50A Plug on 30A power Cord

[itat]

We have a 30A Hughes Autoformer that we bought when we had our 30A TT. I made a 10 ft long 30A cord with a 30A twist lock plug so I could sit the Autoformer next to a stabilizer and lock it to the stabilizer with a cable lock.

Now that we’ve upgraded to a 50A 5er with a single AC, I still want to be able to use the 30A Autoformer in mid-summer when we’re staying on a 30A site. So I want to replace the 30A twist lock plug with a 50A twist lock plug.

So my question is for the electricians here. Since the 30A cord has a single hot line (plus a neutral and ground), can I just use a jumper wire between the 2 hot terminals on the 50A plug to feed both lines?

[Steve-W]

Yup that will work. That is exactly how a 30 A to 50 A dogbone is wired.

[nayther]

Originally Posted by Steve-W

Yup that will work. That is exactly how a 30 A to 50 A dogbone is wired.

agree, that's how my auto transfer switch is wired, two separate hot legs for 50 amp, then tie them together for 30 amp input so both buses are hot.

[itat]

Thanks for the replies. I've ordered the parts. What gauge of wire do I need for the jumper?

[Steve-W]

Since it could theoretically pull 30 amps from the source you will need 10 gauge copper. Your 10’ cord that you are modifying should also be 10 gauge minimum.

You may not be able to make a jumper fit the 50 amp plug internally. You made need to use a weatherproof box to act as a junction betwen the 4 wire 50 amp twistlock and the 3 wire from the autotransformer. This all depends upon the parts you are using.

Another option would be to use a dog bone like this and put a standard 30 amp female connector on the autotransformer cord.

[itat]

Thanks. The 10' long cord is a 25' extension cord that I cut down to 10'. I used a Christmas gift certificate to buy it so it didn't cost me anything. The Park Power/Marinco female connectors and twist lock covers on the other hand aren't cheap.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Steve-W]

You definitely got the right (good quality) connector. The way they are made you most likely will not be able to get 2 #6 into one of the hot terminals. You will probably need to use 4 conductor wire to exit the connector and then use a box to splice into the 3 conductor wire from your 10’ extension.

[itat]

Originally Posted by Steve-W

You definitely got the right (good quality) connector. The way they are made you most likely will not be able to get 2 #6 into one of the hot terminals. You will probably need to use 4 conductor wire to exit the connector and then use a box to splice into the 3 conductor wire from your 10’ extension.

Yes. I was thinking that if I use a wire that’s too heavy I won’t be able to get 2 of them into the slot where the wires go in the 50A connector. I still have the extra 15’ section I cut off the 25’ long 30A extension cord, so I’ll try using a piece of the “hot” wire from that and see if it will fit.

[nodrawers]

Why dont you just buy an adapter for about $15. Kohree 50 Amp to 30 Amp RV Plug Adapter Heavy Duty Dogbone Electrical Power Adapter with Grip Handle, Simple solution.

[itat]

Originally Posted by nodrawers

Why dont you just buy an adapter for about $15. Kohree 50 Amp to 30 Amp RV Plug Adapter Heavy Duty Dogbone Electrical Power Adapter with Grip Handle, Simple solution.

I want to avoid having to use the heavy 25’ long 50A cord when I’m using the 30A Autoformer that will sit 3-4’ from the connection on the trailer. I keep the Autoformer under a blue recycling bin for weather protection and I need a more flexible cable to be able connect to the Autoformer under the bin. I already have the 10’ long 30A cable.

The new 5er has a 50A service but it only has 1 AC, we’re used to a having 30A service and at least half the time we’re at Provincial Parks where there aren’t any 50A sites. So for now I’ll stick with the 30A Autoformer.