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National Electrical Code Articles and Information

Based on the 2020 NEC

by Mark Lamendola

National Electrical Code Top Ten Tips: Article 551, Recreational Vehicles and Recreational Vehicle Parks. Part 1.

  1. Article 551 defines "recreational vehicle" as a vehicle-type unit used as temporary living quarters for recreational, camping, or travel use. The four basic entities are travel trailer, camping trailer, truck camper, and motor home [551.2].
  2. An RV not used for the purposes stated in 551.2 doesn't need to comply with the requirements for the number or capacity of circuits. It must, however, comply with all of the other requirements if it has a power source that is 120V, 120/208V, or 120/240V [551.4].
  3. You must bond the voltage converter enclosures with a minimum 8AWG copper conductor [551.20(C)].
  4. You cannot use autotransformers with RVs [551.20(E)].
  5. Part III provides the requirements for providing power to an RV from sources other than 120V, 120/208V, or 120/240V systems [551.30 - 33]. Typically, this means a generator.
  6. If you use a generator, it must be bonded to the RV chassis [551.30(A)]. This bonding requirement actually applies to all power sources. The point of it is to prevent a difference of potential.
  7. For 120V, 120/208V, or 120/240V systems, you must provide GFCI [551.40].
  8. Each RV must contain one of the three branch circuit arrangements detailed in 551.42(A) though (D).
  9. The working clearance for the panelboard must be at least 24 inches wide and 30 inches deep [551.45(B)]. This limits where you can place the panelboard. In addition to structural considerations, factor in storage. You don't want to locate the panel where someone is likely to store combustibles or other materials.
  10. The point of entrance of a power supply assembly must meet specific requirements, which are detailed in 551.46(E). These include, for example, that it must be within 15 feet of the rear and to the left of the longitudinal center of the vehicle.