Temporary Installations

by Jeff Keljik
Director of Training

Article 590 applies to the temporary installation of electric power and lighting. We are obligated to make sure that temporary wiring does not become permanent wiring, which we may see in our casual observations of some locations. That means the time constraints of Art 590 allows some leniency in the requirements when the wiring is used during the time of construction, remodeling, maintenance or demolition of the building. Temporary wiring can also be used for up to 90 days for use in holiday decorative lighting or similar purposes. (It seems that we are usually within 90 days of a holiday!) The temporary wiring can also be used for emergencies or for testing such as for experimental or development work. The stipulation for all these cases is that the wiring be removed at the culmination of the event.

A few changes have been included in the 2017 code Article 590. When using wiring for feeders, you may use cords of hard or extra–hard usage. In the 2017 NEC, type SE cable can be installed in raceways underground in temporary situations. NM and NMC is also permitted in any dwelling, building, or structure without regard to height as long as they are not concealed within walls, floors or ceilings. The same requirements and permissions apply to branch circuit wiring. For wiring receptacles, be sure they operate as grounded receptacle and they are not on the same branch circuit as the lighting outlets. If the receptacles are in wet locations, they must have a weatherproof enclosure and be protected by an “extra-duty” box hood or equivalent. Multiwire circuits are permitted as long as the disconnecting means disconnects all ungrounded conductors simultaneously.

Where splicing conductors, a box is normally required. On temporary wiring applications, a box is NOT required under two conditions:

(1) The conductors are all from a non-metallic wiring system and the grounding conductors’ continuity is maintained, or

(2) if the conductors are from a metallic cable, the listed cable fittings maintain the electrical continuity of the metal sheath. One more chance to 2017 allows a SPGFCI to be used for GFCI protection.