Sort of...
NEC Article 551 covers ‘line voltage” systems on RVs. But excludes DC circuits of the vehicle. I will guess those are covered by SAE and probably others such as DOT.
NFPA 1192 which covers all sort of RV systems. Probably has an elecrical chapter.
As aside, As its fairly recent development and never had to deal with professionally, I dunno what NEC or NFPA have to say about highvoltage traction systems of electric vehicles.
The NEC tells us their intention...
90.2 Scope.
(A) Covered. This Code covers the installation of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways for the following:
(1) Public and private premises, including buildings, structures, mobile homes, recreational vehicles, and floating buildings
(2) Yards, lots, parking lots, carnivals, and industrial substations
(3) Installations of conductors and equipment that connect to the supply of electricity
(4) Installations used by the electric utility, such as office buildings, warehouses, garages, machine shops, and recreational buildings, that are not an integral part of a generating plant, substation, or control center.
(B) Not Covered. This Code does not cover the following:
(1) Installations in ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles
Informational Note: Although the scope of this Code indicates that the Code does not cover installations in ships, portions of this Code are incorporated by reference into Title 46, Code of Federal Regulations, Parts 110–113.
(2) Installations underground in mines and self-propelled mobile surface mining machinery and its attendant electrical trailing cable
etc, etc, etc
I think alot of people use ampacity tables from NEC as they are abundantly published, and fairly conservative values.
They are conservative but for smaller gauge (I'd say up to around 10 or 12 AWG or so) wire that's fine and in reality even if you do all the calcs yourself you'll probably arrive at about the same place as the NEC charts.
It's when you get larger than about 8 AWG and certainly by around 4 AWG or so the NEC approach makes less sense with respect to vehicles. They are coming from a standpoint that if you're hanging heavy cable it's because you're probably wiring a factory or substation but you're just doing intermittent use of a winch on a truck. That's not to say there's not overlap, such as supplying the DC-side of an inverter.
If you adhere to their capacity charts you'll end up with 1/0 where 2 AWG is very likely acceptable for your heating expectation. So while you err on the side of safe using a size or two larger you can factor in weight and cost to see what you *really* need. Which is where you'll find the...
OEM is a good starting point so long as you know what the limits the manufacture designed it for.
They follow down to the decimal point circuit capacity in current and time. They don't want to have you carry around one gram more copper and PVC than the circuit requires as the cost is MPG and profit for them. The main thing to understand is the OEM (SAE) was interested in being just safe enough when building millions of widgets.
So when we do our work we have to find a sensible balance between the two approaches. We're not bound by the need to gram shave like they did but being ultra conservative still has an impact on our space and money budgets.