In the US, if it does not have a UL certification, legally we cannot install it. Most electrical inspectors will look for that UL certification. If that certification is not affixed to the equipment, he/she probably will not sign it off until a certification is presented.

Before you build something, I would recommend you find out what the rules are in your area.

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We had a Cutler-Hammer ice cube relay for slide projector switching installed by an electrician recently, and the electrical inspector refused to sign it off until the contractor provided a UL certification for that relay.

What a butthole!!!!!!

At the radio station, our 5KW transmitter had a 3-phase surge suppressor that was supplied with the transmitter package. When we lost the radio station to a flood, we moved the transmitter to higher ground, and got back on the air. When we had a new transmitter facility permanently in place, we installed the surge protector. The electrical inspector would not sign it off until I produced a UL Certification.

Same Crap - Different shovel - Different day - Different month - Different year - Different butthole!

So it is not just the inspector - apparently, it is the law.

do you need serial control, or simple relay closures to control everything you want to control?

Any old PC could easily do any automation.

If you are talking about pulse logic such as what DTS, Dolby, or others use, whether it be dimmers or what have you where there is no appreciable voltage present or no apprecialble current draw on contact closures, the switch cards available for the average run-of-the-mill computers will probably work just fine.

We use those cards for audio source switching via soft pulse logic in the broadcasting industry.

I use the term "soft pulse logic" (although it may be politically incorrect) to describe extremely low current and low voltage switching via some goofy IC flat pack.

Why fart with it? It still might not pass certification, unless it was a total "plug-in" package that had the whole shebang approved. I am sure you can build something that will work along with many of us. But, if it is not certified, forget it. It will probably be rejected, even though your device may be better and more reliable than some of the crap that is manufactured today.

Sometimes I think it boils down to "who is in bed with whom" when the certifications are issued.

The final point is....The damned thing still has to be certified if it is going to be used in an industrial application. Without the certification, you might be held liable in event of a fire or some catastrophe that results in a loss of life or injury.

UL standards are based in good measure on the National Electrical Code (NEC) which IS the law in most locations (although I am not certain if all jurisdictions consider it the law). UL tests electrical and electronic equipment to see if it meets certain minimum safety requirements regarding fire and shock hazards. By the way, there are other testing labs besides UL which are legally acceptable anywhere in the country. I have used UL and one other lab, ETL, for my testing needs. These are known as NRTL's (Nationally Recognized Testing Laboratory).

Many localities insist on UL or some other lab certification because they know these products have met NEC conditions as part of their testing.

The real problem to me is that so many electrical inspectors THINK they know what the NEC says. If you have ever looked at the NEC, it can be most confusing. I am a reasonably intelligent person, and I am confused by much of what I read in the NEC. So much of it seems so open to interpretation.

Steve

One thing I question about NEC is when the NEC is incorporated by reference as part of a given city or state's building code whether they can legally incorporate the ongoing, periodically updated NEC. In other words, I can see a governmental body adopting say, the 2000 NEC, and then when 2002 comes out adopting the new version as a separate legal act. But to simply adopt NEC as the law of the land on a blanket basis when this is a document which is then altered by a private organization would seem to me to be an illegal delegation of law making authority to a private party. I don't know if this is done or whether, as I have said, they adopt a particular version and then adopt the next one when it comes out. If the former then someone should challenge it because it certainly doesn't pass the smell test.

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