Panelboard Mounted in Enclosure - UL 508A Listing Required?

D

douglas.nixon

Member
Location
Minnetonka, MN
Occupation
EI&C Enginner
Hello everyone! Longtime information consumer, first time poster.

I have a city inspector that is rejecting an enclosure of mine that contains a 120/240VAC dead front panelboard (no sides) mounted on the back panel inside a Type 4X Hoffman box. I've no idea of this inspectors background but when asked why it cannot be used he states that it is missing a UL sticker which I take to mean that he is expecting it to be UL 508A Listed.

https://i.ibb.co/QjmdJGVW/Resized-20250218-105814.jpg

What information could I provide to show that this should not be a listed enclosure and it is acceptable as is?

Thanks,
Doug
 
tom baker said:
It’s the other way around. The AHJ should give you the code section
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Hi Tom. Sure, I understand that, I'm trying to educate myself as much as possible on the subject so that I can either accept and understand what he says as true or gently lead him to the path of understanding myself.
 
I believe his objection might be that the enclosure itself may be unlisted. Did you by some chance have one made instead of buying one off the shelf?

Or maybe you covered up or cut out the place where the ul sticker was.

Hoffman boxes usually have stickers like these on the back of doors or sometimes inside the enclsoure.

1742405364234.png
 
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If the UL listing of the panelboard says that it includes its own box, and you have eliminated the box, then you have voided the UL listing of the entire unit.

I believe that UL -508a includes using UL-67 listed panelboards in their procedure, at least they used to when I was a UL shop, and I used to use Square D NQOD panels, because the interiors were listed without the box. Maybe someone else with more current info on UL-508a can check in on that.
 
petersonra said:
I believe his objection might be that the enclosure itself may be unlisted. Did you by some chance have one made instead of buying one off the shelf?
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The enclosure that a panelboard is installed in is a cabinet, covered by Article 312. That article does not require the cabinet to be listed.
 
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