Locked out, but the meter reads 48 V

Transfer conveyor, drive end: motor junction box on a shared conduit run · 8 min

The transfer conveyor is locked out and tagged for a gearbox swap: your lock is on the disconnect handle and the millwrights are waiting. The verify-dead check stops everything. The meter reads 48 V AC on a motor lead that should be at zero. Nobody touches the gearbox until you can say where the 48 V comes from and whether it can push current.

Actions

Probes

Each probe reports what you’d actually observe on the machine. Some readings fit more than one cause. That’s the job.

Diagnosis

Prove you are on the right disconnect first. Walk it down, check the tag, and look at the blade. Then explain the reading.

Which cause do you commit to?Ghost voltage from a coupled run: Capacitive coupling from an energized circuit sharing the conduit run, holding up a potential with no current behind it.Backfeed through interlock wiring: A foreign 48 V interlock circuit from another panel landing in the junction box, fed from a supply this disconnect never touches.A broken meter lead: An intermittent conductor inside the molded plug, leaving the meter input floating and displaying a wandering number.

Help

Try to work it out from the machine first. That is how the skill builds.

Lists the checks you have not used yet. This one costs nothing: your attempt can still count as a clean solve.

Shows the evidence that rules out the wrong causes. Marks your attempt as assisted.

Shows the root cause. The attempt stops counting toward your course.

Event log

Nothing yet. Try an action. There is no penalty for a wrong move.