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Discussion Starter · #1 ·
I have a project that the customer is requiring us to have the enclosure meet NEMA 12 standards. The control transformer we selected is rated NEMA 3R. It is mounted to the side of the enclosure. Our panel shop is saying that due to C22.2 486-17 4.7.1, the transformer forces the panel to be derated to NEMA 1. The way I see it, only the penetrations for the transformer need to meet NEMA 12.

Is this true? Would this change if the transformer were mounted independent of the enclosure and the only connection between the 2 was conduit?
 

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Discussion Starter · #6 ·
Our customer is requiring our delivered panels to have a NEMA 12 rating. We don't get it, but it is in their spec.

To be a certified panel shop, they have to call us out on things like this, or else they can lose their certification. We have already purchased transformers or else we would substitute NEMA 12 and not worry about it. NEMA 12 transformers have a 6-8 week lead time, so we need to figure something out with what we have on hand.
 
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