How are these things wired

I think some of you folks are not reading my original post. I'm not trying to hook one of these up at a campground.

What I said was " I have access to two 30 amp RV outlets that are not wired to ground fault outlets at my HOME. I am wondering if I could use one of these to run both A/C units while at HOME.

First, they do not often work

Now how they are wired

Each 30 amp plug has 3 pins, A safety ground, A hot, and a Neutral

The 50 amp has 4 poins

The roundish pin in all cases is the safety ground,, These are all connected together.

on the 50 the TOP (opposite the round one) is the Neutral, And one of the pins on the 30 (forget which side w/o checking) and these are connected together.. See note:

The sides of the 50.. Connect to one, or the ohter (but not both) of the 30 amp HOT leads.

NOTE: because of the common neutral if you plug into a 30 amp outlet and, using the needed adapter into a 20 amp outlet.. POP goes the GFCI, if it does not, it is not working properly Yes I can design one that won't do this, but it is both HEAVY and Expensive

I don't think I've ever encountered, in a campground with 30 amp service only, a box with two 30 amp outlets on opposite phases of a 240 V distribution. If the CG is wired for both phaes to each box, it is going to have a 50 amp outlet in the box.

I think of this as an adapter for an unlikely situation.

Sounds simple enough. If I go this route, I think I will do what Doug suggested and just wire my own. That way I'll know it's done correctly.

It might be just as easy to pull a new 6 AWG copper wire and go ahead and wire it for 50 amp to start with. It's not a very long run; maybe 30 foot max.

The cord in the assembly is only #10.

enblethen wrote:
The outlets must be on opposite phases of the power service. If on the same phase, you have the potential of burning up the neutral.
some of these adapters have a warning label indicating this.

Neutral in the RV is #6 and fine at 60 amps.

Doubt the adapter is all #6 so yes with a bad connection the adapter may burn up.

The outlets must be on opposite phases of the power service. If on the same phase, you have the potential of burning up the neutral.
some of these adapters have a warning label indicating this.

Just remember, IF one of the 30 amp receptacles has reverse polarity(the white and black are reversed due to incompetent install), you will supply a "220" type hit to your RV. When using these adapters it is best to make an adapter to verify polarity with a standard polarity checker. I have fixed a few RV's over the years from this happening. This is more critical when you do not have a extra 30 but adapt down to a standard 15 amp receptacle as they are easier to reverse the polarity. Doug

Tinstar wrote:
Do they just run the 30 amp hot to one side, the other 30 amp hot to the other side then combine the two neutral wire and then combine the two ground wires.

That is exactly correct.

KD4UPL wrote:
You have a great understanding of how they work.
I would make sure your 2 30 A outlets are on opposite legs. If you measure between their hots you should see 240v. Otherwise, you could potential overload the neutral wire in your RV.

Electrically this is absolutely correct. If you turned on enough load, you could load the neutral to 60 amps vs a maximum of 50 amps for "real" 50 amp service. This is because with 50 amp service the neutral only carries the DIFFERENCE between the draw on L1 and L2.

Reality-- it would be very rare in a CG pedestal with only 30 amp service for the two 30 amp outlets to be on "opposing" hot legs. If they pulled the extra wire, they very likely would have installed a 50 amp outlet!

So, yes, some attention needs to be paid to total amp draw. Remember 50 amp is TWO 50 amp hots, so 100 amps total. This 30/30 to 50 offers 60, a single 30 offers 30. RV math.