UL certification for electrical enclosure??

[PEQ]

At my company we design PLC/HMI systems and we put everything in a steel enclosure.

We only uses UL certified components but recently we have customers in a few states DEMAND that the finished and wired enclosure be UL certified.

How is this done?

Can I certify this or does UL need to do this? I cannot see it being feasible for UL to come and do this due to additional cost for each enclosure.

Thanks.

PEQ

 

[btrueblood]

1. You can apply to UL to come and certify your specific box. ETL can do this too, sometimes cheaper. This is expensive, and will be a recurring cost for every panel design/build and every change to every panel and every recurrence of production of those specific panels...you get the idea. If you do one panel design in serial production, and the design hardly ever changes, then it may be worthwhile (we do this for one type of panel).
2. Find a UL certified control panel manufacturer - these guys have UL certification to build control boxes using UL recognized materials and components and do the work per UL standards, to function per the user's specifications. They do the work of #1, for a fee, but usually cheaper for the one-off stuff than #1. The underlined term is your google search entry, also try UL 508A and UL 698A and NFPA 496 as well, depending on the type of panel you are building, or having built.
3. Find a UL label and copy it, attach it to your product. This is the cheapest possible method, but comes with a hidden follow-on cost: you take the money and get out of town, because once somebody checks the listing number, and finds that manufacturer never built your panel or ever heard of you, then you are in trouble.
Edit: added #3.

 

[jraef]

Just to be clear, #3 is criminal fraud, and I’m sure btrueblood was making a tongue-in-cheek suggestion...

But semantically, you say “enclosure” which to me means the box itself. Are you asking if you need to have the entire control panel ASSEMBLY UL listed, or are you being specific to the BOX itself, i.e. you are using a custom shape or arrangement for the sheet metal and making it yourself rather than buying a manufactured electrical enclosure?


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[controlsdude]

I would recommend a UL panel shop to build your panels.

You can build your own panels and get it UL qualified. Contact a UL rep in your area. Go over what you need for a person onsite to be your UL qualified engineer. Then UL rep will visit 2x a year to make sure your following the standard.

UL panel is basically the items below:
All components inside panel and including panel is UL.
FLA calculation follows a certain standard.
All components that need air flow have certain air flow deminsions.
All vents cant have an arcing components minimum certain distance from vents.
Panel when shipped has to have all the components on drawings inside panel or panel shop cant put their label on it.
Set of drawings inside panel.

 

[LionelHutz]

I would evaluate the need for your shop to get it's own UL508A panel shop listing. Someone has to take a 2 or 3 day course and the shop has to follow the requirements of the standard which lets you self label the panels. An inspector will then show up about every 3 months to ensure you're doing it correctly.

https://industries.ul.com/blog/become-a-ul-listed-panel-shop