Parallel Breakers

[carloslt]

Hello,
I have been an electrician for about 5 years and two days ago, I found an interesting circuit breakers configuration and I want to know if is acceptable. I found "two breakers in parallel". Two, 165 amp breakers protecting two, 2/0 conductors in parallel going to the same terminal block to feed a chiller. two conductors in parallel is not new for me, but the two breakers are. I am asking because I was not aware of this condition, the equipment was no longer used, and the breakers were "off". When I was tracing the the wires to use that branch for something else, I turned "on" one breaker, finding that the second breaker ("off") was fed back thru the terminal block. It seems to me like an "unsafe condition". This equipment has been disconnected for more than a decade. Thanks.

 

[infinity]

Do you have any photo's of this equipment?

 

[RD35]

Yes photos would help! I've never heard of a 165A breaker....definitely not a standard size. Did you mean to type "175"? Are the breakers 3-pole? We need more information.

 

[Ainsley Whyte]

Hello,
I have been an electrician for about 5 years and two days ago, I found an interesting circuit breakers configuration and I want to know if is acceptable. I found "two breakers in parallel". Two, 165 amp breakers protecting two, 2/0 conductors in parallel going to the same terminal block to feed a chiller. two conductors in parallel is not new for me, but the two breakers are. I am asking because I was not aware of this condition, the equipment was no longer used, and the breakers were "off". When I was tracing the the wires to use that branch for something else, I turned "on" one breaker, finding that the second breaker ("off") was fed back thru the terminal block. It seems to me like an "unsafe condition". This equipment has been disconnected for more than a decade. Thanks.

send a photo

 

[Ainsley Whyte]

Hello,
I have been an electrician for about 5 years and two days ago, I found an interesting circuit breakers configuration and I want to know if is acceptable. I found "two breakers in parallel". Two, 165 amp breakers protecting two, 2/0 conductors in parallel going to the same terminal block to feed a chiller. two conductors in parallel is not new for me, but the two breakers are. I am asking because I was not aware of this condition, the equipment was no longer used, and the breakers were "off". When I was tracing the the wires to use that branch for something else, I turned "on" one breaker, finding that the second breaker ("off") was fed back thru the terminal block. It seems to me like an "unsafe condition". This equipment has been disconnected for more than a decade. Thanks.

the two breaker are in the same panel with two different wires to the same load ?

 

[Jraef]

Unless the two breakers are mechanically linked so that they both open together, that installation was not to code and should never have been done. People do dumb things sometimes, or out of desperation, do something “temporary” and then never go back to fix it. You found one.

 

[charlie b]

I agree with Jraef. Specifically, I believe this would be a violation of 240.8.

 

[Jraef]

I agree with Jraef. Specifically, I believe this would be a violation of 240.8.

Thank you. Couldn't find it on my phone but I knew it was there...

 

[iceworm]

I have never seen one, but the code does not disallow

240.8 Fuses or Circuit Breakers in Parallel. Fuses and circuit
breakers shall be permitted to be connected in parallel where
they are factory assembled in parallel and listed as a unit. Individual
fuses, circuit breakers, or combinations thereof shall not
otherwise be connected in parallel.

 

[packersparky]

I have never seen one, but the code does not disallow

240.8 Fuses or Circuit Breakers in Parallel. Fuses and circuit
breakers shall be permitted to be connected in parallel where
they are factory assembled in parallel and listed as a unit. Individual
fuses, circuit breakers, or combinations thereof shall not
otherwise be connected in parallel.

A better example.