Folks, I have a question that I feel like I'm getting a bit of the run around over. We manufacture UL508a compliant industrial control panels that are then used in our equipment that we also manufacture. I want to add a small stepper motor controller board to the panel that is not recognized or listed. It operates at 24VDC and when our inspector was in last he said to go through UL's site to get a quote on having it added to our procedure. I went and did this and they came back with a quote that ain't gonna fly. I've been lead to believe that a properly fused LV device does not need to go through this process. Our inspector was in again today and I asked him about it and he said it may be LV but if it's not under (3 or 5Amps, he couldn't remember which) then it needs to go through this process to be added. He said as an alternative, I could put it in a seperate box and bolt it to the machine. In another application we use a small LV motion control board (unlisted, and properly fused) that we've had for years and many inspections. Nothing's ever come of it. I heard someone say once that it's because it's on standoffs and not on the panel. I've filtered through the code and I can't derive anything. Can anyone help clear this up or point me in the right direction?

Jim

Jimminie,

Have you looked at applying it under the rules of Appendix B?  See if it can fit in the B1.3 description at all...

Good on ya,

Goober Dave

Does the SELV concept apply to 508 enclosures?  Mostly I deal with 1008 and 1449, both of which defer to 60950, where anything under I think 40V is pretty much free game as long as it meets the double insulation requirement.  I do recall from working with firepump controllers that anything under about 50V the UL engineers didn't even care to see on voltage maps.