First, a little background. I have designed industrial control trinkets for a number of industries over the past 20 years or so. These have all been 10-30 VDC input devices. Some in metal enclosures, some plastic and some potted epoxy. These devices, depending on the industries involved have been UL / CSA / FM approved with no problems. I just ran my first one through ETL, the allegedly cheaper UL knockoff lab. Obscurely hidden in the end of the final report is a requirement to hipot test this device with 840VAC or 1080VDC for 2 seconds. The product is nothing more than an electronic chart recorder with no control capabilites whatsoever. It just monitors thermocouples, control currents and voltages. My big concern is that I have never had any requirements to hipot test any low voltage equipment - EVER. I've done many mains power driven devices and they usually get a hipot test. Common sense engineering would lead me to believe that hipot testing low voltage DC instruments with these levels for 2 seconds would surely damage parts of the instrument, like the 36V TVS diodes across the power inputs. So, did ETL make a mistake in specifying a hipot test? Or am I missing something in the UL-61010 requirements? Thanks, Bill -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist