NEC Code book Clarification for UPS
- Thread starter RRoc
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- Location
- Bremerton, Washington
- Occupation
- Master Electrician
it’s more likely a UL508A issue. It’s common to see a UPS sitting in the bottom of a control panel with cords and plugs, I don’t have UL508A to know if that was allowed, but likely not.
I used a UPS made for AB by APC. It was DIN rail mounted with wiring terminals, UL listed.
Later we switched to all 25VDC controls and used a 24VDC ups from AB. It avoided the 120 to 24 vdc into the ups, 24 vdc to 120, and then back to 24 vdc in the plc. Way more efficient, went from 3 hrs battery on ups to days. All the AB 24 vdc ups and batteries are ul listed, our inspectors look for that
I used a UPS made for AB by APC. It was DIN rail mounted with wiring terminals, UL listed.
Later we switched to all 25VDC controls and used a 24VDC ups from AB. It avoided the 120 to 24 vdc into the ups, 24 vdc to 120, and then back to 24 vdc in the plc. Way more efficient, went from 3 hrs battery on ups to days. All the AB 24 vdc ups and batteries are ul listed, our inspectors look for that
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
My experience with control panels is in Washington state. If a job had an industrial control panel, the inspector would open the door and look for the green UL label. If the label was there, he would just look at the field terminations for the input in the output wiring. If there was no label the job stopped. Inspector wasn’t concerned with what was in the panel as it was covered by UL 508 and the system integrators following the UL requirements. If your control panel with the UPS is not required to be listed by your AHJ, then you won’t find much in the NEC to cover that. There is an article 509 in the NEC that covers industrial control panels, but in Washington state or inspectors do not use that.
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