This is a basic question, but I cannot seem to find the answer in the NEC; it is not clear to me.
I know that over current protection is needed for an assembly and is typically put within the assembly at the incoming AC, but where does it state it is required in the NEC for such an assembly comprised of a 4X enclosure with din-rail mounted modules (Power supply, SBC, I/O modules, comm module. It would be powered off 120V, 60Hz, single phase, used on a drilling rig. It would have signal I/O cables attached to it. The locations of installation for discussion sake could be an ordinary location (non-hazardous) area or a Class I, Div 2 area.
I see treatment on the topic of overcurrent protection in article 240, and there are numerous specific examples of where overcurrent protection is required but I not see a description that would include this assembly. I see discussions regarding feeders, branch circuits, taps, and it seems that this applies to what is upstream from an electrical outlet receptacle where this assembly would plug its power cable into.
The electrical safety standard that would be used to assess this assembly would not be UL 508A, but rather UL 61010-1. It is not an industrial control panel.
Within the standard in 9.6.2, regarding "permanently connected equipment" (requiring use of a tool to disconnect), "overcurrent protection devices are optional, and if none are fitted, the installation instructions shall specify the characteristics of the overcurrent protection devices required in the building installation."
If "other equipment" per 9.6.3, "if an overcurrent protection device is provided, it shall be within the equipment."
It would seem that UL standards should be in alignment with the NEC, and overcurrent protection for such an assembly be found in the NEC whether within the enclosure or without; i just can' find what I'm looking for.
Any help is much appreciated.
Thank you
I know that over current protection is needed for an assembly and is typically put within the assembly at the incoming AC, but where does it state it is required in the NEC for such an assembly comprised of a 4X enclosure with din-rail mounted modules (Power supply, SBC, I/O modules, comm module. It would be powered off 120V, 60Hz, single phase, used on a drilling rig. It would have signal I/O cables attached to it. The locations of installation for discussion sake could be an ordinary location (non-hazardous) area or a Class I, Div 2 area.
I see treatment on the topic of overcurrent protection in article 240, and there are numerous specific examples of where overcurrent protection is required but I not see a description that would include this assembly. I see discussions regarding feeders, branch circuits, taps, and it seems that this applies to what is upstream from an electrical outlet receptacle where this assembly would plug its power cable into.
The electrical safety standard that would be used to assess this assembly would not be UL 508A, but rather UL 61010-1. It is not an industrial control panel.
Within the standard in 9.6.2, regarding "permanently connected equipment" (requiring use of a tool to disconnect), "overcurrent protection devices are optional, and if none are fitted, the installation instructions shall specify the characteristics of the overcurrent protection devices required in the building installation."
If "other equipment" per 9.6.3, "if an overcurrent protection device is provided, it shall be within the equipment."
It would seem that UL standards should be in alignment with the NEC, and overcurrent protection for such an assembly be found in the NEC whether within the enclosure or without; i just can' find what I'm looking for.
Any help is much appreciated.
Thank you
