What about a device with, say, a soid state relay that switched AC? -marc On 2/14/08, Matt Pobursky wrote: > On Thu, 14 Feb 2008 12:54:35 -0800 (PST), Harold Hallikainen wrote: > > It SEEMS that we end up spending thousands of dollars to get UL safety > > testing on the following: > > > > 1. A UL listed power supply > > 2. A UL listed power switch > > 3. A UL listed power inlet > > 4. A few pieces of wire and a ground lug > > > > > > It SEEMS that it should be possible to avoid all this if there were > > something like the old PC power supplies that had the inlet, power > > switch, etc. all enclosed in a box with just the DC outputs coming out of > > the box. We'd shove the power supply up against our rear panel and have > > no line connected circuitry in our product other than that "pre-approved" > > box. > > > > I think this is similar to using an external low voltage power > > supply. > > No, there is actually quite a large difference in U.L.'s eyes -- using a > wall wart no high voltage is contained inside your enclosure, only isolated > low voltage via your power cable. In the case of an enclosed AC mains > operated supply inside your box you are also introducing mains voltage > inside your box. Yeah, it's in a can but it's still there and stuff > happens. That's how U.L. will look at it, even if it's a U.L. listed power > supply module. > > > So.. does the group think this would reduce or eliminate UL safety > > testing costs? Does anyone know of any power supplies like this? > > It depends on the specification you're trying to meet and what the target > industry expects. In the industries I design for (medical devices, fire > alarm and detection systems and industrial controls) I would expect to > actually have more U.L. safety tests because AC mains voltage is now inside > the box. > > Matt Pobursky > Maximum Performance Systems > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- Sent from Gmail for mobile | mobile.google.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist