CSA NEMA enclosure getting derated due to external transformer

Merry Christmas
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?
 

SceneryDriver

Senior Member
Location
NJ
Occupation
Electrical and Automation Designer
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?
I went through something similar with UL years ago. I had a NEMA 4X enclosure that had to be listed UL Type 1 because I didn't use the right brand of o-ring sealed screws to mount a device to the inside of the cabinet wall. The screws weren't listed for NEMA 4X. Never mind that the screws were indistinguishable from the ones blessed by UL. Absolutely stupid; the UL overlords are a capricious bunch.

The cabinet ended up being listed on its nameplate as NEMA 4X, UL Type 1. Even our client thought it was ridiculous, and they were the ones pushing for UL listing in the first place.


SceneryDriver
 
I went through something similar with UL years ago. I had a NEMA 4X enclosure that had to be listed UL Type 1 because I didn't use the right brand of o-ring sealed screws to mount a device to the inside of the cabinet wall. The screws weren't listed for NEMA 4X. Never mind that the screws were indistinguishable from the ones blessed by UL. Absolutely stupid; the UL overlords are a capricious bunch.

The cabinet ended up being listed on its nameplate as NEMA 4X, UL Type 1. Even our client thought it was ridiculous, and they were the ones pushing for UL listing in the first place.


SceneryDriver
:mad:
 
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