drktmplr12
Senior Member
- Location
- South Florida
- Occupation
- Electrical Engineer
Edition: 2014 NEC
I am having trouble coming to terms with the application of 225.32, Exception 1 and 225.36 requirement that equipment be service entrance rated. I have a unique application:
The plant has two buildings, each with a 480V service from two different transformers. Each 480V service has a main circuit breaker. Each building also has a generator with a main output breaker, connected to an ATS. The ATS is connect The Owner would like to interconnect the two buildings and power the process from either service or generator.
I do not believe I need a neutral between the two buildings, but need to confirm this. Assume all distribution is 3P4W. I've notated what is desired on the one-line in red.
It's clear what to do when the feed only goes one direction and there is a neutral carried between the two buildings. My confusion is (1) there is no neutral to be carried between and (2) that the feed is intended to go either direction and both sides would require SE disconnect per 225.36. How exactly should the grounds be connected between the two (apparently) required SE disconnects for each branch circuit?
Currently the thought is to have an equipment ground connect the ground bus in the MCC and SWBD. Am I missing something?
The one-line shows a switchboard with a new breaker, but I'm thinking that may have to be a SE breaker in a separate enclosure.
Elementary One-Line
225.36 Refers to 250.32(B)
I am having trouble coming to terms with the application of 225.32, Exception 1 and 225.36 requirement that equipment be service entrance rated. I have a unique application:
The plant has two buildings, each with a 480V service from two different transformers. Each 480V service has a main circuit breaker. Each building also has a generator with a main output breaker, connected to an ATS. The ATS is connect The Owner would like to interconnect the two buildings and power the process from either service or generator.
I do not believe I need a neutral between the two buildings, but need to confirm this. Assume all distribution is 3P4W. I've notated what is desired on the one-line in red.
It's clear what to do when the feed only goes one direction and there is a neutral carried between the two buildings. My confusion is (1) there is no neutral to be carried between and (2) that the feed is intended to go either direction and both sides would require SE disconnect per 225.36. How exactly should the grounds be connected between the two (apparently) required SE disconnects for each branch circuit?
Currently the thought is to have an equipment ground connect the ground bus in the MCC and SWBD. Am I missing something?
The one-line shows a switchboard with a new breaker, but I'm thinking that may have to be a SE breaker in a separate enclosure.
Elementary One-Line
225.36 Refers to 250.32(B)