Outside Branch Circuits and Feeders, Part 5

Suppose you have an outbuilding that doesn’t have its own service. Instead, it’s served by a branch circuit or feeder (on the load side of a service disconnect). This is a common arrangement. For example, an industrial facility may have a guard shack or pump house supplied this way.

One of the rules for this arrangement is only one branch circuit or feeder can supply that building [225.30]. But you can use additional branch circuits or feeders to supply any of the following:

1. Fire pumps.
2. Emergency systems.
3. Legally required standby systems.
4. Optional standby systems.
5. Parallel power production systems.
6. Systems that connect multiple sources.

The AHJ can grant special permission for:

1. Multiple occupant buildings that lack the space for supply equipment accessible to all occupants.
2. Structure large enough to make more than one supply necessary.

And you may use additional branch circuits or feeders if:

1. The capacity requirements exceed 2000A (at 1,000V or less).
2. You need to supply different voltages, frequencies, or phases. Or you need to supply for different uses (e.g., control outside lighting from multiple locations).
3. You have documented safe switching procedures.