SSBJ vs EGC

[Dsg319]

Confused on how to size SSBJ vs EGC. Say I have a smaller 75KVA transformer 480/208v delta-wye. No parallel conductors. Which table do I use for SSBJ from transformer to first OCPD. Do I use 250.102(C)(1) or 250.122

 

[infinity]

250.102(C)(1) because 250.122 is based on the OCPD size ahead of the conductors. For the transformer secondary conductors there is no OCPD before the disconnect.

 

[Dsg319]

250.102(C)(1) because 250.122 is based on the OCPD size ahead of the condcutors. For the transformer secondary conductors there is no OCPD before the disconnect.

Thank you for your explanation! Clears things up. I guess word parallel in there had me confused. Thought maybe that was the only time you used it.

 

[Dsg319]

I would assume from an inspectors standpoint and experience that would be a fairly common violation is undersized SSBJ, due to the fact people just using the same size and the EGC.

 

[ron]

I would assume from an inspectors standpoint and experience that would be a fairly common violation is undersized SSBJ, due to the fact people just using the same size and the EGC.

Agreed, I've been guilty of it myself because it is easy to think the conduit in / out of that first disconnect would be exactly the same, but as you pointed out, the SSBJ is generally different than the EGC which would be sized on the OCPD in the disconnect.

 

[Dsg319]

Yup.

Agreed, I've been guilty of it myself because it is easy to think the conduit in / out of that first disconnect would be exactly the same, but as you pointed out, the SSBJ is generally different than the EGC which would be sized on the OCPD in the disconnect.

Yup I’m sure I’ve par-taken In it too. I done some comparisons last night and anything really over 100amp the EGC is smaller than the SSBJ.