That new controller retrofit last month nearly burned a job down

We pulled an old Otis unit out of a building near downtown Cleveland back in May. The customer wanted a new MCE controller and we had it all wired up by Thursday. Friday morning came and the doors started cycling randomly, car would go to the top floor and just sit there. Took me 12 hours over the weekend to find a ground fault in the main drive cable that wasn't showing up on my meter. Come Monday, a junior guy on the crew plugged a temporary light into the controller cabinet and almost got cooked when the short finally let go. The factory wiring diagrams had the phase rotation labeled backwards from what was actually on site. Has anyone else run into MCE boards that show phantom faults after a swap like this?

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evan_morgan815mo ago

Ground bond test is step one, but MCE boards are known for throwing ghost faults when the phase rotation doesn't match what's in the manual. You sure you didn't swap two wires on the input side before that junior guy got zapped?

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anthony_lane555mo ago

Phantom faults after a swap" happens when you skip the ground bond check, man. Gotta meter the cabinet first.

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