Separately Derived Entrance Vs. Service Entrance

[Thomas Underwood]

There are two ways to provide electrical service to the building. Separately Derived, or Service Entrance.

At an industrial facility, or military base, the utility does not provide the transformer feeding the building many times.

Since no utility is involved, all transformers feeding each building are separately derived and require bonding of neutral to EGC to ground at either the transformer feeding the building, or the service rated transformer in the building with EGC running between the two.

Do you agree?

 

[augie47]

There are exceptions ibn 250.30 where the SDS is outside that allow you to treat it s you would a service and not have a SSBJ.

 

[electrofelon]

There are two ways to provide electrical service to the building. Separately Derived, or Service Entrance.

At an industrial facility, or military base, the utility does not provide the transformer feeding the building many times.

Since no utility is involved, all transformers feeding each building are separately derived and require bonding of neutral to EGC to ground at either the transformer feeding the building, or the service rated transformer in the building with EGC running between the two.

Do you agree?

In addition to to what it Augie said (from memory is it 250.30(A)(1) exception 2 that allows bonding on both ends?) Note that the primaries will probably be set up as an MGN with the primary neutral bonded and grounded at each transformer (250.184 something?)

P.S. there is no such thing as a service rated transformer. You can't have a customer owned transformer without a service disconnect ahead of it.

 

[tom baker]

It might help to define where your service point is? Are you primary metered?