Feeder loading 1

[thinker]

Dear colleagues,
We need to connect a 800 kVA transformer (480/480)to user grid. The available single busplug is sized for approximately a half of transformer FLA. Is it possible and/or legal to use 2 busplugs to feed a transformer via 2 parallel branches (assuming their equal length)?

 

[wareagle]

My question would be are the bus plugs physically close together. If so you could bring the conductors into a fused disconnect switch and on to the transformer. The fuse would be size for the transformer per 450.3(B). The scondary would be protected per 240.21C.

 

[thinker]

I would like to clarify my question: I am talking about 2 fusible busplug tap-offs which in sum provide needed ampacity, can I feed a single load (transformer) from 2 parralel and protected (?)branches?

 

[mpparent]

I don't see a section in the code (NEC) that prohibits it, but it may not be the best practice.

Mike

 

[alehman]

Not according to the NEC.

Article 240: "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."

 

[thinker]

Alehman,
Thanks for very good reference.