Control Panel Build

[Rock86]

I had a guy come to me with pump control panel he built and wants to eventually get a NRTL certification.. The build is clean, and very well done but.... serval of the parts of not NRTL listed. Some parts are CE listed, some are UL Recognized (RU), but some have no listings at all. The biggest selling point is a component which is currently Pending a listing. The wire only has a size and temperature rating on the insulation.

Even if this guy decided to avoid the listing, he would not comply with the NEC (110.4(C), 409, 430, etc..). Am I wrong in breaking the bad news to this guy?

 

[DBill64]

UL 508A Appendix B is what you and him need to look at. It covers the use of components not UL listed or recognized in industrial control panels. There are actually a few allowances made for non-listed/recognized parts, BUT there are certain components that have to be listed/recognized (overcurrent devices, GFCI, anything that touches a power circuit, and some others).

The far easier approach though is to simply replace all non-listed/recognized parts with ones that are.

 

[DBill64]

And no you are not wrong to break it to him. If he wants the panel to be listed with an NRTL, then he has to follow their guidelines. Most will be very very hesitant put their sticker on equipment using non-listed/recognized components. If anything you are saving him the wasted time & money of a failed inspection from the NRTL of his choosing. Also I used UL as an example because they are the preeminent NRTL, but CSA will probably have similar requirements for C22.2 recognition of his control panel.

 

[tortuga]

FYI you all are probably aware but UL 508 is not what is was 10 years ago, for over 30 years, significant efforts toward Euro/IEC and North American harmonization have been underway and that train is not stopping. The June 26, 2025, revisions to UL 508A align UL standards even more with the Euro/IEC framework; specifically, UL now recognizes UL 60947-4-1 alongside UL 508 as an acceptable standard for motor controllers. The new version has welcome increased flexibility for electronic devices, disconnecting means, and e-stops. Class 2 circuits can now be powered by sources certified to UL 508, UL 61010-2-201, or UL 61800-5-1.
However, this increased compatibility does not mean one can use random unlisted components and still classify the assembly as a certified control panel. But it might mean more components can get 'recognized', especially if you look into CSA-us or ETL.
It is pretty cool to see how representatives from UL / ETL / CSA now sit on various IEC committees (and vice versa).
You probably notice UL 60947 is replacing many current requirements in UL 508 for several types of industrial control equipment. Additionally, with the rise of VFD's making a regions utility line frequency irrelevant, the 2026 NEC now recognizes 416/240V as a 'standard' voltage (but sadly article 430 lacks a 416V motor table like 508A has Table 50.1)
Ultimately, these changes offer tons of flexibility to design one control panel/process line for both the European and North American markets soon you can design one system for Oregon, Tennessee, Kentucky, and or Estonia, France or Italy .. and so on at a huge cost savings.
But keeping the components sorted is still evolving.

 

[Jraef]

416/240 has been added because it’s a common voltage used in server racks for data centers, not for motors over here. Since the power supplies just convert to DC, they feed them all with 240V single phase, so sourcing it as 416V 3 phase allows them to balance the phase currents in each server racks. By using 240V, they can build the server racks exactly the same no matter where in the world they end up.

A 400V 50Hz motor can already be run with 480V 60Hz without problem (other than the speed difference). So there is no need for a 416V 60Hz motor here.

 

[tortuga]

Good points, that and EV charging that needs lots of 240, say you had one of these data 'campus' parks with primary distribution feeders to buildings, like 4.16kv or 13.5kv like someone recently described, and each building got a 500kVA 416/240 transformer for the data racks.
I'd imagine then it would be logical to have cooling systems that are 416V three phase, and most are probably VFD driven?
You know more about VFD's than me but you probably would not want to use a 416V VFD to bump 416 up to a 460V compressor motor rather have a VFD with a 416V input drive a 400V motor?
Each building would probably have some 120/208 for this and that, but you'd probably not want the cooling system on 208, and you'd not want to install yet another transformer (cost + losses) to get 480, so I could see 416V 50/60 hz cooling being a thing.

 

[Master Nater]

I had a guy come to me with pump control panel he built and wants to eventually get a NRTL certification.. The build is clean, and very well done but.... serval of the parts of not NRTL listed. Some parts are CE listed, some are UL Recognized (RU), but some have no listings at all. The biggest selling point is a component which is currently Pending a listing. The wire only has a size and temperature rating on the insulation.

Even if this guy decided to avoid the listing, he would not comply with the NEC (110.4(C), 409, 430, etc..). Am I wrong in breaking the bad news to this guy?

if all the parts were already UL listed, what would be the point in getting it tested?

 

[DBill64]

if all the parts were already UL listed, what would be the point in getting it tested?

In order to sell it as a complete unit to end-users, you have to get the entire assembly listed by a NTRL. And also, OP stated that not every part was UL listed or even recognized. Some components are only CE.

 

[jim dungar]

if all the parts were already UL listed, what would be the point in getting it tested?

Listing is more than the sum of the parts.
It is the way to know the parts have been applied and installed correctly. Remember an inspector doesn't 'look" inside of Listed items.

 

[Jraef]

Some components are only CE.

CE is not a “listing”, it’s just a self declaration of conformity, it means nothing with regard to getting a panel listed. So those would have to be replaced with listed similar components to be considered as part of an assembly listing.

Also, UR recognized components can only be “added to a procedure” of a UL-508A lusted shop. So I’m not sure they can be used in a field evaluated situation. I’ve never tried though. UR also means they must be used with something else, so hopefully they are also using whatever else that was.

Field evaluations are expensive and you have to pay all of the travel expenses of the inspector. So most of the time it’s less expensive to find a local UL 508A shop and have them modify and list it for him. I used to do that all the time for importers when I had my 508A shop. They can also evaluate it in terms of series listing of components so that he can attain some reasonable level of SCCR labeling rather than the “courtesy” 5kA listing for untested components. A 5kA listing is going to be a burden on you if you are the installer, it’s almost impossible to meet in most industrial situations.

 

[DBill64]

CE is not a “listing”, it’s just a self declaration of conformity, it means nothing with regard to getting a panel listed. So those would have to be replaced with listed similar components to be considered as part of an assembly listing.

Aye, I have had to clarify that with a few too many Engineers. We do not & cannot use components that the only certification of safety is a "trust me bro" from the manufacturer.

Also, UR recognized components can only be “added to a procedure” of a UL-508A lusted shop. So I’m not sure they can be used in a field evaluated situation. I’ve never tried though. UR also means they must be used with something else, so hopefully they are also using whatever else that was.

You are correct that recognized parts cannot be apart of a field listing. They can only be used during the manufacturing of a to-be listed assembly manufactured by a certified panel shop. So unless the guy that OP is referring to owns his own UL 508A Certified Panel Shop, then what he would be doing is getting a field listing. He can ONLY use listed parts for the construction of the panel.

 

[jim dungar]

They can only be used during the manufacturing of a to-be listed assembly manufactured by a certified panel shop.

Sometimes I question UL marketing literature.
A panel shop needs to work with their inspector.

For example, ice cube plug-in relays are UL recognized because they need to be used with a relay base and be mounted into an enclosure. The same is true of industrial pushbuttons and their contact blocks.

 

[Rock86]

FYI you all are probably aware

I hate to say, but I am not. I have not been educated in UL documents and procedures. It is a little embarrassing, but you don't know what you don't know until you learn.