I have decided to go ahead and up-date my Budget Barth to 50 AMP service so I can run two A/C's at the same time. One A/C in the southern heat was just not working. I have a general idea what to do but would like see what you guys think of my idea and give me some advice.
I understand that the 50 Amp service is basically two 25 Amp (or one 30A and one 20A?) lines with a common neutral. What I was going to do was leave the original 30A box like it is and just add another box for the other leg. In this box I would wire the second A/C and run some new circuits to the front and rear of the RV. Is this safe or do I need to keep all the breakers and wiring in the same box?
I am also going to install a generator change over switch, I would like a manual switch but I am having a hard time finding one. The Auto switches would be nice but is just seems like another thing to fail. My generator is only 3.5K and will not run both A/C's. I will wire the gen to power both legs so I can chose one A/C or the other when on the generator. I will just have to be careful to not overload the gen but this would convenient.
Do the 50A to 30A plug adapters just combine the X & Y terminals together or do they drop one?

Any advise would be appreciated.

Neil.

50 amp service is 50 amp on each leg and the two hots are out of phase so that between the hots you have 240vac


|----240----|
|-----|-----|
110 N 110

Two boxes works for me and you can tie the 110s together at the adapter and feed 110 to the entire system or if you have a campground with 50amp service you can use that also.

To explain further you need a new power cord with 4 wires. Black, Red, White and Green. Black and red are the two hots, white neutral and green ground. This you terminate with a 50 amp plug. Next get a 30-50 amp dog bone. The dog bone will have the two hots tied together. This allows you to feed same phase 110vac to both legs. Next put a 30 amp outlet from the generator to the power cord compartment. Now when you are on the road you plug the dog bone into the generator outlet.

Also you can run two ACs off of 3.5kw if your ACs are 1500 watt or less. You just have to turn off all the other stuff and change the refegerator to gas. If you have one of the new TVs you may still be able to watch tv.

When I converted a bus I ran the wiring for the read AC into the bay and then back to the breaker box. I had plug in the bay that I could unplug and then plug into an extension cord and run the rear AC from the 15amp outlet.

quote:

The dog bone will have the two hots tied together. This allows you to feed same phase 110vac to both legs.

Both hots tied together is a dead short. The 30A adaptor runs off one leg of the 50A socket.

I haven't seen a 50 amp to 30 amp plug or adapter. You would have to use only 1 leg of the 50 amp service, but most if not all RV parks if they have 50 amp service outlet, also have a 30 amp service outlet next to it.

The 30 amp to 50 amp adapter (dogbone) does tie both of the RV 50 amp legs tied together.

quote:

The 30 amp to 50 amp adapter (dogbone) does tie both of the RV 50 amp legs tied together.

I've never checked if 220 is available between the two legs (hot wires) but if it is it would be a dead short to connect them.... If both legs (hot wires) are 110 to ground AND 110 between them. then all is fine in what you want to do....

It IS 220VAC across both hot legs; it's the usual residential/light commercial wiring.

Some newer coaches even use 220VAC for clothes dryers.

Seems to be a little confusion here. If you have a 50amp service on your coach you do have 220volt, two hots. Not good to combine them if fed from a 50amp 220volt outlet. If you are at a site with 30amp available you need to adapt your 50amp 220volt coach to use the 30amp 120volt. This is where the 30amp (MALE) to 50amp (FEMALE) adapter is used. This adapter does tie the two hots together on the 50amp coach side. It wouldn't last long if it were the other way around

I'll add to the confusion here. My big cord has a 50 male plug and the plate on the little door says 50a. I never used the 50, always using the adapter to 30a at parks, and another adapter to a regular plug at home. [I don't run the AC at home]. At Nicks last weekend, I tried to plug into Nicks 50a service and got a big spark when trying to plug in without shutting off the circuit first. We shut off the circuit, plugged in, and proceded to blow the breaker in the barn and in the coach. After trying a couple times we plugged Rusty in to the 50a using his 30-50 adapter, and plugged me into the 30a using my 50-30 adapter and all was fine for the duration. Nick uses the 50a all the time, and Rusty had no problem convertd to 30a to the coach, but why wouldn't my coach accept the 50a, when that's supposedly what it's supposed to run off?

Danny, there is only one reason, it is wired incorrectly. Could have been a PO that did it or??? Check the legs with a VOM with the coach disconnected and see what you have. I also would bet the 110 has an incorrect ground on one side.

quote:

Could have been a PO that did it or???

What's a PO?

quote:

Originally posted by noble97monarch:

quote:

Could have been a PO that did it or???

What's a PO?

Previous Owner

Danny, It sounds like someone has jumpered your coach wiring to only accept 120volt feed.

Just to clarify, I was talking about an adapter to plug a amp 50 amp plug in a 30 amp socket. I assume it just connects the one hot leg to two hot legs of the 50 amp plug. This is how I will wire the generator change over switch. The problem I am having now is finding the correct box.

A 50 amp service is not 220v! It is two standard 30 amp hot leads with a common neutral and a mechanical ground. The shore side will have two separate 30 amp breakers leading to the 4 wire cord receptacle. These are easy finds at any home center. Though you can read 220 across the hot prongs each leg will read 120 from neutral. I have never taken the dogbone apart to see if the two hot leads are tied together because it is unnecessary. When you connect to the single 30 amp outlet you will get one 30 amp circuit. If you load the dogbone with normal ac and other appliances you will burn it up and if not you will certainly find it very hot to the touch. Many owners regularly have to replace them. If you want to use 30 amp regularly it is best to install a sub panel in the coach that feeds the essential loads and use a transfer switch to tie the two together when a 50 amp feed is available or your generator is running. On my coach the transfer switch detects the source of power and will automatically choose the most efficient one. First it checks for shore power and if connected it switches to it. If not connected it checks the generator and if running it connects that, and finally if neither is running and you have an inverter it will connect it. IOTA makes switches that will do what you want and their tech people will advise you on the wiring and safety issues.

quote:

Though you can read 220 across the hot prongs each leg will read 120 from neutral.

That is called a "difference in potential" which is the defination of voltage.... If they each read 110 to ground BUT 220 between them then there is a difference in potential in those two conductors which equals BOOM!!!! I didnt check the voltages in Milford but I DID notice that it was a SINGLE 220 50amp breaker which consits of two 110 50amp breakers connected mechanically at the handle so you cant shut off either one without the other... That is a typical 220 single phase breaker but will still read 220 volts across the two terminals... Unless the parks are wired in a manner I've never seen (unlikely) then the 50 amp plug is 220 volts NOT 110....