Auto transformer

[NAMAHDDUB]

Do I need primary protection on a auto transformer that is 208v three phase input and 230v three phase output 15.9KVA? I always thought all transformers needed primary protection with the exception of a couple cases. I have another electrician that is trying to tell me other wise, but I think he is just trying to get out of having to reduce the size of the fuses on the feeder.

 

[Jberg73]

I've always used protection on the primary side. I've never seen or read anything to suggest otherwise.

Jason

 

[NAMAHDDUB]

The code requires it for transformers period and I do not see any exceptions for auto transformers, just wondering if I am missing something.

 

[david luchini]

The code requires it for transformers period and I do not see any exceptions for auto transformers, just wondering if I am missing something.

You need input protection per 450.4, not primary protection per 450.3.

 

[NAMAHDDUB]

The other guy admitted that he was incorrect and needed to protect the auto transformer. Thanks for the input