400A Main turns off by itself

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Hello. I have an extremely unusual situation occurring in a recently wired building and I'm at my wits end with trying to figure this out.

It is a 400A 3phase jawed meter UG service supplying power to a coffee joint. The facility was up and running flawlessly for 2 months, then I started getting calls saying multiple GFI circuits would trip simultaneously. SO on our first response call looking into this, as we were standing there, the main 400A breaker turned itself off. It did not trip, it simply turned off. Upon calling Square D and them reassuring me it cannot happen, I've since changed that main breaker 3 times as each one did the same thing.

I had also received authorization to remove all GFI circuit breakers and only install GFI receptacles where they were necessary/required by code. And I still have the same issue where, while the building is up and running, multiple 120v/208v circuit breakers (normal CB's not GFI CB's) will trip simultaneously followed by the main a short while later will simply again turn itself off. Please note all the branch 120v circuits were installed with separate neutrals. There is also no rhyme or reason to when these trips happen. Not one specific piece of equipment that turns on or off will cause this, so trying to time when it happens is impossible. It can be fine for 12 hours or it can be fine for 10 minutes.

I have recorded amperage/voltages prior to these outages and have determined no power spikes/surges of any kind. The utility company has been out 3 different times to test their side and has assured me everything on their end is correct. My next step is to tear this building apart completely, but before I do, I was hoping to get some feedback from anyone who has had something similar. Any help/advise would be greatly appreciated. thank you!
 

mgookin

Senior Member
Location
Fort Myers, FL
Hello. I have an extremely unusual situation occurring in a recently wired building and I'm at my wits end with trying to figure this out.

It is a 400A 3phase jawed meter UG service supplying power to a coffee joint. The facility was up and running flawlessly for 2 months, then I started getting calls saying multiple GFI circuits would trip simultaneously. SO on our first response call looking into this, as we were standing there, the main 400A breaker turned itself off. It did not trip, it simply turned off. Upon calling Square D and them reassuring me it cannot happen, I've since changed that main breaker 3 times as each one did the same thing.

I had also received authorization to remove all GFI circuit breakers and only install GFI receptacles where they were necessary/required by code. And I still have the same issue where, while the building is up and running, multiple 120v/208v circuit breakers (normal CB's not GFI CB's) will trip simultaneously followed by the main a short while later will simply again turn itself off. Please note all the branch 120v circuits were installed with separate neutrals. There is also no rhyme or reason to when these trips happen. Not one specific piece of equipment that turns on or off will cause this, so trying to time when it happens is impossible. It can be fine for 12 hours or it can be fine for 10 minutes.

I have recorded amperage/voltages prior to these outages and have determined no power spikes/surges of any kind. The utility company has been out 3 different times to test their side and has assured me everything on their end is correct. My next step is to tear this building apart completely, but before I do, I was hoping to get some feedback from anyone who has had something similar. Any help/advise would be greatly appreciated. thank you!
Were you just on site or were you actually standing in front of the panel such that you are certain another person did not open that breaker?
 

brian john

Senior Member
Location
Leesburg, VA
I have been involved in 3 jobs where this was happening and ALL of the causes were solved by a hidden camera. One job had a disgruntled ex-employee with keys, one had a disgruntled current employee coming in at all times and turning off the CB, the last one had an assistant manager hoping the manager would be fired.

On the assistant manager job they spent $1000's trying to figure out the cause. I was suspicious early on but management including the assistant manager would not believe an employee would be doing this. When we hid the camera we only told the manager and asked him to keep quite.
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
I have been involved in 3 jobs where this was happening and ALL of the causes were solved by a hidden camera. One job had a disgruntled ex-employee with keys, one had a disgruntled current employee coming in at all times and turning off the CB, the last one had an assistant manager hoping the manager would be fired.

On the assistant manager job they spent $1000's trying to figure out the cause. I was suspicious early on but management including the assistant manager would not believe an employee would be doing this. When we hid the camera we only told the manager and asked him to keep quite.
+1 on this. i'd hide a gopro somewhere on time lapse, every five seconds or so,
high enough resolution to clearly be able to identify the person, and the biggest
flash card that will fit in there. and i'd not tell anyone i was doing it.
 

GerryB

Senior Member
Were you just on site or were you actually standing in front of the panel such that you are certain another person did not open that breaker?
Good point. There was a post a while back about many breakers turning themselves off, (not tripping). I think it was a recently done residence. The post went on a while, lots of questions and I don't think the OP ever gave an answer.
 

augie47

Moderator
Staff member
Location
Tennessee
To clarify, the breaker handle is actually moving to the "off" position or power simply goes off ??
What steps are taken to restore power ?
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Forgive my skepticism but I don't see any other explanation.

If it had been only one breaker that was doing this and replacing it solved it I would agree it could have been a malfunctioning breaker.
But since OP said the main had been changed three times and other breakers are doing it, I don't see any way of this happening short of someone physically turning them off.
 

Cow

Senior Member
Location
Eastern Oregon
If you're 100% sure it's not physically being turned off, then it sounds like it's time to rent or buy a good power logger with a fast sample rate and stick it on the service to see if you can catch any events.
 
To clarify- the handle is moved to the off position, they don't trip on OC?
If that's the case, IMHO there's a human or other animal involved.

Do you have a plot of which breakers go off when and what the normal load is? Who's working at the time?
Does the panel have a door? Open or closed? Is it where someone can easily brush the handles (although the concept of "accidentally brushing the handle" of a 400a breaker seems flawed)?

So....
Hide your own camera.
Lock the panel or the breakers.
Don't lock the panel but put up a "DO NOT OPEN" sign on it and a hair or something caught in the door. If the hair isn't there next time, somebody opened the door.
It's more work, but... install maybe six new breakers and move three existing loads to them; leave the old breakers w/o load. See which ones go off.
 

Pizza

Senior Member
Location
Minnesota
400A Main turns off by itself

Do you have sensitivity settings on the main breaker?
Does the main breaker have GFI protection?
Do you just really like coffee and you won't figure it out on purpose to keep drinking coffee?

Ditch the main breaker and put a 400 amp fused disconnect right next to it.

Sent from my iPhone using Tapatalk
 
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kwired

Electron manager
Location
NE Nebraska
Maybe try putting a LOTO attachment on it, but lock it on? If someone is turning it off they will have to remove this to do so, it will still trip on overload though - but should leave handle it in the mid position if tripped not the full off position.

If breaker has magnetic trip adjustment make sure it is not too low - but that too should leave breaker in the tripped mid position if activated.
 
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