Labeling equipment - how many?

Hugh Hoagland

Staff member
Dec 30, 2016
Louisville, KY
The NEC and NFPA 70E require the following:
  • Switchboards
    Industrial Control Panels
    Meter Socket Enclosures
    Motor Control Centers

and electrical equipment… “likely to require examination, adjustment, servicing or maintenance while energized shall be field-marked with a label…” NFPA 70E 130.5(D)

David Ng

New Member
Feb 14, 2019

Are 120VAC panels required arc flash label or just shock hazard labeling.? The IEEE-1584 equations does not go beyond 208VAC. We were told that these panels has to be labeled since there is potential of phase to ground fault. In this case, can a plant use both the IEA method for 480-208VAC and the tables for 120VAC single phase panels.? I always though that phase to ground in a a120VAC system would be a ground fault but have seen in some instances where an "arc" or "Spark" would occur but not sustained. I think using both methods in a plant may confuse people. Any suggestions would be appreciated.

Thank you.

Firstly, sorry that we missed this comment. We migrated servers and some content was affected by the move to a more secure system.

The IEEE 1584 WG is only now looking at the impact of single phase. It is a new project and the research budget is very limited which influences the timeline. A system is only considered a single phase circuit if the ENTIRE panel only has a single phase (out of three) into the panel and the associated neutral and ground wires. On the other hand, if you only have all single phase breakers, but the panel bus is three phase, that system will be considered three phase and should be labeled for both shock and arc flash. Single phase does not have to be labeled with arc flash at this stage (no standard in place), but the SHOCK hazard MUST be indicated.