SERIES RATING EXISTING SYSTEM

[shaneo]

Ok, so I have a good friend who has installed a 125A MLO rated subpanel (cutler hammer) fed from a Siemens 200A load center MLO which is fuse protected at the MSB (also Siemens). My question is this...in a typical situation like this (for siries rating) the 125A rated subpanel should have a main breaker installed instead of a MLO rated at the 200A breaker that is feeding the 200A MLO load center but since the 200A MLO is protected from fuses would he still have to install a Main Breaker in the 125A subpanel? Whew, that was a lot sorry. Am I assuming this correctly? I'm not really sure why he didn't just install the same manufacture brand...thanks in advance

 

[shaneo]

SERIES RATING EXISTING SYSTEM

OK, SO I HAVE MY ANSWER...THE 200A CLASS T FUSES THAT PROTECT THE 200A MLO COVERS THE SERIES RATING TO THE 200A MLO LOAD CENTER AND ANYTHING AFTER THAT ATTACHES TO THE BRANCH CIRCUITRY. ALTHOUGH THE 125A RATED SUBPANEL STILL SHOULD HAVE BEEN A SIEMENS BRAND SO THAT THERE WOULD BE NO CONFUSION ESPECIALLY IF THERE WERE EVER AN ELECTRICAL "ISSUE" IN THE FUTURE WITH ANYTHING. THE ONLY REQUIREMENTS ARE THAT THERE BE A SERIES RATING STICKER ON THE 200A LOAD CENTER STATING THAT IT SERIES RATES BACK TO THE MSB 200A 300V CLASS T 100,000 AIC FUSES.

 

[cowboyjwc]

Darn, that's what I was gonna say.

 

[templdl]

Ok, so I have a good friend who has installed a 125A MLO rated subpanel (cutler hammer) fed from a Siemens 200A load center MLO which is fuse protected at the MSB (also Siemens). My question is this...in a typical situation like this (for siries rating) the 125A rated subpanel should have a main breaker installed instead of a MLO rated at the 200A breaker that is feeding the 200A MLO load center but since the 200A MLO is protected from fuses would he still have to install a Main Breaker in the 125A subpanel? Whew, that was a lot sorry. Am I assuming this correctly? I'm not really sure why he didn't just install the same manufacture brand...thanks in advance

It must be noted that any OCPDs must be UL listed to be series rated with other OCPDs. You can get fuses that are current limiting but they must be proven to protect devices down stream. All breakers hae a degree of current limiting, some more than others. As with fuses specific breakers must be tested and proven with OCPDs that are down stream to protect them. Eaton electrical (cutler-Hammer) does have a Consulting Application Guide that combines Eaton breakers that are series rated with one another as well as fuses. I'm sure that SqD has something similar. But what I don't think that you will find is one manufacturer of breakers being series rated with others.
The key word is UL listed for a series rating.