A Tiny House on Wheels should be wired similarly to an RV. Since tiny houses don't typically hang out at RV parks, but rather on properties situation near a main house, it is useful to design your system to be able to accept either 15-amp, 20-amp or 30-amp service based on your current location and immediate needs. [RVs typically use either a 30-amp (120vac) or 50-amp (240vac) service.] If you need more than a 30-amp service, see the links at the end of this page for more information.
It is imperative to know what your power needs are, so always take an inventory of the amperage and volts needed to supply your house.
Designing a system to accept either 15-amp, 20-amp or 30-amp service is quite simple. Note that, based on what service you are currently pulling from (15-amp, 20-amp or 30-amp), you will have to adjust the power usage in your house.
This is a 30-amp RV plug (TT-30):
And this is the 30-amp to 15/20-amp adapter:
So, either inside or outside your house on wheels, you'll have a sub-panel (meaning that the neutral and ground bars are separated). For ease of moving and hooking up power, I recommend the following: On the outside of the house, install a TT-30R, which looks like this -->Wire this receptacle to your sub-panel's hot, neutral and ground bus. This is the way of your incoming power.
Now, your 30-amp RV plug needs a wire/cord. The size of the wire will depend on the length of the wire or the distance from your house to the power source. Use this table to guide which size wire to use:
| For 120 V | 15 amp | 20 amp | 30 amp | 50 amp | 100 amp |
| 25 feet | #14 | #12 | #10 | #8 | #6 |
| 50 feet | #12 | #10 | #8 | #6 | #4 |
| 100 feet | #10 | #8 | #6 | #4 | #1 |
Always err on the side of a larger (i.e. lower number!) wire gauge! And of course make sure the cord is rated for outdoor use. I always have a few different cords/gauges on hand for different situations.
As for wiring the inside of your house, it is wired as any other house is. 12 AWG (gauge) wire should be used throughout the house for all 20 amp circuits. Never use a 14 gauge wire with a 20 amp circuit breaker. Refer to the books Wiring Simplified and Wiring a House for further information on wiring house receptacles and panels.
More Resources:
How to Wire an RV Receptacle:
http://www.myrv.us/electric/