Enclosure modification and UL type rating

[dang]

Hello all. Our company is embarking on the expensive road that is UL508A listing, and I'm the lucky guy who gets to head up the project. Hooray for me...or not. I did the UL class on 508A, which wasn't terribly helpful as almost everyone in the class wsa already familiar with 508A, so it was more of a fast paced review than a full walkthrough...

So here's the first of many dumb questions I'll have. Let's say I have a Type 4x/12 enclosure. I pop holes in it, put conduit fittings in (listed and not listed), put a homemade fitting in the bottom, a louver plate in the side, and an HMI (no type rating) on the front. The louver plate meets the rules in 508A. All the other holes I've made in the box are completely covered and sealed by the components I've stuffed in there, so there's no ability to get to live parts from the outside.

Do I just put a line through the type sticker on the box, and treat it as a Type 1 enclosure at that point?

Thanks all.
Dan G

 

[weressl]

Hello all. Our company is embarking on the expensive road that is UL508A listing, and I'm the lucky guy who gets to head up the project. Hooray for me...or not. I did the UL class on 508A, which wasn't terribly helpful as almost everyone in the class wsa already familiar with 508A, so it was more of a fast paced review than a full walkthrough...

So here's the first of many dumb questions I'll have. Let's say I have a Type 4x/12 enclosure. I pop holes in it, put conduit fittings in (listed and not listed), put a homemade fitting in the bottom, a louver plate in the side, and an HMI (no type rating) on the front. The louver plate meets the rules in 508A. All the other holes I've made in the box are completely covered and sealed by the components I've stuffed in there, so there's no ability to get to live parts from the outside.

Do I just put a line through the type sticker on the box, and treat it as a Type 1 enclosure at that point?

Thanks all.
Dan G

1. You have no authority to re-rate the box.
2. Why don't you buy NEMA 1 box in the first place.
3. If you wish to maintain the NEMA rating, because the targeted location/application of your equipment, all components that change the external integrity of the box should also comply with the same NEMA rating.
4. If you remove the box's label you may have a general violation of UL508A.

 

[petersonra]

Hello all. Our company is embarking on the expensive road that is UL508A listing, and I'm the lucky guy who gets to head up the project. Hooray for me...or not. I did the UL class on 508A, which wasn't terribly helpful as almost everyone in the class wsa already familiar with 508A, so it was more of a fast paced review than a full walkthrough...

So here's the first of many dumb questions I'll have. Let's say I have a Type 4x/12 enclosure. I pop holes in it, put conduit fittings in (listed and not listed), put a homemade fitting in the bottom, a louver plate in the side, and an HMI (no type rating) on the front. The louver plate meets the rules in 508A. All the other holes I've made in the box are completely covered and sealed by the components I've stuffed in there, so there's no ability to get to live parts from the outside.

Do I just put a line through the type sticker on the box, and treat it as a Type 1 enclosure at that point?

Thanks all.
Dan G

The box itself becomes Type 1.

You generally cannot use unlisted parts unless UL allows you to for specific purposes, which they charge you to investigate for each part you want to use. Things like fasteners are exceptions to this.

 

[dang]

The box itself becomes Type 1.

You generally cannot use unlisted parts unless UL allows you to for specific purposes, which they charge you to investigate for each part you want to use. Things like fasteners are exceptions to this.

Okay, thanks. I think I got a little confused with the rules for openings for ventilation there. I just remember from the 508A class someone mentioning drawing a line through the sticker with the type rating, to signify that it's been reduced to a type 1. For some reason I had it stuck in my head that you could use an unlisted component (conduit fitting, HMI, whatever) to fill in the hole and keep a type 1 rating as long as you couldn't access live/arcing parts - sounds like that's wrong.

Eventually I'll have a little of this stuff figured out...

Dan G

 

[petersonra]

Okay, thanks. I think I got a little confused with the rules for openings for ventilation there. I just remember from the 508A class someone mentioning drawing a line through the sticker with the type rating, to signify that it's been reduced to a type 1. For some reason I had it stuck in my head that you could use an unlisted component (conduit fitting, HMI, whatever) to fill in the hole and keep a type 1 rating as long as you couldn't access live/arcing parts - sounds like that's wrong.

Eventually I'll have a little of this stuff figured out...

Dan G

Its usually not necessary these days but you can use some unlisted parts if you put them on a GFCI. There are limits to how large of a hole you can cut in a panel that can be filled with an unlisted part though.

 

[Jraef]

NEMA 4 and Ventilation.
Think about that for a minute... Why pay more for the NEMA 4 box?

 

[petersonra]

NEMA 4 and Ventilation.
Think about that for a minute... Why pay more for the NEMA 4 box?

He actually said 4X in his OP.

I could buy into 4/12. 4/12 enclosures are about the same price as 3R enclosures most of the time if you are on the right discount list.

 

[renosteinke]

This thread has been bothering me from the start, but I have found it difficult to put words to my concerns. Let me try today:

The box is listed as it comes out of the factory- period. Ditto for the fittings. Yes, UL tests will take into account the intended uses for the product- but there are limits.

A listed box, with a listed fitting, correctly used, will NOT be a listed assembly. Never. Yes, there is a presumption that the proper assembly will maintain the ratings ... but it's still not a listed assembly.

It's not really up to UL. That's not their job. Rather it is the installers job to 'do it right,' and the job of the AHJ to make the evaluation. I find folks tend to try to hide behind UL far too much. It's best to think of UL as little more than an "Inspected by #14" tag on the box.

 

[petersonra]

This thread has been bothering me from the start, but I have found it difficult to put words to my concerns. Let me try today:

The box is listed as it comes out of the factory- period. Ditto for the fittings. Yes, UL tests will take into account the intended uses for the product- but there are limits.

A listed box, with a listed fitting, correctly used, will NOT be a listed assembly. Never. Yes, there is a presumption that the proper assembly will maintain the ratings ... but it's still not a listed assembly.

It's not really up to UL. That's not their job. Rather it is the installers job to 'do it right,' and the job of the AHJ to make the evaluation. I find folks tend to try to hide behind UL far too much. It's best to think of UL as little more than an "Inspected by #14" tag on the box.

Except in this case it is a listed assembly. The OP was talking about a UL508a listing. UL508a requires the manufacturer to mark off the type listing if the enclosure is modified in some way so that it no longer meets the type requirements, but still meets type 1 requirements. There are some exceptions to this rule. For instance, you can put holes in a type whatever cabinet and still list it as long as you put a sticker on saying that whatever goes in the hole has to meet the enclosure type requirements. This would allow a manufacturer to install holes for conduit fittings without actually supplying the fittings.