I just rented a storage garage for our new Class A motorhome. It came wired with a 30 amp plug but it's one of the twist type plugs that are typically seen on generators. I purchased a 30amp to 50amp adapter from Etrailer. I took my multi-meter to the garage yesterday to test the plug. I think it is wired correctly but I wanted to make sure before I plug in my new 100K+ motorhome!If you are looking at the 50 amp plug, there are 3 vertical holes (one on top and two on the sides) and then one round ground plug. I believe the top hole is the neutral. Going from the top hole to one of the side holes, I get 117 volts. If I go from both the outside holes, I get 235 volts. I believe this is correct but can someone please confirm?Thanks,Burch

Yes that is correct. So in this case you will two legs of 30 amp power.

corvettekent wrote:Yes that is correct. So in this case you will two legs of 30 amp power.X2

That existing twist lock plug may not be wired the same as a 30 amp rv plug. Might be wise to get that changed now to an actual rv plug . 30amp rv is 115 volts & that twist lock might be 230 so your adapter may not work. Use a voltmeter.You are correct on the MH 50 amp.Buddy of mine is an electrician and a few weeks back went & corrected a miswired 30 amp plug that fried a brand new rig 1st time the owner plugged in. Who ever put it in wired it like a 230v plug.. The owner said he got a good deal on wiring his new storage barn for his new rig, lol

sayoung wrote:That existing twist lock plug may not be wired the same as a 30 amp rv plug. Might be wise to get that changed now to an actual rv plug . 30amp rv is 115 volts & that twist lock might be 230 so your adapter may not work. Use a voltmeter.You are correct on the MH 50 amp.I did use a voltmeter with the 30 amp to 50 amp adapter plugged into the twist lock 30amp plug. It measures two legs at around 117 volts. I can't change the plug since I am only renting the facility. I was a little surprised that the facility doesn't use a standard 30amp RV plug since their website says wired for 30 amp RV service. From the other responses, it sounds like it is wired correctly. My fear was plugging in and frying my brand new Class A's electrical system!Burch

MetalGator wrote:I just rented a storage garage for our new Class A motorhome. It came wired with a 30 amp plug but it's one of the twist type plugs that are typically seen on generators.I think you mean socket, not plug. I guess you don't get two hots - just one hot separated into two parts.

Wiring for 50amp plug | Good Sam Community

28 Replies

time2roll
Nomad
Jun 05, 2017
MetalGator wrote:
2oldman wrote:
I think you mean socket, not plug. I guess you don't get two hots - just one hot separated into two parts.
You are correct, socket not plug. The two hots would be 30 amps total between the 2, not 30amp per hot. I just want to be able to keep the coach plugged in to keep the batteries charged and to leave the fridge running.
Is outlet a NEMA L14-30? That should be two hots at 30 amps each and 240 volts between them if it is wired to code. And yes a standard generator adapter will work fine.
drsteve
Explorer
Jun 05, 2017
MetalGator wrote:
I just rented a storage garage for our new Class A motorhome. It came wired with a 30 amp plug but it's one of the twist type plugs that are typically seen on generators. I purchased a 30amp to 50amp adapter from Etrailer. I took my multi-meter to the garage yesterday to test the plug. I think it is wired correctly but I wanted to make sure before I plug in my new 100K+ motorhome!

If you are looking at the 50 amp plug, there are 3 vertical holes (one on top and two on the sides) and then one round ground plug. I believe the top hole is the neutral. Going from the top hole to one of the side holes, I get 117 volts. If I go from both the outside holes, I get 235 volts. I believe this is correct but can someone please confirm?

Thanks,
Burch

If you can measure 235 volts at your 50 amp adaptor, then the 30 amp plug is wired with two hots. No problem for your 50 amp RV, but if someone plugs a 30 amp RV into that, it's smoke time.
MetalGator
Nomad
Jun 05, 2017
2oldman wrote:
I think you mean socket, not plug. I guess you don't get two hots - just one hot separated into two parts.

You are correct, socket not plug. The two hots would be 30 amps total between the 2, not 30amp per hot. I just want to be able to keep the coach plugged in to keep the batteries charged and to leave the fridge running.
2oldman
Explorer II
Jun 05, 2017
MetalGator wrote:
I just rented a storage garage for our new Class A motorhome. It came wired with a 30 amp plug but it's one of the twist type plugs that are typically seen on generators.
I think you mean socket, not plug. I guess you don't get two hots - just one hot separated into two parts.
MetalGator
Nomad
Jun 05, 2017
sayoung wrote:
That existing twist lock plug may not be wired the same as a 30 amp rv plug. Might be wise to get that changed now to an actual rv plug . 30amp rv is 115 volts & that twist lock might be 230 so your adapter may not work. Use a voltmeter.
You are correct on the MH 50 amp.

I did use a voltmeter with the 30 amp to 50 amp adapter plugged into the twist lock 30amp plug. It measures two legs at around 117 volts. I can't change the plug since I am only renting the facility. I was a little surprised that the facility doesn't use a standard 30amp RV plug since their website says wired for 30 amp RV service. From the other responses, it sounds like it is wired correctly. My fear was plugging in and frying my brand new Class A's electrical system!

Burch
sayoung
Explorer
Jun 05, 2017
That existing twist lock plug may not be wired the same as a 30 amp rv plug. Might be wise to get that changed now to an actual rv plug . 30amp rv is 115 volts & that twist lock might be 230 so your adapter may not work. Use a voltmeter.
You are correct on the MH 50 amp.
Buddy of mine is an electrician and a few weeks back went & corrected a miswired 30 amp plug that fried a brand new rig 1st time the owner plugged in. Who ever put it in wired it like a 230v plug.. The owner said he got a good deal on wiring his new storage barn for his new rig, lol
DownTheAvenue
Explorer
Jun 05, 2017
corvettekent wrote:
Yes that is correct. So in this case you will two legs of 30 amp power.

X2
corvettekent
Explorer
Jun 05, 2017
Yes that is correct. So in this case you will two legs of 30 amp power.

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Wiring for 50amp plug

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