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Control Panel Requirements: UL508A & NFPA 79

Control Panel Requirements: UL508A & NFPA 79

NEC articles 90.7 and 110.3 make it clear that electrical equipment must be "suitable," and the best way to indicate suitability of a control panel is via third-party listing. In the US, that typically means UL508A listing. As I read Article 409, UL508A listing isn't explicitly required. It's just one option.

But what if the control panel will be installed as part of a piece of industrial machinery as defined in Article 670.2? Does this then mean that the control panel construction must follow the requirements in NFPA 79 as well? Or does NFPA 79 just govern the installation of these control panels? It's not clear to me if NFPA 79 is mandatory, and if so, when. Any thoughts?


RE: Control Panel Requirements: UL508A & NFPA 79

UL508A - Here is UL in a nutshell. If you order all parts in your panel as UL listed. UL also specifies any heat producing components have proper spacing. I would also have the panel built by a UL listed shop, then you can have the added sticker on the panel as UL listed by panel shop. If you UL list your panel and sell into USA then its a lot easier for a local electrical inspector to sign off on the local installation. You also have UL listed sub assemblies which is another discussion where UL sticker was given to a manufacturer on a product line when multiply components are used together.

NFPA 79 is also a standard for machinery with control panels. I think when i was doing unit operation machines that this was a kind a of bible. I would review this document if this is the case for requirements.

I think if you comply with both docs then your job at the far end during project sign off will be a lot easier.

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