Service and generator grounding/bonding - ATS poles

[joe_vince]

Here's the situation:

2 school buildings located next to each other. Both only 3 stories tall. Both have incoming service rated 120/208V, 3-phase and each building has its own service that enters main switchboard. Neutral is grounded at each switchboard.

Generator on Building 1 serves both the buildings. Engineer provided non-separately derived generator at Building 1 with 3-pole ATS's. Generator feeds Building 2. Should the ATS's in Building 2 be 3-pole or 4-pole? Reviewer is adamant that 3 pole is required at both buildings per NEC 250.30. Thoughts?

 

[augie47]

The two ATS should match. The ATS would make the determination=on if the generator should be treated as a SDS or not.
Most common ona 3 phase system would be a 3 pole/S/N and the generator not a SDS>

 

[hhsting]

Here's the situation:

2 school buildings located next to each other. Both only 3 stories tall. Both have incoming service rated 120/208V, 3-phase and each building has its own service that enters main switchboard. Neutral is grounded at each switchboard.

Generator on Building 1 serves both the buildings. Engineer provided non-separately derived generator at Building 1 with 3-pole ATS's. Generator feeds Building 2. Should the ATS's in Building 2 be 3-pole or 4-pole? Reviewer is adamant that 3 pole is required at both buildings per NEC 250.30. Thoughts?

Both buildings ATS poles should match however it is up to the engineer not the reviewer to determine if both buildings ATS is 3 poles or both building ATS is 4 poles. Should the engineer make both building ATS 4 poles then generator is SDS. However if the engineer decides to make both buildings ATS 3 poles then generator is non SDS.