How to Wire a New 50-amp Generator into a 30-amp RV
Wiring a larger 50-amp generator into your 30-amp RV will provide more power for additional appliances in remote campgrounds. Before you can enjoy this extra power in the great outdoors, you need to install a transfer switch, add a circuit breaker panel and complete some rewiring.
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Things You'll Need
- Wire stripper
- Power screwdriver
- Flat screwdriver bit
- Phillips screwdriver bit
- Wire cutter
- 10/2 cable
- 6/3 generator power cable
- 6/3 shore-power cable
- 50-amp automatic transfer switch
- Circuit breaker panel
- Electric drill
- Drill bits
- #10 mounting screws
Instructions
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1
Mount a new circuit breaker panel. Find a location to install the new circuit breaker panel, preferably close to the existing one. Drill four 9/64-inch mounting holes. Secure with #10 screws.
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Install the transfer switch in a place away from any flammable or explosive fumes. Drill four 9/64-inch mounting holes and secure with #10 screws. Ensure the mounting surface is strong enough to hold the weight of the transfer switch during the operation of the RV.
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3
Wire the generator cord to the transfer switch. A 50-amp RV generator has a four-wire, 240-volt system that needs a 6/3 cable---a cable that has six-gauge wire with three conducting wires plus a ground wire.
The top hole of the generator outlet is the ground terminal; it has a green wire connected to it. The left hole is a hot terminal; it has a red wire connected to it. The right hole is also a hot terminal; it has a black wire connected to it. The bottom hole is the common terminal; it has a white wire connected to it.
If you measure the voltage between the red wire and the white wire, you will get 120 volts. If you measure the voltage between the black wire and the white wire, you will also get 120 volts. If you measure the voltage between the red and black wires, you will get 240 volts.
Strip a 1/2-inch of insulation from each of the four wires in the generator power cord.
Pass the cable through the transfer switch case cable clamp opening; do not tighten it yet.
Unscrew the setscrew for each of the four wires. Install the wires as instructed by the manufacturer's label. The red and black wires are interchangeable---it does not matter if you switch them.
Tighten the setscrew for the wire to 20-inch-pounds. Tighten the cable clamp.
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4
Connect the four-wire end of a 6/3 50-amp shore-power cable to the transfer switch. Each transfer switch manufacturer will have a unique set of instructions; follow their instructions.
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Connect a 10/2 cable between the transfer switch and the new circuit breaker box. This cable will carry 120 volts from the transfer switch to the new circuit breaker box. Do not bond the neutral and ground wires at the circuit breaker panel; keep the white and green wires separate.
In an RV, if the green and white wires are bonded like they are in a house, anyone touching the RV will complete the circuit to ground and possibly get a lethal dose of electricity if a short circuit occurs.
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Connect a 10/2 cable between the transfer switch and the old existing circuit breaker box. This cable will carry 120 volts from the transfer switch to the original RV circuit breaker box.
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7
Wire new appliances to the new circuit breaker box. Keep the load on the two circuit breaker boxes balanced. Move circuits from the old box to the new box if necessary.
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8
Turn off the RV circuit breakers. Connect the shore-power cable to an RV outlet. Test for power by turning on a circuit breaker. The transfer switch will give priority to shore-power---it will disconnect generator power when there is shore-power available.
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Turn all the circuit breakers off. Plug the generator cable into the generator and start it up. Flip a circuit breaker to the on position to test for proper operation. You should never start a generator with a load on it.
Connecting a new 50-amp, 240-volt generator to your old 30-amp RV is not a mystery if you remember that a 50-amp, 240-volt circuit is just two 120-volt circuits side by side.
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Tips & Warnings
Install the new circuit breaker with an isolated neutral.
Check the old circuit breaker for an isolated neutral.
Ensure the power supplies are turned off before working on the RV circuits.
Remember that if your RV has an inverter, it too can be a deadly power supply. Turn it off before performing installations.
References
- Photo Credit rv image by Greg Pickens from Fotolia.com
