ECN Forum Forums Code Related Discussion NEC & other Code issues Using not Listed Equipment at 24VDC

Hello,

We (a german company)want to build up an inspection machine, based on 24VDC.
As a power supply we use a listed power supply 3x400VAC In -> 24VDC Out.
At the 24VDC output there are connected a UPS and a 24VDC power-supply for a PC.

Whats about the components on the secondary 24VDC side. Must they be UL-listet?

I have heard that component on secondary circuits must not be listed.
Are there exceptions?

I think the simplest way of getting answers to your questions is to contact UL.

Some of the questions likely to arise can be answered by the tech info pages at B-I-A (Some in English, some only in German)
http://www.biagmbh.com/techinfo.htm

I would however like to point out that 3x400V input is a poor choice for use in North America. No such voltage is in use which would force the user to install a transformer for your equipment. For dual use Europe/North America I would suggest you consider using 220-240V single phase instead, as it is a voltage available in almost all countries of the world. (200-240V nominal covers the entire world.) If the power demand is too high to be suitable for this, I'm sure the Americans reading this can tell what is normally available in these locations. (Hospitals?)