By the way, here are the parts and stock numbers of everything I purchased from Lowes:

246564 30a 125v trailer plug $8.99
83896 15a 125v 3 wire angle plug $9.97
246874 50a 125/250v 4 wire surface mount range plug 10.87
45362 1" connector $1.37
56502 10/3 wire 2.0' $2.96
70073 12/3 wire 2.0' $2.06

...and I wired it as hitchhiker states above. Thanks Hitchhiker!!

Looks like that's about half the price of the one from Camping World.

I built 2 of these, one for me, one for a friend. He just called me from a campground and says it pops a main breaker in another panel nearby. He said he can plug in the 30a side, but when he plugs in the 20a side, it pops a 60a breaker in another panel nearby. He says this other panel is full of 60a breakers that feed each individual panel at each site. Any ideas????

Sounds like maybe one of the wires is in the wrong place.

Since I frequently run across Ground Fault breakers I decided to put my rear air on it's own circuit.

I located the rear ac's romex at my power center and disconnected it. I then ran romex from that breaker to a 20 amp female recepticle in my bay. I marked it 50 amp. The romex from the ac, I installed a 20 amp male plug. So, if the ac was plugged into the above female recip, it would be like the factory setup.

I then made a 35 foot, 20 amp extension cord, and mounted it's recip in the bay as well. I marked it 30amp.

Now, if I'm at a park without 50 amp, I plug into 30 amps with my shore cord and adapter. I then plug my 20 amp into a 15/20 amp recip at the pedistal. I plug the AC Plug into the appropriate plug in the bay.

This allows the ground circuits to be totally separate so you can still hook up to a GF without issues.

The cost is very close to doing the cheater box, but the labor may take an hour or so more depending on your setup.

2 20 amp female recip boxes.
2 20 amp male plugs
xx' feet of 12ga wire for your 2nd shore cable.

My setup is complicated by the fact that I have a Pulse Air installed to alternate the two A/C's on a 7/5 minute basis.

I located the rear A/C cord from the Pulse Air, which was in the cabinet above the fridge, and cut it. I then installed two new Romex lines from the cut ends, inside the wall, and through the AC power/converter area to an available space next to the gray water tank. I put a plug on the line to the rear AC and a socket on the line to the generator 20 amp breaker. I also put in a socket on the line back to the Pulse Air. I currently use a heavy extension cord from that area as a second shore connection. Now I can plug the rear A/C into the generator when we're on the road or into the extension cord when we are in camp. I can also plug it into the Pulse Air when at home to alternate the A/C's.

I have an ATS which I plan to install in place of manually moving the plug from generator line to the shore cable. I will wire the ATS so I still have the option to manually plug the rear A/C into the Pulse Air for home use. The ATS will select the gen or shore source when traveling/camping.

(For those familiar with Pulse Air, I should be able to run both A/C's from the generator, but that feature hasn't worked in a couple of years, and Pulse Air seems to be out of business.) If I choose to eliminate the alternating feature, I can reinstall an original front/rear/both switch in place of the Pulse Air and only need to wire in the ATS to select the source of power to the rear unit. Either way I only need a 20 Amp source for the rear unit and get cooling throughout the motorhome...A REAL lifesaver during the recent 2008 iRV2 National Rally.

If you use a 'cheater' box, either store bought or homemade, a good investment is a 110/220v test light. Plug the cheater into its two outlets, and then stick the leads into the 2 hot pins (parallel blades). If you read 220v, then you are probably in good shape (except for GFCI, of course). If you read 0v, then the 2 hots are NOT out of phase and you should NOT use the box because of the chances of overloading the common return.

By the way, also good to put one lead into the common return pin (opposite the ground pin) and test to each hot to ensure 110v.

Also a good idea to use the test light on 50 amp service. I found a park where they had put the breakers in wrong and both of the hots were in phase (powered by the same side). I have PMS (the electrical kind) which caught it, but if I didn't have the PMS, it might of been exciting.