OT: UL Approval of Non-Listed Devices

This is WAAAY off-topic but someone has probably run into this.

We are building a machine for installation into the St Paul, MN area. It will require UL inspection before being put into service. In one of the control panels we have controls for a heat seal system that are not UL approved or recognized. The system is manufactured in Germany and is CE marked but no UL. We used one of these systems last year and had a design that allowed us to use these components. However, UL enforcement rules apparently changed since last year and the design we had doesn't pass. In fact it appears that there are no design methods available to allow use of a non-UL device in what is considered a 120VAC power circuit. We are told the only thing available to us is an on-site UL Field Evaluation.

Does anyone out there have any experience with applying non-UL devices in a UL approved assembly?

Thanks,
Keith

for a ul "field" evaluation.
rules may have changed since 2004, so here goes.

the rules i know are for becomming a ul listed panel shop.

build panels to ul508a standards! keep documentation for everything ! lots of paperwork and designs to submit.

you will have to submit multiple panels - build 2 of everything. for 3 panels or more.

one will be for destructive testing at the ul test site.
the other will go o the customer.

this is a very nit picky process - i'm not joking. these guys will tag you for the smallest of defects.

regards,
james

UL interprtation is very dependent on the individual inspector.

One thing that usually helps is to put a GFCI in the circuit protecting all components that are not 508 listed and in your folder. (One inspector said that they don't care if the other end of the wires are in a bucket of gasoline once the GFCI is there.)

Just a quick update.

It turns out that someone had tweaked the electrical design since the last machine. It looked enough the same that I didn't look at it as closely as I should have. On the previous panel the GFCI protected the non-UL controller. On the current design the GFCI protected the power components. Once we got this straight things became alot easier to deal with. We still needed to find a UL listed isolation transformer for upstream of the GFCI and a UL listed general purpose transformer for the power circuit. But at least now we have a viable path for UL approval without a field test.

Thanks for the comments.
Keitih

Geez - glad the silly buggers are not in Ozz!

BobB said:

Geez - glad the silly buggers are not in Ozz!

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You have no idea, Bob. UL inspectors combine the most obnoxious aspects of greedy capitalism, arrogant condescending charity organizations, and indifferent government bureaucracy.

Tom Jenkins said:

You have no idea, Bob. UL inspectors combine the most obnoxious aspects of greedy capitalism, arrogant condescending charity organizations, and indifferent government bureaucracy.

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I have to say that I have had a different experience than Tom and some other people I know. I have a good relationship with our inspector and don't feel like we have been subject to nit picking or efforts to ding us at all costs.

I think the intended purpose and spirit of UL508 is quite good: To prevent shock and fire. If an inspector keeps this goal in mind then there are usually no problems. From observation it seems some new inspectors or inspectors with their bosses in tow think if they don't find a problem during the inspection that they will get in trouble. Call me stupid but if they demonstrate to their boss that a client is doing everything right, this should be the goal. If the inspector has to ding every client, and I was their boss, I'd wonder what they had been doing when I wasn't there?

One other thing I have heard (no solid proof) is that the inspectors are assigned by region not specialty. That could mean that your panel inspector may not be an expert in industrial control panels but hair dryers or water valves.

The latest word on the street at least in Northern Illinois is that people are getting dinged for not having their torque screwdrivers calibrated.

Anyway, it seems like I'm in the minority but I have had a generally good experience with our inspector.