National Electrical Code

Temporary Installations and the NEC

Nov. 20, 2018

Do you know the requirements surrounding temporary installations?

With temporary installations, “temporary” is a time concept, not a quality concept. Temporary wiring must be removed immediately upon completion of the construction or purpose for which it was installed [Sec. 590.3(D)] and temporary wiring for holiday lights must be removed within 90 days of installation [Sec. 590.3(B)].

Even if temporary:

Services must comply with the applicable Parts I through VIII of Art. 230 [Sec. 590.4(A)].
Feeders still require Art. 240 overcurrent protection [Sec. 590.4(B)].
Branch circuits must originate in an approved power outlet, switchgear, switchboard, or panelboard [Sec. 590.4(C)].
Receptacles must be of the grounding type [Sec. 590.4(D)] and if on construction sites cannot be installed on any branch circuit that provides temporary lighting

Suitable disconnecting switches or plug connectors must be installed to permit disconnecting all ungrounded conductors of each temporary circuit [Sec. 590.4(F)].

Flexible cords are typically present on jobs that require temporary wiring. These must be protected from accidental damage [Sec. 590.4(H)]; using a combination of cord protectors, proper supports, and smart routing will achieve this.

About the Author

Mark Lamendola

Mark is an expert in maintenance management, having racked up an impressive track record during his time working in the field. He also has extensive knowledge of, and practical expertise with, the National Electrical Code (NEC). Through his consulting business, he provides articles and training materials on electrical topics, specializing in making difficult subjects easy to understand and focusing on the practical aspects of electrical work.

Prior to starting his own business, Mark served as the Technical Editor on EC&M for six years, worked three years in nuclear maintenance, six years as a contract project engineer/project manager, three years as a systems engineer, and three years in plant maintenance management.

Mark earned an AAS degree from Rock Valley College, a BSEET from Columbia Pacific University, and an MBA from Lake Erie College. He’s also completed several related certifications over the years and even was formerly licensed as a Master Electrician. He is a Senior Member of the IEEE and past Chairman of the Kansas City Chapters of both the IEEE and the IEEE Computer Society. Mark also served as the program director for, a board member of, and webmaster of, the Midwest Chapter of the 7x24 Exchange. He has also held memberships with the following organizations: NETA, NFPA, International Association of Webmasters, and Institute of Certified Professional Managers.