30 or 50 amp service connection choice

[DaveFL]

We are finding more parks are providing 50 amp service and with warmer weather it would be nice to be able to operate both a/c's with shore cord rather than running generator.

My LY 30 is presently set up for 30 amps, the schematic for the 30 amps shows it incorporates 50 amps when using the generator.

I did a search of archives but didn't see where anybody has just added an "on-off-on" to switch between generator connection and a separate 50 amp shore cord leaving the auto switches in place and not changing out the service panel. Has anybody done this? How did you prevent backfeed ing to the cord not being used?

[choctawmel]

Well, Im working on a 50 amp plug. I have an extra cord with a 30 amp plug I can pull out in my hose/electric cord compartment. I plan to make the cord/reel into a 50 amp setup some day. I just need to take all the wires loose and see if the natural isn't strapped to ground. Don't need four wires anyway, don't need anything bigger than #10 either, 'cause your not really running 50 amp in the motor home.
I put an on-off-on switch under the dinette next to the auto generator relay. One way, it's stock, the other way it goes to the extra 30 amp pig tail. Added a breaker box on each end for safety. I can run both A/C's if the park has a 30 amp and a 15-20 amp or two 30s, or a 50 amp.
mel

[gail]

Ok what is the difference. We do not use a generator and recently asked if we needed 30 or 50? can someone please explain. tx, g

[DaveFL]

Originally Posted by gail

Ok what is the difference. We do not use a generator and recently asked if we needed 30 or 50? can someone please explain. tx, g

If you need 50 amps and you plug into 30 you blow the circuit breaker, when you are drawing more than 30.
I tested my A/C's and front is 12 amps, rear is 11 running I didn't note startup which is usually more, I would guess with both starting up at once it would be 30.
AS manual gives amps of all installed items, if we were to use all we would be at the 50 amp level. Running 30 you can feel the heat in the wire and connection plug, not a good way to run, it can heat up enough to melt the connections and the next step is a fire.

[azflycaster]

Gail
Your Airstream has a 30 amp system. The plug has 3 legs. One hot, one neutral and one ground. A 50 amp connector has an additional leg on the plug (total of 4) for another hot line. The additional hot line is sometimes used for a second Air Conditioner unit. The two hot lines are also out of phase with each other and used to power 240 volt systems found in modern motor homes.

Your plug will not fit into a 50 amp connector. Just ask for 30 amp service.

A 50 amp connector:


A 30 amp connector:

[DaveFL]

Originally Posted by choctawmel

Well, Im working on a 50 amp plug. I have an extra cord with a 30 amp plug I can pull out in my hose/electric cord compartment. I plan to make the cord/reel into a 50 amp setup some day. I just need to take all the wires loose and see if the natural isn't strapped to ground. Don't need four wires anyway, don't need anything bigger than #10 either, 'cause your not really running 50 amp in the motor home.
I put an on-off-on switch under the dinette next to the auto generator relay. One way, it's stock, the other way it goes to the extra 30 amp pig tail. Added a breaker box on each end for safety. I can run both A/C's if the park has a 30 amp and a 15-20 amp or two 30s, or a 50 amp.
mel

Two A/C's, water heater, converter, microwave, reefer, TV with surround sound, toaster, coffee maker, electric frying pan, inverter for computer will be more than 50 amps on startup.
Not a good idea to eliminate the natural ground. both the 30 and 50 amp setup uses the green ground and white neutral, GFI will have problems.

[choctawmel]

I'm no engineer.

It's like the circuit breaker in your home on the electric range, it's a 30 amp 220V breaker, but that don't make it 60 amp. Same for the AS.

Right now you have a 30 amp plug. If you rewire you still only need 30 amp it's just it will be 220V. One leg of the 220V (110V) will run the electric just like it does now with the selector switch on the front A/C. The other leg of the 220V (110V) will run the rear A/C. You will need to wire a 30 amp on-off-on switch or another auto change over relay for the new circuit (for the rear A/C) so if you ever want to use the generator you flip the switch and all is back to stock, also without the switch one of the new plug prong will be hot, if you use the generator, and it may put voltage to the generator. Need to be careful about how we modify/update so as not to kill the next owner. Should draw up a diagram of any modification and keep it in the manual.

There is 3 wires into the auto changeover relay: one is power from the generator, one to the rear A/C, and one from the selector switch. Find the wire going to the rear A/C and out of the relay box and cut it. The on-off-on switch (center) goes in the wire to the rear A/C with one 'on' to the new plug, and the other 'on' to the relay box. I ran a 12-3 wire out of the front dinette, along the wall, under the refrigerator into the rear compartment above the reels. To a breaker box then down into the reel compartment.

Have seen some put a plug in the generator compartment, then they unplug the generator and plug a cord into that. I just like to be able to turn the generator on if the park power goes out without going outside and rewire/plug. Usually the power goes out when it storming.

If I figure out how to post pictures, I would.

mel

[DaveFL]

Originally Posted by choctawmel

I'm no engineer.

It's like the circuit breaker in your home on the electric range, it's a 30 amp 220V breaker, but that don't make it 60 amp. Same for the AS.

Right now you have a 30 amp plug. ....

If I figure out how to post pictures, I would.

mel

Mel,
A picture of your circuit would be nice.

I was reading the generator manual and it has a 30 and 20 amp circuit but from what I am reading, it is 120 not 220 as I originally thought. I know the present control panel is 120 so it will be much more difficult to convert to 220. Like you stated: the rear a/c circuit will have to be removed from the existing box if given 120 from a 220 input.
The 220 input has to be fed into a 220 control panel where each leg is isolated. Then one leg can be used for the original control panel and one for the rear a/c leg. Maybe this is why I saw where one member just uses a second 120v shore power cord of 20 amps to power the separated rear a/c.
Dave