By Tom Markel
Q: What are the considerations for safely wiring a tent?
A: In the United States, requirements for providing electricity are covered by the National Electric Code (NEC) 2008, also known as Article 70 of the National Fire Protection Association (NFPA), and adopted by states and local governments. The NEC deals with wiring and appliances using 1,000 volts or less. It guides installers, manufacturers and third-party testing organizations such as Underwriters Laboratories® (UL) and Factory Mutual (FM) as they develop standards. It is adopted by states and localities to become the bases for the code enforced by Authorities Having Jurisdiction (AHJ).
The NEC has general sections governing how to wire installations. For example, Article 250, which covers grounding and bonding of all electrical systems such as ones running on generators, affects events by requiring either 15 feet of separation between tents or apparatus powered by different sources (generators and/or utility) unless all the systems are grounded together.
Codes are subject to interpretation by the AHJ. The local AHJ can interpret the NEC to require all circuits be Ground Fault Circuit Interrupter (GFCI) protected because of the possible wet or outdoor location(s). This makes sense for a 20-by-20-foot tent in a backyard, but for a clearspan with a raised floor, it would seem to be an unnecessary requirement. The NEC and NFPA (101 Life Safety) codes also require installation of exit signs and emergency lighting be a non-GFCI source, the reverse of the other requirement. Ultimately, it becomes the AHJ’s call as to what variance it will or will not allow.
Articles 520 (Theaters, Audience and Performance Areas) and 525 (Carnivals, Circuses, Fairs and Similar Events) target the tent rental industry. Installations for events must use “rough service” copper and not aluminum conductors for any wiring and must use insulated conductors for grounds. Examples of rough service insulation suffixes are SJ, SO and SE, so household extension cords or Lamp Cord (SPT) wire cannot be used. In addition, Article 525 (NEC) forbids running power from one tent to another by supporting wiring in a previous tent. It also forbids using a tent to support single conductors (wires) such as #2, 4-ought or 800mm cables without grounding the entire tent. However, multiconductor wires such as extension cords (SJ and SO) or cables for lighting can be supported by the tent, again with rough service insulation jackets.
The NEC only allows temporary wiring to be installed for 90 days. Long-term tent installations (for more than 90 days) have to be wired with “permanent” wiring criteria. The other option is to remove all wiring after 90 days and then reinstall it. (But be aware: The clock starts ticking from the day installation begins.)
Adding some electrical and lighting capability can help your bottom line, but check with your local AHJ to determine what it will and will not allow, as this will vary between jurisdictions. Make friends with a local electrical contractor to help you with larger events or long-term installs. They can help get your electrical installation done right without as many hassles with the local AHJ.