RVer asks about plugging 30 amp RV into 50 amp service

A question from an RVtravel.com reader to Gary Bunzer, the RV Doctor.

Dear Gary,
Our motorhome has 30 amp service. We’ll be camping in the near future but the site has 50 amp service. I have a 50 amp to 30 amp dogbone adapter but a 30-amp surge protector. Can I place the surge protector after the 50 amp to 30 amp dogbone before plugging in my RV service? — Joe from Nebraska

Hello, Joe,
Yes, you can plug into shore power like you’ve suggested. But typically, if there is 50-amp service available there is also a 30-amp receptacle as well. If you’re sure the pedestal will only be equipped with a 50-amp receptacle, it is quite okay to reduce that to the 30-amp required by the motorhome. And yes, the surge protection would be inserted between the coach and the adapter.

But do check and look for a 30-amp receptacle first. The fewer mechanical connections (plugs), the better. With 50-amp service, you will be connected through only one leg of the incoming 240-volt electricity and the surge protector will only be seeing one leg of 120-volts AC since it will be plugged directly into the 30-amp side of the dog bone reducer.

You will be fine. The coach will be limited to 30-amps max. Do measure the voltage before plugging anything into the shore power to verify it is wired correctly. Here’s how it should measure:

•120-volts AC (+/- 5%) between the ground pin and each leg of the incoming voltage.
•120-volts AC (+/- 5%) between the neutral conductor and each leg of the incoming voltage.
•0-volts AC between the ground pin and neutral conductor.
•240-volts AC between the two hot legs. If you measure 0-volts between the two hot legs, do not plug anything in! That means they are both wired to the same phase.

Hope this helps!

Follow Gary at his blog, the RV Doctor.