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

MetalGator
Nomad
Jun 09, 2017
JoeH wrote:
MetalGator wrote:
Playtime II wrote:
Looks like my marina receptacle. If they store mostly boats then that would answer some of the WTHs.

They advertise RV and Boat storage so maybe that is why it has this receptacle.

where is this storage facility--- if it's near me, I may be interested in a spot

In downtown Palmetto right off Business 41. They are brand new units. The place just opened April 1st. There are 26 units and half of them are booked so far.

Here is a link to the website.

Jumbo Storage
JoeH
Explorer III
Jun 09, 2017
MetalGator wrote:
Playtime II wrote:
Looks like my marina receptacle. If they store mostly boats then that would answer some of the WTHs.

They advertise RV and Boat storage so maybe that is why it has this receptacle.

where is this storage facility--- if it's near me, I may be interested in a spot
MetalGator
Nomad
Jun 08, 2017
Playtime II wrote:
Looks like my marina receptacle. If they store mostly boats then that would answer some of the WTHs.

They advertise RV and Boat storage so maybe that is why it has this receptacle.
Playtime_II
Explorer
Jun 08, 2017
Looks like my marina receptacle. If they store mostly boats then that would answer some of the WTHs.
MetalGator
Nomad
Jun 08, 2017
wnjj wrote:
Thanks for the pictures; that clears things up. 4-wire is what you have and what you want.

You have a total of 60A available (30A per leg) at 120V.

You must have one of these breakers:

Yes, that is the breaker. They advertise that their garages have a 30 amp RV plug. I was incorrect in saying the add said 120v. They just say 30 amp RV plug. I guess this will accommodate both 30 amp and 50 amp RVs assuming they have the correct adapter. All I will be powering is a dehumidifier during the summer months and the fridge a day or two before we take a trip.

Burch
westend
Explorer
Jun 08, 2017
Yes, that receptacle is a unique situation for an RV. Whoever called for the twist-lock 240V receptacle to be installed did not know typical RV wiring or was looking for a solution for both 30 amp RV's and 50 amp RV's. If a 30 amp 120V RV was to connect to that receptacle, they would need an adaptor where only one leg of the power from the twist-lock was connected through the adaptor.
wnjj
Explorer II
Jun 08, 2017
Thanks for the pictures; that clears things up. 4-wire is what you have and what you want.

You have a total of 60A available (30A per leg) at 120V.

You must have one of these breakers:
Chris_Bryant
Explorer II
Jun 07, 2017
I'm confused :) That is what I thought you had at first. That's fine- 4 wire to 4 wire, 30 amp 240 vac to 50 amp 240 vac.
MetalGator
Nomad
Jun 07, 2017
Here are a couple of pictures I took. The receptacle says 120/240 volt
MetalGator
Nomad
Jun 07, 2017
I just took my Progressive EMS model EMS-PT50c and drove to the storage facility. I hooked it into the adapter and it gave an E0 code (normal condition) and said L1 was 114 volts and L2 was 113 volts. I took my multi-meter and it matched the voltage the EMS said. I did look at the 30 amp breaker and it does seem to take up two slots in the breaker box but only one slot has the breaker switch. On my 220 volt breakers at my house they take up two slots but have two switches that are connected with a metal clip that throws both switches when you turn it on and off.

Long story short, if the EMS unit is happy I guess I am OK

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Wiring for 50amp plug

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