When working inside confined spaces must electrical lighting circuits be seperate form all other electrical circuits? Where in the NEC is this subject addressed?
The NEC does not directly address confined spaces. The OSHA 1910 and 1926 Standards will address the requirements. A crawl space could be defined by OSHA as a confined space. The branch circuit requirements for crawl spaces can be found in 210.8(B)(9) and (E) and requires GFCI protection for the receptacles and lighting outlets. The NEC does not prohibit a single branch circuit from supplying the receptacles and lighting outlets.
The National Electrical Code (NEC) Section 590.4(D) prohibits any receptacle on branch circuits that supply temporary lighting on construction sites. Electrical faults from other electrical equipment on the lighting circuit could trip the circuit leaving workers in the dark which could create safety hazards.
Note that OSHA references the NEC in their respective standards.
NEC does not define nor address confined spaces. If it is temporary wiring on a construction site, then it would be covered under the Article for temporary wiring (590), as you pointed out.
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