Main Breaker in an Apartment tripping

Status
Not open for further replies.
P

powerplay

Senior Member
Location
In front of a computer.
I got a Service call for a Main Breaker tripping in an Apartment Suite... When she said it hsppened when her appliances were all on, and even when she only had the Heater running one night I knew it was probably just a loose connection Cutler Hammer BR2100 Breaker. I removed part of slightly discolored aluminum strands, applied antioxidant and tightened all the screws. It's for a Property Management Company. I am thinking it would be best to change the Breaker after tripping at least twice that I had heard, since I was told by the Supplier the Manufacturers only warranty breakers for one trip? .. Seems they always work in old homes again and again, but to cover all cases I guess it would be wise to change it? Thanks again for any insight!
 
Breakers of the type used in residential panels can open many times under thermal overload or handle action without damage. But one event of a bolted fault at maximum AIC level may damage it.
 
You may need to replace it. Do a voltage drop check across the breaker. Line to load of each side. IIRC, 100 mv or greater, replace it. Similar current through each conductor should give you similar VD. Remove the breaker and look for the signs of overheating on the breaker and the buss.
 
powerplay said:
I got a Service call for a Main Breaker tripping in an Apartment Suite... When she said it hsppened when her appliances were all on, and even when she only had the Heater running one night I knew it was probably just a loose connection Cutler Hammer BR2100 Breaker. I removed part of slightly discolored aluminum strands, applied antioxidant and tightened all the screws. It's for a Property Management Company. I am thinking it would be best to change the Breaker after tripping at least twice that I had heard, since I was told by the Supplier the Manufacturers only warranty breakers for one trip? .. Seems they always work in old homes again and again, but to cover all cases I guess it would be wise to change it? Thanks again for any insight!
Click to expand...

Did you pull the breaker and look at the buss bar? If the buss bar is OK, definitely replace the breaker. It's cheaper then another service call.
 
powerplay said:
...I was told by the Supplier the Manufacturers only warranty breakers for one trip? ...
Click to expand...
I have also heard this many times, and also heard claims to the contrary. Does anyone have a link to manufacturer documentation supporting or refuting such claims???
 
Smart $ said:
I have also heard this many times, and also heard claims to the contrary. Does anyone have a link to manufacturer documentation supporting or refuting such claims???
Click to expand...
Look at the UL listing/testing requirements for the type of breaker in question. That should be more authoritative and accessible than the manufacturer information in some cases.
I do recall one UL section being quoted here about one type of breaker when tested at maximum rated AIC. If I recall correctly the test required that it open once, close to normal working state and open again once. After the second opening it was acceptable that it not even reclose or that it no longer carry the rated current. The critical factor in the survival of the breaker is how large an overload it was subjected to.
But in any case if the breaker was tripping on what should not have been an overload and the terminations were not hot, then it should be replaced anyway just because it is no longer meeting specifications. An amp clamp at the panel should give you an idea of what the actual load is and whether the main and service are properly sized for that load.
 
It was an 2 pole 100 amp push in Main Breaker. Which I do not carry around in my Van. The Bus Bar appeared to be fine, and the discolored aluminum strands I removed didn't appear too bad nor spread out too far, but obviousely generated enough heat to trip the breaker. Based on what I've heard and read I am thinking that the contacts after a couple times opening in the Field in this case have likely lost some of the original approved characteristics to properly protect in an future occurence uner manufacturer's guidelines... I am planning to return after locating the Breaker to ensure I have followed up with all due diligence.
 
powerplay said:
I got a Service call for a Main Breaker tripping in an Apartment Suite... When she said it hsppened when her appliances were all on, and even when she only had the Heater running one night I knew it was probably just a loose connection Cutler Hammer BR2100 Breaker. I removed part of slightly discolored aluminum strands, applied antioxidant and tightened all the screws. It's for a Property Management Company. I am thinking it would be best to change the Breaker after tripping at least twice that I had heard, since I was told by the Supplier the Manufacturers only warranty breakers for one trip? .. Seems they always work in old homes again and again, but to cover all cases I guess it would be wise to change it? Thanks again for any insight!
Click to expand...

If you were lucky enough to be present when the breasker tripped if you attempted to latch it on reclose it were you able to latch it? If not the breaker most likely tripped on thermal where you would have to wait a bit for the thermal element to cool off before the breaker is capable of being latched and closed.
It you are able to latch the breaker shortly after the breaker tripped it most likely tripped on magnetic. If so it is never recommended to close a breaker back into a fault and must be investigated for a cause on trip and resdolved before there is an attempt to reset and close.
Persdonaslly I would opt that there is a thermal tripping issue which the others pointed out could be due to a termination issue which causes heating of the breaker which results in derating the breaker and a nuisance trip. Sinse the trip unit is close to the load end terminals I would explore the load side terminals to see if those connections have been compromised.
Since any heating at the line side terminals has to be conducted through the stationary and moving contacts is order to affect the thermal element there has to be a significant amount of heat generated to affect the thermal element. Your concern also should be abould the weakening of the contact springs whichnwoulkd cause a contact failure.
Of course should heating be as the result contact resistance itself there aslo should be a concern for weakening the contact spring(s) which escaslates the failure.
Often time using an infrared scan can be helpful in diagnosing the problem.
 
GoldDigger said:
Look at the UL listing/testing requirements for the type of breaker in question.
Click to expand...

Basically, UL489 requires molded case breakers =<100A to open and close hundreds of times at full load, They must then open and close another couple of hundred times without any load.

They are only required to open once for full bolted fault conditions, typically >10,000A, which are almost always caused by wiring errors (otherwise faults are often arcing types).
 
Status
Not open for further replies.
Top