Multiple XFMRs fed from a single C.B and single feeder.

[liverpool]

Reviewing a design in progress. Can multiple transformers be fed from a single circuit breaker using a single feeder?

i.e. Two 5KVA single phase XFMRs (480-120/240V) both fed via a single 2P-30Amp C.B. Single primary feeder taps the primary lugs of XFMR 1 and continues to tap primary lugs of XFMr 2. Anything wrong in th scenario above? If so, I'd appreciate the NEC reference.

 

[augie47]

Short answer is "yes". As long as you comply with the values in 450.3(B).
In this case you would need to assure the secondary OCP does not exceed 125% of the transformer current.

Some may disagree with my next comment. In your case, 250% of the primary current is 26 amps. My read on 450.3(B) is that there is no provision for "next larger size" when applying the 250% rule, so I feel your primary OCP would need to be 25 amps, not 30.

 

[liverpool]

Found the answer in NEC 450.7. Thanks,

 

[steve66]

Found the answer in NEC 450.7. Thanks,

450.7 is for parallel transformers, which would also have the secondaries tied together. It doesn't sound like this is what you have.

Anyhow, I completely agree with Augie and don't see any problem with a single feeder.

 

[don_resqcapt19]

Found the answer in NEC 450.7. Thanks,

Not sure that section applies. To me operating in parallel means that the secondaries are tied together and I don't think that is the case for your application.