enblethen wrote:
I would suggest replacing the feed to the garage and then installing the RV receptacle off that.
You could use RHH/RHW/USE wire which is rated for direct burial. I would use #6. Yes, slightly overkill(50 amp). yes, #8 would work(40 amp).
The ground wire can be smaller. It would be calculated on the amperage of the circuit breaker in the source panel. A #10 ground wire would be sufficient for up to 60 amp circuit breaker.
I would install and additional ground rod at the detached garage for a little extra protection.
I agree with enblethen. Except I would run 3 #3awg copper or #1awg aluminum and a #5awg ground to install a 100Amp sub panel in the garage. This will provide branch circuits for a single phase 30A RV outlet, 50A 2-phase RV outlet, 8hp air compressor, and more 20A outlets in the garage. Can't have too many outlets!
Also, oversize the PVC conduit. It's pretty cheap. I ran 3 runs of 1.5" PVC for power, air hose, and communications from my service panel location in my attached garage to my pole bldg. Justify the material costs by doing the work yourself and saving thousands in labor.
