NEC Article 520 deals with the electrical protection of movie theaters & studios. Learn more about the mandated ground fault protection of these environments.

National Electrical Code Article 520 details the mandated electrical safety requirements to view motion picture projection, musical, and theatrical performances in both indoor (movie theaters, screening studios, playhouses, etc.) & outdoor (amphitheaters, music centers, performance areas, etc.) locations. This Code mandates wiring methods, the correct use of portable equipment (x. stage lighting), switchboard compliance, and more. One subsection, NEC 520.9, explains what ground fault protection standards these locations need to follow.

This subsection’s intention is to inform about the correct use of branch circuits for electrical systems in theater locations. It notes that the voltage rating of the receptacles need to be at or above the circuit's voltage & amperage. It also states that these branch circuits need to follow NEC 210.8(B) regarding ground fault circuit interrupter (GFCI) protection. This means that all 125-volt and 250-volt receptacles supplied by single-phase branch circuits up to 50 Amps, and all receptacles supplied by three phase branch circuits supplying up to 100 Amps need Class A (5 mA +/- 1 trip level) ground fault protection.

National Electrical Code Article 520 makes sure that patrons and workers of theaters are safe from electrical harm. It also notes, like a lot of other NEC Articles, that these areas need to follow NEC 210.8(B) and provide Class A GFCI protection for their electrical equipment.