I have a Thor Hurricane M35. The microwave outlet is dead, but all other electrical outlets still work. Where do I start to locate the problem? GFIs have not tripped. Any help will be appreciated. Thank you. —Fred
Typically the outlet for the microwave would not be “ganged” to a Ground Fault Circuit Interrupter, rather a dedicated wire from the distribution center to the outlet. Below is a diagram from a Winnebago motorhome that has a similar distribution center and shows wiring for the microwave and the other outlets.
It might be hard to see; however, the microwave outlet is a dedicated 15-amp circuit breaker with a 14-2 wire coming off it. The wire goes to a 110-volt connection under the galley, then to a 110-volt connection under the stove, and then to the microwave outlet labeled RCP-2. No GFCI in the circuit!
Also on this load center is a 15-amp circuit breaker with 14-2 wire. This wire goes to a GFI-1 outlet in the bathroom, ganged to RCP-2 exterior, then goes to 110-volt connection under the right front room, then to 110v connection under the dinette, and finally to RCP-3 at the dinette.
Troubleshooting the dead microwave outlet
First, I would start with a Ground Fault Circuit Interrupter tester plugged into the outlet to verify if it has power or not. You can use a simple one available at any home improvement store or even Harbor Freight. I got mine at Home Depot.
Test the outlet to make sure it does not have power. If it does, then you have an issue with the microwave. If it does not have power, use a non-contact voltage tester to see if there is any voltage to the outlet. The non-contact voltage tester will indicate power within a 6″-8” distance so a wire could be disconnected but still show voltage. If this is the case, shut off the circuit breaker at the distribution center and pull the outlet out to inspect the wiring.
Assuming there is no power to the outlet, check the circuit breaker at the distribution center. You will probably not be able to use the non-contact voltage tester as it will indicate voltage from a close breaker, so that would need to be conducted with a multi-meter. However, you should be able to locate the wire coming off that circuit breaker and follow it with a non-contact voltage tester. As shown above in the Winnebago example, you might have a junction box in-line that could also be the issue. Using the tester, you can verify if there is power going to the junction box and then to the outlet.
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
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