MCCB Enclosure Requirements

[cottora]

We currently use matching 400A MCCB and Enclosures (i.e. Square D). To save cost, we are looking at using a manufacturer that does not have a matching UL enclosure. However, the manufacturer does make a UL-listed external handle.

Our plan is to put the UL-listed MCCB in a NEMA 1 UL Enclosure and then mount the UL handle (which keeps all devices listed).

We are hesitant because many of the available enclosures vary greatly in price (which leads me to believe that some enclosures may not be suitable for the above use).

Specifically, the 24x18x8 NEMA 1 box that is pictured would work perfectly for our setup (which is indoors). This enclosure is less than $150, and that seems weird...Are there other considerations we are not thinking about? Thanks in advance!

*the picture is a stock photo and represents the style but not the dimensions.

 

[jim dungar]

That is a cheap junction box type enclosure. It does not have an internal mounting panel for your breaker, which means your mounting screws will stick out the back of the enclosure. It does not have a hinged cover so your external operating mechanism may not mount correctly.

Remember you don't get what you don't pay for.

 

[petersonra]

The assembly won't be UL listed if that matters to you. We routinely put molded case circuit breakers inside standard enclosures, but I don't think I would put it in a screw cover type enclosure. You can get a hinged door type junction box for about the same price.

Possibly the reason you are saying such a discrepancy and prices is because you do not have a purchasing agreement that covers a particular product. Every once in a while I get a price back from a quote that makes me just about fall out of my chair and inevitably it turns out that it's not on our purchasing agreement.

One thing you might want to do is talk to your local supplier and see what they can do for you price wise. Often just asking for a better price can get you a substantially better deal, even these days. It probably won't help you much if you only make a handful of these a year but if you did 20 or 30 a year I'd be willing to bet you could get a pretty good deal from somebody.

 

[cottora]

The assembly won't be UL listed if that matters to you. We routinely put molded case circuit breakers inside standard enclosures, but I don't think I would put it in a screw cover type enclosure. You can get a hinged door type junction box for about the same price.

Possibly the reason you are saying such a discrepancy and prices is because you do not have a purchasing agreement that covers a particular product. Every once in a while I get a price back from a quote that makes me just about fall out of my chair and inevitably it turns out that it's not on our purchasing agreement.

One thing you might want to do is talk to your local supplier and see what they can do for you price wise. Often just asking for a better price can get you a substantially better deal, even these days. It probably won't help you much if you only make a handful of these a year but if you did 20 or 30 a year I'd be willing to bet you could get a pretty good deal from somebody.

I agree that for a little bit more we can get better than what is pictured. That said, you mentioned that the assembly won't be UL listed - why? If the enclosure is listed, the MCCB is listed, and the handle is listed - then from an inspection standpoint, arent all of the components listed?

Put another way, let's assume we used an enclosure that is 5x the price. It has the same UL listing as the low-cost enclosure (at least I think).

 

[jim dungar]

The components must be assembled by a UL 'licensed' company in order to have an overall UL Listing.

 

[ron]

If you put random list parts together doesn't make a listed assembly. Manufacturers go through heat rise testing in a selected enclosure to ensure the parts work together in operating conditions.

 

[petersonra]

I agree that for a little bit more we can get better than what is pictured. That said, you mentioned that the assembly won't be UL listed - why? If the enclosure is listed, the MCCB is listed, and the handle is listed - then from an inspection standpoint, arent all of the components listed?

Put another way, let's assume we used an enclosure that is 5x the price. It has the same UL listing as the low-cost enclosure (at least I think).

Are you sure the handle is actually listed? Usually such things are only recognized. But it doesn't really matter. The assembly is not listed by UL, only the components. Once you put them into an assembly the assembly would need to be listed. I'm not sure what standard you would list it to. I don't believe you could list it to UL 508A because it only has one power component and no control components and I'm pretty sure the standard requires two power or control components.

I suppose you could add a terminal block inside the enclosure and then it would be eligible to be listed to UL 508A.

 

[cottora]

Is it required by code or OSHA to have the assembly listed?

 

[petersonra]

Is it required by code or OSHA to have the assembly listed?

Afaik code does not require it