brantmacga
Señor Member
- Location
- Georgia
- Occupation
- Former Child
Restaurant, 1000/3 service, 208Y/120.
Square D I-Line MDP w/ 8 225A QOB panelboards. AP-1 through 6, LP-1 Lighting, CP-1 Computer (POS) panel. Also an EP-1 panel that's mounted inside a table. I'm going to attach a pic to give a reference of the layout. All of the AP panels are in a modular panelboard assembly. The LP & CP panels are separate, but they don't have any GFCI's.
There are approximately 60+ 20/1 GFCI circuit breakers, 10+ 20/2 & 30/2 GFCI circuit breakers, and 14x 50/3 GFCI circuit breakers. This store has been open for maybe 8-10/wks. I've been told that "almost" every GFCI circuit breaker within the AP panels except for the 50/3 breakers has tripped. There is no pattern; some days they might have no breaker trip, some days 4-5, and days like today where 12 breakers tripped.
Some of the 20/2 breakers that have tripped are 208v circuits. The 50/3 are all 208v circuits, and as I said none of those breakers have ever tripped, but I wanted to mention that the 50/3 breakers have no connection point for a load neutral wire. They are rated at 208v only.
Almost all of the circuits that have tripped are in EMT conduit; a couple that have tripped are in PVC through the slab landed in a steel box. I have not been on-site to troubleshoot. I've sent a couple of people down but none were able to determine anything. I spoke w/ an engineer at the utility's PQ division, and was told as far as they can tell, nothing is wrong on their end.
I've never experienced anything like this; here are my thoughts so far. I'm writing them out for help thinking this over.
A) Is it possible there is a neutral/ground bond somewhere downstream of the MCB that is causing this? Troubleshooting would involve shutting down the site in the middle of the night and check each circuit grounded conductor for a N/G bond. Why would it affect all circuits and not the circuit w/ the downstream bond? Why wouldn't it trip that breaker immediately every time? Why would it affect 208v circuits?
B) Is it possible leakage current from a piece of equipment is causing this? How am I going to find that if its not constant?
C) Is it possible I have a damaged conductor somewhere that is putting voltage on the neutral and causing this? Like in the mV range; but again why not the 50/3 breakers?
I'm having a lot of trouble wrapping my head around why the 20/2 208v circuits are also tripping.... where is that current going and why isn't it causing a dead-short? Why is it NOT affecting the 50/3 breakers? The only difference between these CB's and the 20/2 - 30/2's is the lack of a load-neutral connection.
Square D I-Line MDP w/ 8 225A QOB panelboards. AP-1 through 6, LP-1 Lighting, CP-1 Computer (POS) panel. Also an EP-1 panel that's mounted inside a table. I'm going to attach a pic to give a reference of the layout. All of the AP panels are in a modular panelboard assembly. The LP & CP panels are separate, but they don't have any GFCI's.
There are approximately 60+ 20/1 GFCI circuit breakers, 10+ 20/2 & 30/2 GFCI circuit breakers, and 14x 50/3 GFCI circuit breakers. This store has been open for maybe 8-10/wks. I've been told that "almost" every GFCI circuit breaker within the AP panels except for the 50/3 breakers has tripped. There is no pattern; some days they might have no breaker trip, some days 4-5, and days like today where 12 breakers tripped.
Some of the 20/2 breakers that have tripped are 208v circuits. The 50/3 are all 208v circuits, and as I said none of those breakers have ever tripped, but I wanted to mention that the 50/3 breakers have no connection point for a load neutral wire. They are rated at 208v only.
Almost all of the circuits that have tripped are in EMT conduit; a couple that have tripped are in PVC through the slab landed in a steel box. I have not been on-site to troubleshoot. I've sent a couple of people down but none were able to determine anything. I spoke w/ an engineer at the utility's PQ division, and was told as far as they can tell, nothing is wrong on their end.
I've never experienced anything like this; here are my thoughts so far. I'm writing them out for help thinking this over.
A) Is it possible there is a neutral/ground bond somewhere downstream of the MCB that is causing this? Troubleshooting would involve shutting down the site in the middle of the night and check each circuit grounded conductor for a N/G bond. Why would it affect all circuits and not the circuit w/ the downstream bond? Why wouldn't it trip that breaker immediately every time? Why would it affect 208v circuits?
B) Is it possible leakage current from a piece of equipment is causing this? How am I going to find that if its not constant?
C) Is it possible I have a damaged conductor somewhere that is putting voltage on the neutral and causing this? Like in the mV range; but again why not the 50/3 breakers?
I'm having a lot of trouble wrapping my head around why the 20/2 208v circuits are also tripping.... where is that current going and why isn't it causing a dead-short? Why is it NOT affecting the 50/3 breakers? The only difference between these CB's and the 20/2 - 30/2's is the lack of a load-neutral connection.
