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Ron_Nielson's avatar
Ron_Nielson
Explorer
Jul 13, 2015

20 Amp Circuit to Support 2nd A/C Unit

I'm pretty sure one of you have already done this the easiest way, so no need for me to reinvent the wheel, right?

My trailer is a 30 amp system, so I believe the easiest/cheapest method is to add another 20 amp circuit specifically to run the 2nd a/c unit I plan to add.

I considered just adding a 20 amp extension cord plugged directly into park power, but I believe most parks will have the 30 amp circuit and the 20 amp circuit fed from the same 30 amp source and that may not be enough to run 2 units (and other electrical appliances) at the same time. Of course, at the time you are running both a/c units it is 105 * and it's going to be that way for hours, so is everyone else around you and the available volts/amps may not be up to standards, so I feel it is important to have a setup that is at least somewhat tolerant of the situation. Some have told me that the shore power 30 amp circuit and 20 amp circuit are fed from different sources. True? What I have been able to read about is that modern 50-30-20 amp service has one source for the 50 amp service, another source feeding the 30 and 20 am services.

Option #1
Starting from the park's power to the a/c unit, perhaps use a 50 amp to double 30 amp dogbone from the park power pedestal, 30 amp extension cord to the trailer thru-wall connector (has to be added), add breaker box with 20 amp breaker, then hardwire 20 amp circuit to the a/c unit.

Option #2
Change out my 30 amp cord to a 50 amp cord. Use one leg of the service to tie into the existing 30 amp power center; use the other leg adding a separate breaker box with 20 amp breaker to power the 2nd a/c unit. If I happen to be at a park with only 30 amp service,I could use a 50 to 30 adapter. Just have to be sure that when wiring the 50 amp cord to power center, I use the side that will be powered thru the 30 amp adapter. (Do all adapters do this the same way?)

A good thing about option #1 is 1) I have 50 amp service when I need to run my 2nd a/c and 2)when I don't need both a/c units, I just plug my existing 30 amp cord into the 30 amp service. A down side to this is that the 50 to 30 dogbone is not cheap ($100+)compared to other adapters I have purchased and I have to add the thru-wall connecter. For option #2, changing out the cord to 50 amp has it's costs (50 amp power cord is $125+) and handling the 50 amp cord year round has it's downsides, big, bulky, doesn't want to bend in cold weather, takes more room to store (I will probably have to make a different storage area for it), etc.

So who has done this or something similar and would offer suggestions or improvements or alternatives?

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