UL508 listed UPS

[ramjr]

We recently completed an Industrial Control Panel for a Waste Water Treatment Plant. Our UL inspector would not allow us to use a UL 1778 listed power supply. He said it had to have a UL 508 listing. I've called Tripplite, APC, Eaton and they all say they use UL 1778 not UL 508. We got our UL listing by removing the UPS and plugging the pigtail into the receptacle and stating the UPS is a optional accessory. Their should be a better solution. I know we are not the only UL panel shop that uses UPS's as backup for PLC's and instrumentation. Help! How can I conform to UL and include the UPS (3KVA)? :?

 

[Jraef]

We recently completed an Industrial Control Panel for a Waste Water Treatment Plant. Our UL inspector would not allow us to use a UL 1778 listed power supply. He said it had to have a UL 508 listing. I've called Tripplite, APC, Eaton and they all say they use UL 1778 not UL 508. We got our UL listing by removing the UPS and plugging the pigtail into the receptacle and stating the UPS is a optional accessory. Their should be a better solution. I know we are not the only UL panel shop that uses UPS's as backup for PLC's and instrumentation. Help! How can I conform to UL and include the UPS (3KVA)? :?

He is technically correct, but he is being a Richard head. Technically, you cannot put anything into a UL508A listed CONTROL panel that is not listed in the UL508 book, which describes all of the other UL standards that are acceptable within 508A. But unfortunately, UL1778 is not on the list, at least not as of 2005, the date of the book I have here. I have a newer version at my other office, I'll check it for you or if you are a 508A panel shop, you should have it too. The list of acceptable standards for products is table SA1.1 in the back of the blue book.

However you could also still use it as an "unevaluated component" under your Appendix B procedure. That said, 9 out of 10 UL inspectors know the INTENT of the rules and will accept a device that is UL listed under a different category as long as it is used in an appropiate manner consistent with the overall 508 standard. This guy is the 1 out of 10 that is being a stickler. I've had that happen on other things like panel mount Automatic Transfer Switches, which are UL1008 listed because they HAVE to be. UL1008 however is NOT on the list of acceptable standards within 508, so I have had Richard head UL inspectors bounce me on that one too, while others look at it and say OK.

 

[ramjr]

tooth fairy

tooth fairy

Thanks for the reply. I like to do the right thing but when it's out of your control you have to do what the Boss dictates. We removed the UPS and now call it a user accessory supplied by the owner. Although this meets UL requirements it does not address the acceptable use of a UPS in a control panel. Maby the tooth fairy has the answer. I'll put a $.25 under my pillow and wait for the answer!:lol::rant:

 

[Jraef]

I just looked at the 2010 version of UL508, still not there.

 

[Jraef]

Just a little follow-up, for what it's worth.

I had a buddy at Allen Bradley check into it for me. Turns out that UL1778 does make mention of being applicable to be used in control panels and references UL508A, but apparently this is an oversight at UL in that it is not receiprocal, meaning UL508A was never ammended to add UL1778 as acceptable. A-B has asked UL for clarification and they have said that it IS OK to use a UL1778 listed UPS inside of a UL508A custom control panel, stating some kind of procedural exception. A-B is planning on issuing a White Paper to that effect which will spell out the UL1778 mention of UL508A acceptability and whatever it is UL said was this procedural exception.