Bad Circuit breaker?

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flywright52

flywright52

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Missouri
I work almost exclusively in residential, so I thought I would ask those of you with more experience this question. I am helping my church with a problem in a 3 phase branch to a pump house used for watering the soccer field. One leg of the 3 phase (480) is missing. I checked the voltage at the circuit breaker feeding the pump house and found 480 only between two legs (yellow-brown) and ~240 between the suspect leg (orange) and the other two (good) legs. I disconnected the wires from the breaker and checked for continuity on each pole. I got a short in two of the poles when the breaker was switched ON and open when OFF. The suspect leg indicated open in either the on or off position. I know this is a rookie question, but is there any other test I need to do before replacing the (expensive) breaker? I have attached a picture of the breaker.
 

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No, but I opened the main breaker and the 2 pole breaker feeding the only other branch out of the box. I thought that would isolate the busses at that point.
 
Since this is a GE breaker, here is a true story.

I was working on a new power plant. We were connecting some pumps to breakers in a control room. One of the pumps wouldn't come on, and I traced the problem to a brand new GE breaker. We couldn't fool with the installed equipment without getting an OK from one of the GE engineers. He came out to the control room and I told him my story. He went over to the suspect breaker and slammed the handle on and off HARD about four times and left it in the on position. He said 'Try it now'. We did, and the pump came on just like it was supposed to.

'You have to do that to them sometimes', he said as he was getting ready to leave.
 
K8MHZ said:
Since this is a GE breaker, here is a true story.

I was working on a new power plant. We were connecting some pumps to breakers in a control room. One of the pumps wouldn't come on, and I traced the problem to a brand new GE breaker. We couldn't fool with the installed equipment without getting an OK from one of the GE engineers. He came out to the control room and I told him my story. He went over to the suspect breaker and slammed the handle on and off HARD about four times and left it in the on position. He said 'Try it now'. We did, and the pump came on just like it was supposed to.

'You have to do that to them sometimes', he said as he was getting ready to leave.
Click to expand...

Thanks, I'll try that before I pull the breaker.

73's
Flywright52
 
Sometimes bugs crawl into the breaker or debris falls in there when under initial construction and gets in between the contacts when they are open, then they form a resistance when closed that shows as a voltage drop. Given the spider webs on that left pole, I'd guess that momma spider put her egg sac in there one day when the breaker was off. Exercising the breaker by opening and closing it a few times either knocks the debris out or, if under load, the arc vaporizes it. If the resistance remains after trying that, the contacts have been damaged beyond recovery.

If you have a "short" between phases inside of the breaker, you would know it by virtue of the pool of molten metal and burned plastic. There is no way voltage can jump phase-to-phase on the inside without severe and noticeable physical damage.
 
Jraef said:
............................................

If you have a "short" between phases inside of the breaker, you would know it by virtue of the pool of molten metal and burned plastic. There is no way voltage can jump phase-to-phase on the inside without severe and noticeable physical damage.
Click to expand...

:D
 
Donate to church??

Donate to church??

whenever a deacon or repairman of fellow contractor asks for materials ,, I usually donate them....

If have to buy it for them, then it is full price, But , if it is a "leftover" or "tear-out" or an "extra"
, they are welcome to it


I have dissembled many scrap breakers, just to see what is inside,

remove breaker from panel , open the covers and look inside.... be careful...
 
Did this ever work? I've seen those breakers installed with a screw missing into the panel bus on one phase.
 
infinity said:
Did this ever work? I've seen those breakers installed with a screw missing into the panel bus on one phase.
Click to expand...

Yes, it did work. We were just checking out the sprinkler system before the summer season and found the problem. The installation was added to the church about 10 years ago.

I'm going tomorrow to pull the breaker and examine it more closely before ordering a replacement. Thanks to everyone for their input.
 
That is a higher AIC rated breaker. Be careful to get a new breaker with the required AIC.
 
I haven't had to do it on larger frame breakers like in the OP but have done it a few times with smaller plug on breakers - is to remove the breaker blow compressed air through the arc ventilation openings and sometimes blow a few bugs out of the breaker that were interfering with contact operation and then they worked again.


Also AFAIK most breakers not only close the contacts when you move the handle to the on position but also do so with a "wiping action" that helps clean contact surface to some degree and is why cycling the handle a couple times sometimes makes them work again.
 
Might want to take a look at the transformer make sure you're not dealing with a corner grounded delta. It's been a long time since I worked on one but I do remember they give you some strange readings.if that were the case the breaker could be good and you could be dealing with failed equip. Just a thought.
 
K8MHZ said:
Since this is a GE breaker, here is a true story.

I was working on a new power plant. We were connecting some pumps to breakers in a control room. One of the pumps wouldn't come on, and I traced the problem to a brand new GE breaker. We couldn't fool with the installed equipment without getting an OK from one of the GE engineers. He came out to the control room and I told him my story. He went over to the suspect breaker and slammed the handle on and off HARD about four times and left it in the on position. He said 'Try it now'. We did, and the pump came on just like it was supposed to.

'You have to do that to them sometimes', he said as he was getting ready to leave.
Click to expand...


I would not leave a breaker like that in place mainly because I would not trust it to trip according to specs.
 
Dennis Alwon said:
I would not leave a breaker like that in place mainly because I would not trust it to trip according to specs.
Click to expand...

I had no choice. This was in a PECC (Portable Electrical Control Center) built by GE for a new power plant. Anything done in the PECCs had to be approved by a GE engineer. Replacement wasn't approved or considered. It was wham bam, thank you ma'am and once the pump was running, all was good with Vendor GE.
 
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