Circuit Breaker tripping...not sure why...

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iwire said:
So you watched the meter for 3 hours straight on each of those loads. ;)
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yeah...i'm still watching..:D

unless MH fixtures draw less after they are on for awhile, i'll stick with my original story;)
 
emahler said:
i don't believe there was a fault...i believe that there was an overload condition...remember phase A was reading 184A...the rated continuous load for these breakers are 180A...

i just found it interesting that there were multiple branch circuits with continuous loads of over 16A....one of them with a continuous load of 21.5A...on a 20A CB....
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Fault meaning semi-instant OL, that's why I asked about new additional loads on circuit.
 
emahler said:
i don't believe there was a fault...i believe that there was an overload condition...
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Only believe what you can measure and document. Starting with an assumption, while often helpful, can sometimes lead you down the garden path. Since this is happening so frequently now, put a recorder on it and settle the matter once and for all.
 
mdshunk said:
Only believe what you can measure and document. Starting with an assumption, while often helpful, can sometimes lead you down the garden path. Since this is happening so frequently now, put a recorder on it and settle the matter once and for all.
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that's the next step...was just hoping to tap the minds of some more smarter people..:D
 
emahler said:
newest added load was about 3 yrs ago...
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breaker might be getting weaker due to the load being over 80% for years. we just recently had a 20 amp 277 volt breaker in a lighting panel trip that had a load of 19.8 amps and it was fine for a few years then recently it started to trip over and over
 
emahler said:
yeah...i'm still watching..:D

unless MH fixtures draw less after they are on for awhile, i'll stick with my original story;)
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When is the last time they were relamped, ballast...etc?

3 yrs ago?
 
celtic said:
Does the lighting ckt/s cause the MDP to dump?
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? not sure I follow...

All the lighting circuit run through lighting contactors and are controlled by an energy management system...

no particular circuit causes the mdp to trip...is that what you are asking?
 
Main tripping

Main tripping

Is there a ground fault relay on the main and what is the voltage on the smaller 20 amp breakers??? Does the main have an adjustable trip?? they are usually shipped in the lowest setting>..
 
You had mentioned some CBs in #1 and then some MH fixtures in #21.
I'm wondering if the CB's were for those MHs(and the relamping/reballasting timeframe).

We had an interesting situation a few years back with some site lighting....you name it went wrong....from wrong taps to GF situations to fixtures exploding....the MDP 1/4 mile away was tripping ~ through multiple OCPDs that did NOT trip.
 
Hello Erik , and by the way, would it be possible to rig up a fused disco at the front end for a temporary bypass to see if there really is a problem other than mr. main breaker? (Dear code guru's, this is just a random thought, I have not given it much consideration to see if such an adventure would violate one of the many hundreds of codes it probably would). Most shops like how mine used to be have at least a doz. fused s/s cans and a bunch of fuses laying around the back room someplace. Fuses can blow faster than breakers given the right choice, and therefore a safe test done on the main feeders.
 
quogueelectric said:
Is there a ground fault relay on the main and what is the voltage on the smaller 20 amp breakers??? Does the main have an adjustable trip?? they are usually shipped in the lowest setting>..
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it's not the main that's tripping (2000A, and yes it is GFI)...it's the 225A breaker in the MDP that's tripping...
 
celtic said:
You had mentioned some CBs in #1 and then some MH fixtures in #21.
I'm wondering if the CB's were for those MHs(and the relamping/reballasting timeframe).

We had an interesting situation a few years back with some site lighting....you name it went wrong....from wrong taps to GF situations to fixtures exploding....the MDP 1/4 mile away was tripping ~ through multiple OCPDs that did NOT trip.
Click to expand...

yeah, i have an issue at the airport where a ballast is tripping a 30A 2P 480V circuit...the fixtures are 1000W 480V...fun...

but in this case, a little more background...there was an addition to the building about 3 yrs ago. Approximately 100 - 400W MH fixtures were added to this panel. No problems...

About a year ago, the entire building was relamped with new 400W MH lamps...approx 450-500

there were no other loads added to this panel since the addition. since the relamp there has been no other major lighting maintenance done.

All circuits in the panel can be energized...there are no ballasts/fixtures out...they all light up and operate....
 
macmikeman said:
Hello Erik , and by the way, would it be possible to rig up a fused disco at the front end for a temporary bypass to see if there really is a problem other than mr. main breaker? (Dear code guru's, this is just a random thought, I have not given it much consideration to see if such an adventure would violate one of the many hundreds of codes it probably would). Most shops like how mine used to be have at least a doz. fused s/s cans and a bunch of fuses laying around the back room someplace. Fuses can blow faster than breakers given the right choice, and therefore a safe test done on the main feeders.
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not really an option...
 
Just a thought.
It is possible that there is a high resistance ground fault path. With all of the maintenance that has occurred, a fault condition has occurred. High resistance fault current paths can take days to trip a breaker.

Was there any maintenance work performed shortly before this all occurred?
 
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