shadoow
North Texas
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Joined: 09/25/2007
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I've heard of others doing this, but need some help on getting things sorted out.
I've got a 5th wheel trailer with 50 amp service and 2 AC's. I'd like to wire the front AC so it can be independently powered from a 20 amp outlet at the power pedestal if needed. That way we could camp at a site with 30 amp service and i could power the front AC from the
always-present 20 amp service. I'm trying to make this power lineup switchable so i can leave the front AC powered from it's normal source at the trailer breaker panel or switch it to a separate power line that would be plugged into the pedestal 20 amp service.
Here's what I've done so far. I disconnected the power cable for the front AC from the breaker panel in the trailer and connected it to a new junction box. I then ran a power cable from the breaker in the breaker panel for the front AC to the same junction box. I figured i can use the breaker in the panel to power up that cable when i want the front AC to be powered from the trailer as it normally is. Finally, I installed a power cable from the junction box to a new outlet on the outside of the trailer. I'd then be able to connect a power cord from this new outlet to the pedestal 20 amp service. I ran the hot lead for this power cable thru a switch so I could enable or disable the outlet as needed.
So, all 3 cables come together in the junction box i mentioned earlier. I've 3 terminal strips in the box with each providing a common connection for a different wire type, so there's a common terminal strip for the hot leads, a separate one for the neutral leads and a 3rd one for the ground leads.
The thought in all this was if i wanted to have the front AC powered directly from the pedestal 20 amp service, I'd first open the breaker in the trailer (breaker panel) for the front AC. Then, I 'd close the switch in the power cable going to my new outlet on the outside of the trailer. This would enable my outlet so when i connect a power cord to it from the pedestal i should have power to the front AC.
I tested this setup at 2 campsites and it didn't work as expected. I did everything to line up the power cables as i described above, but whenever i plugged the power cord into the pedestal 20 amp service the breaker overloads would trip on the pedestal. I tried it again, this time with the switch for the power cord open and the overloads for the pedestal breakers would still trip.
I can close the breaker for the front AC that's in the trailer (breaker panel) and the front AC works fine. I've re-checked my wiring and all seems to be good. When i take voltage measurements at the new outlet i get 120V from hot to neutral and from hot to ground. I get 0.4 V from neutral to ground which is similar to what i get when i test an outlet in the RV.
Any ideas on what i'm doing wrong with this setup that's causing the pedestal breaker overload to trip??
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teddyu
Enfield, Ct
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My guess is that the 20A receptacle at the pedestal is powered from the 30A circuit breaker for the 30A plug. Probably wired this way to prevent what you are trying to do. JM2C...
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dupreet
High Point, NC
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I think your best bet would be to install a small manual transfer switch instead of the junction box, strips, and switch. This way, the hot, neutral, and ground would switch from one power source to the other, leaving no chances for things to get switched wrong, or any imbalances on the neutrals to occur.
A quick search online came up with this one for less than $100
Link
Todd
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KD4UPL
Swoope, VA
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First of all, I think you're going to a lot of unnecessary trouble. You can get an adapter that allows your trailer's 50 amp plug to be supplied by a campground 30 amp and 20 amp. This, if I understand correctly, is what you are trying to be able to do. This gets you 50 amps at 120v, half what a true 50 amp connection gets you.
You say that you are tripping the 20 amp overloads on the pedestal. I'm guessing you mean the little button pops out on the GFCI receptacle. Most campground 20 amps are GFCIs. If this is what's happening it's because you still have all the neutral wires in your junction box hooked together. This causes 2 paths for the neutrals and makes the GFCI trip. The way to fix it is to use a double pole switch between your junction box and outside outlet. This will allow you to disconnect both the hot and the neutral.
An other problem I see is that you are feeding this new circuit from an outlet on the outside of the trailer. I hope you mean and inlet. If it is truly an outlet then I must assume you have made a cord with 2 male ends. This is extremely dangerous as it can result in exposed prongs being electrically live. There are box mountable 20 amp power inlets available. One of these would be a much better choice.
If it were me, I would remove all the extra wiring you put in and purchase the adapter.
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smkettner
Southern California
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You really need to switch both the neutral and hot. Especially if the 20a is GFI. BTW does the 20a breaker trip or the GFI?
I agree that instead of the J-box with light switch, get a 30 amp automatic transfer switch.
http://www.amazon.com/Progressive-Dynami........10010V-Automatic-Connector/dp/B0039T0518
Not certain I would trust the 15a switch linked above on a 20a circuit.
I don't think the 30/20-50 adapter will work on GFI outlets.
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dupreet
High Point, NC
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Or a simply route - at the junction box you put in, have two standard Edison duplex outlets, one fed from the breaker and one fed from your new 20a feed into the camper. Put a plug on the line going to the AC and just plug into one or the other...no chance of any issues!!
Todd
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dupreet
High Point, NC
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In reguards to the 30a+20a adapter, I believe they trip the GFCI on the pedestal too, due to the bonded neutrals you end up with. The discrete outlets I suggested avoid this issue.
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SolidAxleDurango
OK, USA
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Transfer switches transfer only the hot. Not neutral or ground.
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smkettner
Southern California
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30 amp ATS wire diagram
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nalcon
SE Texas
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dupreet wrote:Or a simply route - at the junction box you put in, have two standard Edison duplex outlets, one fed from the breaker and one fed from your new 20a feed into the camper. Put a plug on the line going to the AC and just plug into one or the other...no chance of any issues!!
Todd
I did the same basic thing on my 30a Class A. I found the wire from my rear AC to shore power and generator. Snipped it and installed a male and female receptacle, female to the shore power side. When plugged together my rear AC runs off shore power. Unplug and connect to an extension cord to pedestal and the AC runs off 20a.
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