On Fri, Oct 31, 2008 at 6:44 AM, alan smith wrote: > Low voltage...lower than 48V?? So my device that runs on 24VDC > wouldnt have to be UL certified..based on the fact my external supply > IS certified. Not true. It depends on the device type and your external power supply. It also depends on the customer. Again, I am using UL508 as an example, it examines not only the electrical part, but also the enclosure/construction. If your device is falling under UL508 and is using an external Class 2 power supply (Class 2 is the keyword here), the electrical examination will be quite simple. But still there will be examinations/tests involved if the customer wants UL listed mark. Xiaofan -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist