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Old 07-29-2012, 04:06 PM   #1
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50 amp to 30 amp adapter

I am thinking about getting a 30 amp outlet put in my home for my AS. But I saw at Walmart today a 50-30amp cord/converter and thought I could use that to plug in where my dryer is. But does it power down the power, is it safe to plug a 30 into a 50 with this converter, will I blow up my camper if I plug in this way?
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Old 07-29-2012, 04:12 PM   #2
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That is what I do at home and when I am at a campground that only has 50 amp.
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Old 07-29-2012, 04:20 PM   #3
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A 50 amp supply will supply up to 50 amps. If your trailer draws less it is just supplied with what it needs.

An electric dryer often uses 220 volts. Make sure you are only getting 110 into the trailer. I am not sure if there is a difference with the plug.
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Old 07-29-2012, 04:24 PM   #4
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Residential electrical service provides 2 110v legs to the breaker box. A 110v circuit is a connection between one or the other hot leg and neutral. A 220v circuit is a connection between the 2 hot legs. The 50 amp service at the park's power pole is a 220v outlet like your dryer outlet. RVs are wired to use the 2 100v legs separately. The 50 to 30a pigtail simply drops one of the legs. So it would work to use the pigtail plugged into a dryer outlet, but to be sure, I would test the outlet of the pigtail with a meter first.

A 50a plug has 4 pins: 110 phase 1, 110v phase 2, neutral, and ground. A 30a plug had 3 pins: 110v phase 1, neutral and ground.

As previously mentioned, the 50a post uses 50a breakers, but your main breaker in the trailer limits the current draw to 30a max on your shore line cord.
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Old 07-29-2012, 05:10 PM   #5
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I wouldn't do it because the trailer is designed for 30 amps, to be limited to 30 amps where you plug it in. The cord, service entrance plug, wiring to the trailer breaker panel, and on newer models an automatic power transfer switch are not designed to handle 50 amps.

Excessive power draw could be experienced with a short ahead of the breaker panel, or power spike when drawing a heavy load and switching on, say, the a/c. The breakers/fuses do not shut off instantly, but momentarily allow high current draw to activate the protection.

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Old 07-29-2012, 05:18 PM   #6
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I wouldn't do it because the trailer is designed for 30 amps, to be limited to 30 amps where you plug it in. The cord, service entrance plug, wiring to the trailer breaker panel, and on newer models an automatic power transfer switch are not designed to handle 50 amps.

Excessive power draw could be experienced with a short ahead of the breaker panel, or power spike when drawing a heavy load and switching on, say, the a/c. The breakers/fuses do not shut off instantly, but momentarily allow high current draw to activate the protection.

doug k
Re-read (or read for the first time) Post #4. With a proper adapter, you will split off a single 120VAC leg from the double leg (2 X 120VAC hot legs) 50 amp 240VAC dryer outlet with NO DAMAGE to your 30 amp trailer wiring, transfer switch or anything else. This is done every day in campgrounds that are only wired for 50 amps when older/smaller motor coaches and trailers with only 30 amp service plug in. They all need 50 amp to 30 amp adapters that work as stated above. And BTW, a short will still trip the breaker!

Have no fear, but do buy a quality 50 amp to 30 amp converter plug.
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Old 07-29-2012, 07:01 PM   #7
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Originally Posted by dkottum View Post
I wouldn't do it because the trailer is designed for 30 amps, to be limited to 30 amps where you plug it in. The cord, service entrance plug, wiring to the trailer breaker panel, and on newer models an automatic power transfer switch are not designed to handle 50 amps.

Excessive power draw could be experienced with a short ahead of the breaker panel, or power spike when drawing a heavy load and switching on, say, the a/c. The breakers/fuses do not shut off instantly, but momentarily allow high current draw to activate the protection.
If this were true, every appliance we plug in at home would have to add up exactly to match the rating of the circuit breaker on that circuit.

He'll just be drawing less than the circuit can supply. No problem.
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Old 07-29-2012, 07:23 PM   #8
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is your dryer...

really on a 4 wire 50amp 240VAC circuit? Most dryers are on 30amp 240VAC circuits. The NEMA plug/receptacle's for the two different circuits are different. An RV park 50amp to 30amp adapter is to adapt a 4 wire 50amp 240VAC female receptacle to a 3 wire 30amp 120VAC female receptacle. It is relatively simple to make a 4 wire 30amp 240VAC to 3 wire 30 amp 120VAC adapter, just got to get the right plugs/receptacles and a chunk of wire. Neutral to Neutral, Grounding conductor to grounding conductor; ONLY one hot lead to the black hot of the 120V female receptacle; there is NO connection to the other hot lead. The commercially available adapters are so much better than one you'd build however. I have never seen a commercially available 30a 4 wire 240VAC to 3 wire 30m 120VAC adapter. As soon as I submit this, someone will have a source-I just haven't seen them.
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Old 07-29-2012, 10:55 PM   #9
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My point about adapting to a 50 amp receptacle was poorly expressed on my part.

More simply (?), my power cable, internal wiring to the breaker panel, and automatic transfer switch are designed for 30 amps. If I adapt to a 50 amp supply and there is a short or power surge at the breaker panel, those items are not protected by the trailer's 30 amp breaker. Those items before the trailer's breaker panel will see 50 amps (and probably more) before shut down. That could fry the power cable, internal wiring, or automatic transfer switch because they are not designed for 50 amp loads.

The fact that is done all the time does not remove the risk. Others can do as they wish, I just said I wouldn't.

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Old 07-30-2012, 07:16 AM   #10
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When I built our house 12 years ago the code required a 4 wire 30 amp receptacle for the dryer. It now requires the neutral and ground to be separated at the dryer. Unlike the old 3 wire receptacle where the neutral and ground were tied together.
Most of the older rigs that I'm aware of don't have the auto transfer switches etc. And those that do have a 30 amp main at the panel inside the trailer will have the 30 amp protection down stream from the main in the trailer.
Whether you have a 50 or 30 amp service and have a short between the service panel and the main in the trailer. ie in the shore power cable is irrelevant since the damage would be severe in either case.
No matter which way you decide to go. I think it is always smart to check the voltage at the point where you plug the shore power cord. Whether you use an adaptor or not. Also that your rig is wired correctly, ie ground etc.
I must say I've never been in a campground that has only 50 amp service available. But, I haven't been everywhere.
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Old 07-30-2012, 08:35 AM   #11
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I carry a 50 to 30 amp adapter dog bone whenever I travel to unknown area. I got stuck in a campground five years ago where they only had 50 amp sites still available at 7:00PM and I had to buy one for $20.
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Old 07-30-2012, 02:30 PM   #12
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So what's the verdict? If there is a 4 plug dryer outlet and my multimeter says 120 on each side I'm safe to use my dogbone adaptor? The dogbone eliminates the extra 120 side? Obviously I'm not an electrician but smart enough to consult one when I'm in over my head - or ask the forums.
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Old 07-30-2012, 03:24 PM   #13
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So what's the verdict? If there is a 4 plug dryer outlet and my multimeter says 120 on each side I'm safe to use my dogbone adaptor? The dogbone eliminates the extra 120 side? Obviously I'm not an electrician but smart enough to consult one when I'm in over my head - or ask the forums.
My garage has the same exact 50amp receptacle and I just used it with the 50A to 30A adapter to test the A/C in the drive way with no problems at all. As stated each leg is 110 nor does your meter lie.
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Old 07-30-2012, 06:51 PM   #14
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Howard, were you using the 50 amp to 30 amp adapter when your auto transfer switch burned out recently?

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