But not in the module? Hummm... The three big ones are usually in the module:
1) Shorted snubber,
2) Loss of isolation between SCR and frame,
3) Loss of isolation between choke windings and frame.
Outside of that, most "flash" problems resulting in a short have to do with foreign objects (Screws, hardware) finding there way to the wrong spot.
I am assuming you made that reading with the load removed as a cold load will often read as close to a short.
We swapped the modules, and had the same issue, so determined it was not an issue with the module.
That reading was made with a module in place, but the breakers tripped.
So even with the breakers off, you read continuity between hot and ground at the female pin connector? Not that I'm advocation you do this, but it could be a suggestion to your "qualified individual." I would, with the breakers off and/or module removed, open the pin connector and check all connections there. Then Lock-Out/Tag-Out both racks. Could be right where the pigtail enters the raceway, or just inside. Work my way back toward the dimmer rack, checking every junction box, and lifting the downstream connections from the terminal strips. Is this a raceway fed with multi-cable or flex conduit? Highly unlikely you'll get all the way back to the backplane of the rack before finding the problem....The conclusion, after reading continuity between hot and ground off the ol' DMM, from the raceway, is a dead-short, somewhere between the raceway and the module...
So even with the breakers off, you read continuity between hot and ground at the female pin connector? Not that I'm advocation you do this, but it could be a suggestion to your "qualified individual." I would, with the breakers off and/or module removed, open the pin connector and check all connections there. Then Lock-Out/Tag-Out both racks. Could be right where the pigtail enters the raceway, or just inside. Work my way back toward the dimmer rack, checking every junction box, and lifting the downstream connections from the terminal strips. Is this a raceway fed with multi-cable or flex conduit? Highly unlikely you'll get all the way back to the backplane of the rack before finding the problem.
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