Size of System Bonding Jumper for a 2KVA transformer with a 120V secondary.

[LPS]

Probably a silly question, but Table 250.102(C)(1) says 8AWG copper for anything 2AWG copper or smaller. I'd expect to see some kind of exception for smaller transformers, but I can't seem to find it. Thanks

 

[don_resqcapt19]

There is a very specific exception in 250.30(A)(1) but it is very limited in application and only applies to 1kVA and less. See Exception #3.

 

[infinity]

I'd expect to see some kind of exception for smaller transformers, but I can't seem to find it

Are you thinking that small transformers should not have a grounded neutral? I can see no GEC but with a 120 volt secondary the neutral would still need to be grounded via an SBJ.

 

[LPS]

don_resqcapt19​

Yeah, I looked at that, but when I saw that the mention of class I, class II, and class III circuits I dismissed it. But now that you mention it, the applications I would use this for is a class I circuit. My brain jumped to class III circuits for some reason... Thanks for pointing my back to where I needed to be.

 

[LPS]

Are you thinking that small transformers should not have a grounded neutral? I can see no GEC but with a 120 volt secondary the neutral would still need to be grounded via an SBJ.

No. I always ground the "grounded" conductor... lol. I was just a little puzzled that Table 250.102(C)(1) only went down to 8AWG and didn't say something like "but does not need to exceed the size of the largest conductor". Mr. don_resqcapt19 referred me back to 250.30(A)(1) again, and now that I think about it, the application I generally use a 2KVAish transformer for is a class I circuit, although I could imagine a situation where it wouldn't be a class I circuit, and I guess in that case the code is requiring an 8AWG SBJ on a transformer supplying a 15A circuit. I'm probably missing something... All good.