The 2020 Edition of the National Electric Code says in 90.2(A)(1) that its scope covers recreational vehicles. However, when looking at 551.2, it defines a recreational vehicle as, "A vehicular-type unit primarily designed as temporary living quarters for recreational, camping, or travel use, which either has its own motive power or is mounted on or drawn by another vehicle." So, a camper van, skoolie, overnight bus, houseboat, yacht, cruise ship, overnight train (such as Amtrak), wide-body airliner, private jet, and long-haul tractor of a semi-truck are also an RV under the definition of the NEC 2020 because they are all vehicles with permanent provisions for sleeping beds and washrooms, making them each a temporary living quarter for travel use. However, none of these are listed as definitions under 551.2, and the non-road vehicles are in direct contradiction with 90.2(B)(1), where "Installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles do not apply." Since the NEC does not give higher hierachy to either the "covered" list or "not covered" list, it is ambiguous whether or not RVs take precedence over non-road RVs for compliance purposes. So, are non-road vehicles "primarily designed as temporary living quarters for recreational, camping, or travel use" covered by the scope of the NEC 2020 or not?


Also, 551.1 says that the scope of Article 551 excludes low-voltage and automotive circuits and extensions thereof on RVs. So, are those circuit only exempted from Article 551, or are they exempted from the entirety of the NEC 2020?

Also, would a 120V 60HZ circuit in an RV that is connected via an inverter exclusively to the on-vehicle batteries that is charged via mains electricity (like NEMA sockets that are factory-installed into EVs and PHEVs) count as an extension of an automotive circuit, thus excluding it from the scope of Article 551?

If that circuit had a switch to bypass the battery system to be able to connect to the mains electricity directly, would the circuit need to comply with the NEC when it's unplugged from the mains electrical supply?