New building service from and exsisting adjacent building

[J.D.D.]

I am currently in the design of a new auxiliary boiler shed in NJ. The plan is to feed the new shed from a new 480v, 3ph, 4w, 250A C.B. from an existing MCC in an adjacent building on the owner's property (i do not believe the MCC is the service entrance for the existing buidling). The owner requested that the new feed to come inside the shed, go through an unfused disconnect switch and into a wire trough. From there, four fused disc sw's will tap out of the wire trough to feed the various loads (the unfused disc sw, wire trough, and 4 disc sw's will all be mounted adjacently). My question is whether or not the unfused disconnect switch must have overcurrent protection? Electrically, the feed to the shed is protected from the MCC in the adjacent building. However, NEC 230.91 states "the service overcurrent device shall be an integral part of the service disconnecting means or shall be loctaed immediately adjacent thereto." The NEC defines "service" as, "the conductors and equipment for delivering electric engergy from the serving utility to the wiring system of the premises served" so does 230.91 even apply? if the feed is coming from a point within the system and not directly form a utility?

Secondly, would the neutral and ground need to be bonded at the unfused disconnect switch? Once again, electrically, the system neutral and ground are already bonded at the existing service entrance in the existing building. It is my understanding that the neutral would come into an isolated ground block in the unfused disc sw, and i would just need to provide a gec to a new ground rod at the shed.

 

[Dennis Alwon]

You really need to be reading art. 225 esp. part II. 225.31 states a means for disconnecting all ungrounded conductors that supply or pass thru the building shall be provided. 225.32 states the disco shall be nearest the point of entrance of the conductors.

 

[david]

Leave your line isolation device (unfused disconnect) on the outside of the shed. It won?t qualify as a service disconnect but nothing says it cannot be on the outside. Enter the shed and provide the required disconnect(s)