I'm looking for some feedback on NEMA versus UL type - environmental ratings for faceplates of panel mounted components. a.. First reality check - Are NEMA housing ratings = UL type, number by number? b.. Second - Can one self certify compliance to NEMA ratings? c.. Third - What is the difference between NEMA and UL type? I think of the NEMA rating as a proof of design test = rating while the UL type wants design verification at a deeper level? d.. Forth - Do any of you care about UL types? Our sister divisions design assemblies that use our components and use UL to inspect the design. That is where the pressure is coming from over NEMA.
Our product line consists of components mounted to the door of an industrial type enclosure. A pollycarbonate faceplate frames an overlay that contains membrane pushbuttons, embedded LEDs and a window to see our alpha numeric or grahpic display. Between the faceplate and the enclosure panel is a gasket to help keep out moisture, dust etc. We can meet NEMA 1, 12, 3, 3R and for some designs 4 as long as the user installs the component in an enclosure of equal protection. We have tested our design at environmental extremes and it works well. Where it gets difficult is when UL wants an adhesive for the overlay that is specifically qualified to our particular plastic over the range of specified environmental withstand. They want more than a type test and follow up construction inspection but a rather lengthy performance test that goes beyond what we are prepared to do - as if we were the overlay manufactures. Part of the problem is that we have a special additive to the PC plastic - stainless steel fibers for ESD control. This is making for special combinations. So what do others do? Do you have overlay vendors that have coordinated recipe of components/adhesive etc. that works with pollycarbonate from -40 to 60C and comply to UL types (NEMA) types 1, 12, 3, 3R, or 4? Thanks for any FB you can give ! Chris Wells Sen. Des Eng. Cutler-Hammer Pittsburgh Pa [email protected]
