NEC Service entrance question
NEC Service entrance question
(OP)
Our customer decided at the last minute to put in a transfer switch (manual-really a contactor), non service entrance rated (no overcurrent protection). They want to put it in after the service transformer and metering but before the disconnect. I have researched this and there seems to be some confusion in interpreting 230.82 and 230.94. From an engineering standpoint, the manual transfer switch is not protected since the overcurrent protection is after it. Based on this alone, makes this idea bad in my opinion. However, I believe the utility has cut-outs on the primary of their transformer.
In any case, is this configuration allowed by the NEC? Is it allowed since the transfer switch is UL listed and part of the requirement to maintain the listing is to provide OC protection?
Any help would be appreciated. Sorry if I posted in the wrong area. Thank you!
In any case, is this configuration allowed by the NEC? Is it allowed since the transfer switch is UL listed and part of the requirement to maintain the listing is to provide OC protection?
Any help would be appreciated. Sorry if I posted in the wrong area. Thank you!






RE: NEC Service entrance question
in NEC art. 230.94[for instance a fire pump protected separately according to art.695]
RE: NEC Service entrance question
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: NEC Service entrance question
under 230.94, exception 1, it says the service switch shall be permitted to be on the supply side. yes this is a switch but it is not a service rated switch. Is this what they mean? the transfer switch won't be tied to any life safety or fire controls.
we use switchgear rated as service entrance equipment but also use the 6 disconnect rule so it's not as easy as just putting it after a 'disconnect' since each of the 6 switches are only rated 800A and our service is 3000A - same as mobile generator.
So what I am hearing is supporting my conclusion that it is not okay by NEC.
RE: NEC Service entrance question
RE: NEC Service entrance question
Our electrician was using some sections of part II of art 240.21(B) feeder taps, to approve the configuration of non service entrance rated transfer switch. However, 240.3 says this is not applicable, correct?
If 240.21 applies to service entrances, then would 240.21(B) Feeder Taps apply? it says conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as specified in 240.21(B)(1) through (B)(5). I wrestle with the idea that my transfer switch would be a feeder - to me its a service entrance so none of 240.21(B) would apply.
Sorry to beat a dead horse but my boss won't leave this alone and I want to make sure there are no exceptions I have overlooked. This is a new company I work for and they said they have done this lots of times, even with electrical inspections.
Thanks to all for the advice.
RE: NEC Service entrance question
Bill
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"Why not the best?"
Jimmy Carter
RE: NEC Service entrance question