Bad Circuit breaker?

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Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
Your post is a bit confusing to me. I would make sure the load is off and disconnect the wires from under the breaker and turn it on. Test the breaker.... It does sound like a bad breaker but other things you stated had me confused :)
 
kwired

kwired

Electron manager
Location
NE Nebraska
VTW said:
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.
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I don't believe it is corner grounded. One leg would read zero to ground (or very close to zero) but you would have full 480 volts between all three and 480 to ground on the ungrounded legs.

OP did not state whether or not he checked voltage on supply side of breaker, which would help us out some, but did check continuity through each pole and did seem to find open circuit in one pole.


With 240 volts readings from two leads to another it possibly even could be a system with midpoint of one phase grounded - such system would have 240 volts to ground on two phases and a high leg of 416 volts. If that is what it is then it is possible the high leg is lost line and maybe even faulted to ground which would leave you reading 240 to the other two legs. Textbook case would be a break in high leg conductor of an underground run.
 
S

SCelectrician

Member
Location
Goose Creek, SC USA
I work for a school district and GE breakers are absolutely garbage. If you ever want side money from your church I would recommend a change out to a Cutler Hammer (Eaton) panelboard. You indeed have a bad breaker that needs to be replaced without a doubt. An OL on the meter ON or OFF is a sure fire issue. Don't knock the Fluke meter, either. It's my weapon of choice.

To the GE rep that slammed the breaker on and off several times....what a joke..hahaha I would have been dying laughing in his face! Thanks for the story!
 
M

meternerd

Senior Member
Location
Athol, ID
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retired water & electric utility electrician, meter/relay tech
Is the incoming side of the breaker showing 480 between all phases? What to ground? Have you tried turning the red plastic "trip" test? If it trips with the test, reset it and trip it a few times. Could be one phase isn't resetting. Just a comment....if you're working with hot 480, especially on the line side of a breaker, be VERY careful and wear PPE. Arcs don't care if you're helping out a church and you know what the Bible says...."THOU SHALT NOT TEST THE LORD THY GOD!":)
 
S

SCelectrician

Member
Location
Goose Creek, SC USA
Dennis Alwon said:
Your post is a bit confusing to me. I would make sure the load is off and disconnect the wires from under the breaker and turn it on. Test the breaker.... It does sound like a bad breaker but other things you stated had me confused :)
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He said he disconnected the wires and checked each phase for continuity. At least that's my understanding of what he wrote. :lol:
 
S

SCelectrician

Member
Location
Goose Creek, SC USA
meternerd said:
Is the incoming side of the breaker showing 480 between all phases? What to ground? Have you tried turning the red plastic "trip" test? If it trips with the test, reset it and trip it a few times. Could be one phase isn't resetting. Just a comment....if you're working with hot 480, especially on the line side of a breaker, be VERY careful and wear PPE. Arcs don't care if you're helping out a church and you know what the Bible says...."THOU SHALT NOT TEST THE LORD THY GOD!":)
Click to expand...

I do agree with testing the incoming side of the breaker, but unless the damage was exclusively to that one side of the spine. The breaker across on the same phase would also have an issue. Or if a leg was lost, several things would be having issues. However, I agree 100% with testing the incoming power side.
 
Sierrasparky

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
meternerd said:
Is the incoming side of the breaker showing 480 between all phases? What to ground? Have you tried turning the red plastic "trip" test? If it trips with the test, reset it and trip it a few times. Could be one phase isn't resetting. Just a comment....if you're working with hot 480, especially on the line side of a breaker, be VERY careful and wear PPE. Arcs don't care if you're helping out a church and you know what the Bible says...."THOU SHALT NOT TEST THE LORD THY GOD!":)
Click to expand...

Don't think that is a test. it is probably a trip sensitivity adjustment.
 
kwired

kwired

Electron manager
Location
NE Nebraska
SCelectrician said:
I do agree with testing the incoming side of the breaker, but unless the damage was exclusively to that one side of the spine. The breaker across on the same phase would also have an issue. Or if a leg was lost, several things would be having issues. However, I agree 100% with testing the incoming power side.
Click to expand...
OP later mentioned that there was only one other two pole breaker in same panelboard. If it happened to not be using the lost leg - there wouldn't be any other things not working. Still doesn't quite make sense where the 240 volts measured come from unless it is a high leg system and the high leg is open but also has a ground fault. I'm still putting my money on that possibility more so then anything else, at least with no more detail then we have so far.

Would really be nice to know what voltage measurements were on line side of the breaker, as well as measurements to neutral if present as well as to ground if separate from neutral.
 
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