myredracer wrote:
Whether or not you plan to run the AC unit, or two of them, will make a big difference in sizing the wiring as opposed to just running the converter/charger and fridge. While #10 may have the required min. ampacity per code, you should consider voltage drop which in a branch circuit (the 30 amp RV outlet in this case) has to take into account the total overall length of the conductors - from the house panel to the 30 amp receptacle, the length of the shore power cord + extension cord, and the length of the romex inside the RV from point of entry to the RV's panel. As well, you need to know what the voltage at the supply end of the 30 amp circuit is, ie. the voltage at the house panel.
It is especially important for RVs to reduce voltage drop when using AC units because as voltage goes down, they draw more current. And as current goes up, the increased current causes even more voltage drop. If the voltage gets too low, it can damage AC units and it will happen over time.
Another factor is providing sufficient voltage for AC units during the momentary starting inrush current. This will be listed as "locked rotor current" in the AC manufacturers data. Inrush current will be as high as 5-6 times the running current and if the overall wire length of the the 30 amp circuit is too long and the gauge too small, it will not allow the AC unit to start and a 30 amp breaker can trip. If you do manage to get the 1st AC running, getting a 2nd to start may not be possible and can trip a 30 amp breaker. Sometimes the 20 amp breaker in the RV's panel will trip.
Unless you do a detail voltage drop calc. and can show that #10 is adequate, I would go with min. #8 wire for wire to the recept. A #8 extension cord might be needed. #6 may even be the right thing to use. There are a number of wiring methods that could be used (romex, wire in conduit, armored cable, etc.) and would depend on the material costs and labor costs (if applicable).
I highly recommend installing a disconnect switch at the 30 amp RV recept. so that you won't be plugging in live (which is bad for the plug and recept. contact surfaces). A single breaker in an enclosure will work and a "motor rated" toggle switch will also work.
Forget about using the pump wiring as the wire and overcurrent device will have been sized for just the pump plus tapping into the circuit will likely not comply with the NEC.
It looks like an 8 or 6 gauge is required if I plan to be using a 100ft extension to the RV from the Receptacle.
Use a 6 gauge from the panel to the receptacle (very short distance....a few feet at most).
use an 8 guage extension from the receptacle to the RV?
