UL508A Fastener Question

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rodneyl

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We build Industrial Automation Equipment, and have had several NRTL inspections over the years to have our custom control panels inspected to UL508A. We had our first experience yesterday where our panel was failed by a UL inspector because we drilled and tapped or drilled through the enclosure to mount the nameplate and other Electrical items such as internal Lighting and a Ground Bar. His reasoning is because the hardware we were using is not a listed component that is certified to meet TYPE 12 by UL. Therefore, the Enclosure rating needs to be derated to TYPE 1. Has anyone else run into this? Has anyone ever found listed hardware, nuts, bolts, etc. I get the concept of sealing washers for conduit entries and such but an M3 bolt that affixes a nameplate to a control panel door?
 

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It been a number of years since I’ve been involved in control panel design, but I think the inspector is technically correct. We always used adhesive-mounted nameplates.

If you require the N12 rating, you may need to run the appropriate test post-assembly to prove its compliance.
 
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Interior components such as the ground bar pictured can be mounted to the back panel or stud welded. We use a little capacitor driven stud welder that is quick and easy to use.
 
Thanks for the feedback this has been a bugger, we actually have a stud welder, never thought of that, maybe that will at least solve the ground bar issue. I found a company today that actually has type 12 listed nuts, bolts, sealing washers that I am engaging as well. I will keep investigating this topic as it has captured my attention.
 
I did find in UL508A that a section states.
52.4 Markings required to be placed on an industrial control panel as specified in notes (a) - (d) and note (f) of Table 52.1 shall be made by die-stamping, silkscreening, or etching in metal or plastic or with an indelible ink on adhesive-backed label stock and permanently attached to the industrial control panel by rivets, screws, or adhesive.
Has anyone ever seen a UL listed rivet?
 
It's a technicality that 99% of UL inspectors I have encountered over the years basically ignore, so long as there IS a screw or bolt in the hole. Where I've been nailed is when a shop guy drilled an errant hole and did not put a screw in it. But yes, I have run into a couple who have made a stink about it. On one of them, I used some Hoffman NEMA 12 JIC boxes that CAME WITH holes in the back and they gave us sealing washers to use on the mounting bolts. We had to dig out the mounting instructions showing they were PART of the enclosure design, ergo part of the UL listing. Problem was, this was in the days before the internet, so because Hoffman was in Minnesota and we were in California, we had to wait until the next day to get the instructions faxed to us. After that, we took to keeping all the instruction sheets that we used to immediately toss, but of course, that never happened again.
 
The fasteners themselves are not required to be listed.

However, if you make a hole in the enclosure it reverts to type 1 unless you close the opening with an appropriate device of some sort such as a UL listed sealing washer.

There are also UL listed sealing screws.
 
According to UL representative I met with this morning, both sides of the hole in the enclosure must be sealed. Meaning that in order to properly mount the nameplate we would need sealing washers behind the nameplate and a sealed nut on the inside of the enclosure. Seems a little overkill but I guess they wrote the book. So I guess that's where we are headed...!
 
rodneyl said:
According to UL representative I met with this morning, both sides of the hole in the enclosure must be sealed. Meaning that in order to properly mount the nameplate we would need sealing washers behind the nameplate and a sealed nut on the inside of the enclosure. Seems a little overkill but I guess they wrote the book. So I guess that's where we are headed...!
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I’d challenge that. If the mnf instructions state type 4x (or whatever) rating is maintained when installed in such and such fashion, then there’s the rule.
In the case of apm hexseals, one sealing washer in the inside does it.
I’m interested to hear what their reasoning is - I’d be requesting supporting documentation.


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