Allowed Modifications to UL508 Panel 1

[hwmcginnis]

We have delivered industrial control panels manufactured by and in accordance with UL508.

Since connecting field wiring does not appear to invalidate the UL508, what other modifications can be made?

For example, if our current digital outputs are merely contacts to field devices and now we find we need to source voltage for a solenoid, does the wiring of this circuit violate UL-508? The sourcing power supply is present in the ICP, spare breakers are present and other than wires, no components are added or removed.

 

[jraef]

UL508 is a standard for assembly, engineering and testing. It has almost nothing to do with functionality (as long as you are not using something for other than its intended purpose). So if all of the components were present in the panel when you labeled it, and you are using and wiring them in the same way, I see nothing wrong with it.

That said, UL does not allow "field modifications" without re-inspection. In other words, it is not specifically the PANEL that is UL-508A listd, it is the shop that assembled it. So if further work iks done outsie of that shop, that work would be in technical violation of the UL labeling of that panel.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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[DRWeig]

jraef hit the nail on the head very well.

I have a panel shop, we've gone through this stuff many times.

Part of the listing involves making sure that all loads are accounted for -- if you're adding a load in the field to a power supply that's part of the panel, you would need to make sure everything is still in compliance afterward, adjust the load numbers on the label, and have it re-investigated on site to maintain the listing. That is, unless the spare circuit breaker you're referring to was assigned a load at time of production and has been already accounted for.

In my area, our inspector would require us to go do the field mod to the panel, in his presence, and re-calculate the new load on the power supply -- checking it against the allowable load in the standard.

Let us know how it works out for you!

Good on ya,

Goober Dave

 

[jraef]

... and don't forget to mention the invoice the UL inspector will send for his field visit....


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[jraef]

Hit the submit button too fast.

When I ran a UL508 shop, we generally found that it was less expensive to return the panel to the shop, re-label and document it, then send it back. The field inspection fees can be exorbitant.


_{Sometimes all we did was pick it up, hold on to it for a day or so at a local motel and take it back with a different label, then document the changes internally for when UL showed up for their surprise inspections.}


Wait, did I say that out loud?


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[DRWeig]

jraef,

I'm sure that never (ahem) really happened. I must have mis-heard you since you were talking so softly.

Glad you mentioned fees. (the simplest of all field trips today start at about $1500 for re-investigation PLUS EXPENSES). I forgot, too, about labels. The new stuff would have to be all nicely labeled up and the drawing would have to be re-done to match what's there too...

It's a racket!

Goober Dave