because a shared neutral stays hot with return current after its own breaker is open. Shops that reserve the full sequence for switchgear build the habit of skipping it on 15 A circuits, which is where the volume is and therefore where the exposure is.
One citation fork matters first. 29 CFR 1910.147 excludes exposure to electrical hazards from work on conductors and equipment in electric utilization installations at its own (a)(1)(ii)(C), so it is not the standard here. For general industry the controlling practice is 29 CFR 1910.333(b)(2); on construction sites it is 29 CFR 1926.417. The live-dead-live proving sequence is in neither; it is NFPA 70E-2021, 120.5.
Scope
Covers de-energizing and verifying branch circuits and feeders in dwellings and light commercial buildings at 50 V to 600 V nominal, where the shop controls the disconnecting means.
Does not cover the decision to work energized instead, which the energized work permit SOP owns, or PPE selection, which the arc flash SOP produces as values consumed here. It also does not cover mechanical stored energy such as a spring-charged mechanism or a compressor, which falls under 29 CFR 1910.147 proper.
Roles and responsibilities
| Role | Owns | Hands off |
|---|---|---|
| Technician at the point of work | Steps 1 through 10 and their own lock | Never hands their lock to anyone; it leaves with the person who set it |
| Second tech or helper | Their own lock, and the load check at step 3 | Reports what did and did not go dead in specific words, not "it's off" |
| Supervising master | Any tag-only condition and any expansion of isolation | Records why a circuit could not be isolated so the estimator sees it |
| Customer or occupant | What may be shut off and for how long | Names loads that must not drop unwarned: a sump, a freezer, a medical device |
Procedure
Set the boundary, dress from the pre-entry record, and write on the ticket that the directory is unverified. Acceptance: the panel is accessible with working clearance clear, panel-entry PPE is on, and nobody without a qualification basis is inside the marked boundary. Wrong looks like a helper at the open panel in a t-shirt. Stop rule: clear the space before the deadfront comes off or work does not start. Hazard: opening a deadfront is itself an energized task, so the arc-rated layer and class-rated gloves go on before the screws move.
Inventory every source that can energize the point of work, not just the one on the directory. Acceptance: a written list naming the suspected breaker, any second circuit sharing the box, any multiwire partner, and every backfeed source on the premises: a generator with an interlock or transfer switch, a PV inverter, a battery system, a UPS, a low-voltage transformer, and any subpanel fed from a different service. Wrong looks like a list with one line on it. Stop rule: if the premises has PV or a generator and you cannot confirm its disconnect state, find it before opening anything. Hazard: a PV array is energized by daylight and its DC conductors stay live with the AC disconnect open, so covering the array is not an isolation method.
Open the disconnecting means for every source, and confirm the load actually dropped. Acceptance: for each source, a load you can see or hear goes off and someone says which one. Wrong looks like a breaker that moves to OFF while the receptacle keeps working, meaning the handle is broken internally or the directory pointed at the wrong device. Stop rule: a breaker that does not drop its load is a defective disconnecting means; isolate upstream or red-tag it and re-scope. Hazard: a molded case breaker can fail with contacts welded closed, and handle position then tells you nothing.
Apply one lock and one tag per person at every disconnecting means. Acceptance: a lockout attachment physically prevents the handle returning to ON, each tech has their own lock on it, and the tag carries a name, a date and a callback number. Wrong looks like tape and a folded note. Stop rule: where a panel cannot accept a lockout device, the cover goes on and gets locked, or a supervising master approves a documented tag-only condition with a person posted at the panel throughout. Hazard: the event this prevents is another trade re-energizing the circuit to test their own work, most often during an occupied fit-out.
Verify the test instrument on a known live source of the same nominal voltage. Acceptance: the meter reads within its stated accuracy on a known live circuit, on the same function and range you are about to use. Wrong looks like a meter reading zero on a circuit you know is live, meaning a blown fuse, a dead battery or a broken lead. Stop rule: an instrument that fails the check is swapped, not tried again. Hazard: this check happens on a live circuit at arm's length with gloves on, never on the conductor you are trying to prove dead.
Test for absence of voltage at the point of work, on every conductor and combination, including ones you did not come for. Acceptance: zero volts from each ungrounded conductor to every other ungrounded conductor, to the grounded conductor, and to ground, the sequence NFPA 70E-2021 120.5 requires. Every conductor in the box gets tested, not only the pair on the device. Wrong looks like a single probe on the target receptacle's screws. Stop rule: any reading above zero, on any conductor in the enclosure, sends you back to step 2 with a new source to find. Hazard: a non-contact tester is not an absence-of-voltage test at any voltage; it cannot see a conductor behind another conductor and gives no reading for a broken lead.
Re-verify the instrument on the known live source before accepting the dead reading. Acceptance: the meter reads correctly on the known source again, after the zero readings, which is what makes those zeros mean anything. Wrong looks like a meter that failed between the two checks, making every zero worthless. Stop rule: a failed second check voids the verification; swap the meter and repeat step 6 in full. Hazard: OSHA's before-and-after instrument check at 1910.333(b)(2)(iv)(B) is written for circuits over 600 V nominal, so at 120/240 V the requirement comes from NFPA 70E-2021 120.5 and from ordinary competence; do it anyway.
Prove and manage the grounded conductor before you open it. Acceptance: the white conductor reads zero volts to ground and is confirmed carrying no current with a clamp meter before separation, and where it serves a multiwire branch circuit, both ungrounded conductors are open and locked. Wrong looks like a white wire that sparks when the connector comes off. Stop rule: current on a neutral you were about to open means a second circuit is still energized on that shared neutral; return to step 3. Hazard: opening a loaded shared neutral puts the full return current through whatever bridges the gap, and at the point of work that is the technician.
PANEL KITCHEN DEVICE BOX
breaker 14 (leg A) -- black ---- upper receptacle
breaker 16 (leg B) -- red ------ lower receptacle
neutral bar -------- white ----+- upper neutral
(shared) +- lower neutral
Open breaker 14 alone and the white still
carries breaker 16's return current.
NEC 210.4(B) requires a simultaneous
disconnect for both, which is what makes
one handle tie the correct lockout point.
Maintain continuous possession of the work area, and re-test after any break. Acceptance: the tech does not leave the point of work with conductors exposed, and if the area was left for any reason, steps 5 through 7 are repeated in full before touching anything. Wrong looks like resuming after lunch on the strength of a lock still being in place. Stop rule: any break in possession voids the verification, with no judgment call about how long it was. Hazard: another trade may have added a splice, or an occupant may have plugged a generator into a receptacle on the same circuit, backfeeding through the locked breaker.
Release in order and confirm the restoration. Acceptance: conductors landed and torqued, box made up, cover on, tools and people accounted for, then each person removes their own lock, then the breaker is closed and the circuit tested for correct polarity, correct grounding and correct device operation. Wrong looks like a lock removed by someone other than its owner. Stop rule: a lock whose owner has left the site is not cut without a supervising master present and a written entry; that control is what keeps a lock meaningful. Hazard: re-energizing is a switching operation into a circuit just worked on, done with the cover on and the body out of line with the panel face.
The record this produces
One isolation record per circuit per visit, on the ticket. Fields: panel and circuit identification as found and as corrected, the step 2 source list with each item marked open or not applicable, lock owners and times, the meter and its verification results before and after, the actual readings at the point of work including conductors that were not the target, any expansion of isolation and why, and the restoration test results.
The directory correction has the longest life. Almost every older panel carries a directory that is partly fiction, and a shop that records the correction and updates the panel legend converts a recurring hazard into a one-time fix. The estimator reads the expansion-of-isolation entries, because a site whose boxes routinely hold two circuits needs diagnostic time in the bid. After an event, the step 6 readings are the only evidence the verification happened at the point of work rather than at the panel.
Worked pass: kitchen receptacle replacement, 1990s two-story dwelling
Ticket is to replace a damaged 20 A kitchen receptacle. The directory says circuit 14, "kitchen."
Step 2 lists breaker 14, a possible multiwire partner since the kitchen shows two receptacle circuits, no PV, no generator, and a low-voltage doorbell transformer elsewhere. Step 3 opens breaker 14 and the upper half of the target receptacle dies while a plug-in radio in the adjacent receptacle keeps playing, which is the first useful fact. Breaker 16 is opened and the radio stops. Step 4 puts two locks on a two-pole lockout device, one from the lead tech and one from the helper.
Step 5 verifies the meter on a live dining room receptacle at 121 V.
Step 6 fails. The target receptacle proves at zero volts on every combination, but a switch leg in the same box that nobody came for reads 118 V to ground. The stop rule fires: that is not a marginal reading to explain away, it is a live conductor inside the enclosure the tech's hands are about to enter. Work stops with the cover off and the boundary still marked.
Back at step 2, the switch leg traces to breaker 22, an under-cabinet lighting circuit added years after the house was built and never entered in the directory. Breaker 22 is opened, the under-cabinet lights are confirmed dead, both techs add locks, and step 6 runs again from the top. This time every conductor in the box reads zero on every combination.
Step 7 re-verifies the meter at 121 V on the same dining room receptacle. Step 8 clamps the white conductor at 0.0 A before separating it, confirming the multiwire partner is genuinely open rather than merely quiet.
Restoration at step 10 found correct polarity and a bootleg ground on the old device, recorded as its own finding rather than silently reproduced. The panel legend was corrected for circuits 14, 16 and 22, and the ticket carries the correction so the next visit starts from a true document.
References
- 29 CFR 1910.333(b)(2), the controlling work practice for de-energized electrical utilization work in general industry, and 29 CFR 1910.147(a)(1)(ii)(C), the carve-out that sends it there
- 29 CFR 1926.417, lockout and tagging of circuits, the construction-scope counterpart under Subpart K
- NFPA 70E-2021, 120.5, the process for establishing and verifying an electrically safe work condition, in the edition your electrical safety program has adopted
- NEC (NFPA 70) 210.4(B), simultaneous disconnect for multiwire branch circuits, and Article 690 for photovoltaic disconnecting means
- See related: the arc flash boundary and PPE selection SOP, and the energized work permit SOP