Ul 508?
- Thread starter eetwo
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charlie
Senior Member
- Location
- Indianapolis
The answer is a definite maybe. It is up to the AHJ in your area. :smile:
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
UL508A is a maybe.
NEC 409 is a definite. You will need to provide a label and an SCCR.
NEC 409 is a definite. You will need to provide a label and an SCCR.
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
This is a case where nuance and semantics come into play.
First the easy part; check with the local AHJ?s documented requirements. Many local jurisdictions will require listing ? even if the NEC doesn?t. Also consider any Local or Federal OSHA rules. In general, FedOSHA says if a product can be listed, it must be. See 29 CFR 1910.399 ? Definition of Acceptable, Part (1). Interpret it in light of the first sentence in Part (2). You may need to read it a few times, it is rather convoluted IMO.
Now - the semantic part. It depends on whether what is constructed is a Motor Control Center or a Motor Control System. They are evaluated under two separate UL Standards; 845 and 508A respectively. They don?t reference each other in the editions I have readily available and I doubt they ever will. The NEMA MCC folks want to be independent of most NEMA Industrial Control Systems (ICS) requirements. It can get messy because the NEMA MCC Standard does cross reference several ICS Standards.
NEC Article 430, Part VIII is the ?official? NEC MCC Section. Marking requirements are limited to those of Section 110.21. Listing is not a requirement.
A Motor Control System would typically fall under Article 409. See the definition of Industrial Control Panel in 409.2. The marking requirements in Section 409.10 do not actually require listing; however, ?listing? is one of the recognized methods of determining short-circuit ratings. The ?alternate? method more or less sends you back to UL 508A.
First the easy part; check with the local AHJ?s documented requirements. Many local jurisdictions will require listing ? even if the NEC doesn?t. Also consider any Local or Federal OSHA rules. In general, FedOSHA says if a product can be listed, it must be. See 29 CFR 1910.399 ? Definition of Acceptable, Part (1). Interpret it in light of the first sentence in Part (2). You may need to read it a few times, it is rather convoluted IMO.
Now - the semantic part. It depends on whether what is constructed is a Motor Control Center or a Motor Control System. They are evaluated under two separate UL Standards; 845 and 508A respectively. They don?t reference each other in the editions I have readily available and I doubt they ever will. The NEMA MCC folks want to be independent of most NEMA Industrial Control Systems (ICS) requirements. It can get messy because the NEMA MCC Standard does cross reference several ICS Standards.
NEC Article 430, Part VIII is the ?official? NEC MCC Section. Marking requirements are limited to those of Section 110.21. Listing is not a requirement.
A Motor Control System would typically fall under Article 409. See the definition of Industrial Control Panel in 409.2. The marking requirements in Section 409.10 do not actually require listing; however, ?listing? is one of the recognized methods of determining short-circuit ratings. The ?alternate? method more or less sends you back to UL 508A.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
In Washington, probably yes it has to be listed, but you can make it out of listed components and have it inspected, thats OK. But some components are not listed, only recognized.
But I have made many control panels and had them inspected as well. I know from experience that a UL508 shop can build them for the same cost as I can when I figure in my time. Why? because they get a much better discount on parts from AB, Square D etc than I do.
Plus a UL508 panel comes with a wiring diagram.
Plus are you familar with the SSCR requirements for branch circuit fusing, wire sizes, colors?
And even something as simple as wire type, the best wire is TEW. Most homemade use THHN which is harder to work with.
Well at least get a price from a UL 508 shop.
But I have made many control panels and had them inspected as well. I know from experience that a UL508 shop can build them for the same cost as I can when I figure in my time. Why? because they get a much better discount on parts from AB, Square D etc than I do.
Plus a UL508 panel comes with a wiring diagram.
Plus are you familar with the SSCR requirements for branch circuit fusing, wire sizes, colors?
And even something as simple as wire type, the best wire is TEW. Most homemade use THHN which is harder to work with.
Well at least get a price from a UL 508 shop.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
This is the best answer really. Many states have their own Electrical Codes. In it, they adopt a specific version of the NEC, then add their own provisions. For example here in California, we have the California Electrical Code, which just last year finally adopted the 2005 NEC.
Some states, and as far as I know ALL of the states west of the Rockies, add in a specific requirement for "NRTL* listing" on any assembly with more than "X" number of devices in it. Some it is 5 devices (counting the box itself), some it is as low as 3. So if you have a motor starter in a box (contactor, OL relay, box), that's OK. But a motor starter, breaker, CPT, HOA and a Pilot Light will require an overall NRTL listing for the entire assembly. Now most motor control manufacturers' UL listing will include their own specific factory mods within the listing of the starter, and you can tell what they are by looking at their UL file on UL.com (assuming you know the file number). So for instance A-B will have a single listing covering a NEMA 1 enclosed starter with whatever brand of breaker it was listed with (Eaton in their case), their starter, their OL relay, their CPT and their pilot devices. But if you have an A-B starter, a Siemens breaker, Square D pilot devices and a Micron CPT, that combination of devices will not be in the A-B starter's UL file, so you are on your own again. The same would be true in fact if you used some pilot devices, even if A-B's, that were NOT specifically listed in the UL file for that starter. It can get a bit tricky and some AHJs are very well versed in this issue. I know from when I worked in Seattle that the inspectors there were very savvy. Alaska too. Here in California it's kind of a crap shoot; some are savvy, some don't seem to care much, but you can never tell in advance which one you will get (and sometimes it's the same guy on different days).
*NRTL stands for Nationally Recognized Testing Lab, of which UL is the most widely known, But there are a number of other alternatives, and each jurisdiction that requires NRTL listing will also have a list of labs that they accept. Pretty much all of them accept UL and ETL, so those are essentially the "no brainers".
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