Sealing Washers to Keep NEMA 12 Rating

[richwaskowitz]

Although I have been told by our UL rep that there are products out there which will allow one to penetrate a type 12 enclosure and attach a component such as an enclosed transformer or DB resistor to the outside of the enclosure using machine screws and through holes, I cannot find any product specifically for that purpose. Those products are required to be "components intended for such mounting... that have been evaluated for the enclosure type" (UL 508A 19.3). They (UL) told us in no uncertain terms that simply sealing the penetration with sealant or a neoprene washer for example does not meet the requirement. Just because the hole is threaded or seems to be oil tight does not cut it.

Can anyone point me to such a product (washer, sealing ring , etc.)?

 

[SceneryDriver]

Although I have been told by our UL rep that there are products out there which will allow one to penetrate a type 12 enclosure and attach a component such as an enclosed transformer or DB resistor to the outside of the enclosure using machine screws and through holes, I cannot find any product specifically for that purpose. Those products are required to be "components intended for such mounting... that have been evaluated for the enclosure type" (UL 508A 19.3). They (UL) told us in no uncertain terms that simply sealing the penetration with sealant or a neoprene washer for example does not meet the requirement. Just because the hole is threaded or seems to be oil tight does not cut it.

Can anyone point me to such a product (washer, sealing ring , etc.)?

My UL rep pointed me toward these:

http://apmhexseal.com/self-sealing-fasteners/screw/

They're apparently the only listed screws for use when needing to maintain a NEMA4 / 12 rating.

Or, you could do what I did on a recent project, and simply label the panel "UL Type 1 / NEMA 4" In my case, it's because NO ONE makes a UL Type 4 -listed Ethernet bulkhead passthrough, though everyone and their uncle makes an IP-66 rated fitting. My client was OK with the panel listed that way, and had dealt with the issue the same way before.

UL is still thinking about how to "accommodate" IP-rated devices in 508A panels - they've been thinking about it for years, and I'm told a decision will be forthcoming shortly.

It's one of the maddening things about UL; common sense often takes a back seat to paperwork being blessed by the overlords.


SceneryDriver

 

[richwaskowitz]

Thanks Scenery Driver. I will try those. Yes, we know we can label as type 1 but the customer specs type 12 and we want to keep it that way. These openings are the only drawback.

 

[Jraef]

Note that those are UL Recognized, not listed, which is to be expected. Recognized means they don't do anything by themselves, they need to be used as part of a system with other components, in this case the enclosure. All that means though is that if you are a UL panel shop, you must "add them to your procedure", which involves paperwork describing exactly how you will use them and a small fee to UL.

That said, your UL guy is being a Richard head... Mine used to allow any kind of machine screw with a sealing washer.
https://www.nutty.com/Bonded-Sealing-Washers_c_115.html

Hoffman (Enclosure mfr) used to sell them in their catalog, I don't see them now, but maybe because you can get them pretty much anywhere.