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Old 07-29-2012, 03:06 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, 03:12 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, 03:20 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, 03:24 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, 04:10 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, 04:18 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, 06:01 PM   #7
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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.
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, 06:23 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, 09:55 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, 06:16 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, 07:35 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, 01:30 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, 02:24 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, 05:51 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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Old 07-30-2012, 06:26 PM   #15
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Electric ranges are 50 amp and 240 volts. Dryers are 30 amps and 240 v.

Regardless of that, once you eliminate one of the 2 hot wires of a 240 v. circuit, you would have a 120 v. circuit and half the amps too (I think, Lew will correct me). Depending on the rating of the receptacle, I would think that would be either 25 amps or 15 amps. 15 is too low for the A/C.

I don't think a dog bone for 50 amp to 30 amp has the right lugs for a 30 amp dryer receptacle. Every receptacle and plug has a specific pattern for each voltage and amperage so you don't plug the wrong thing into the wrong receptacle.

If you decide this is brain damage material, hire an electrician, but make sure the electrician knows what a 120 v., 30 amp RV plug looks like. They are hard to find sometimes and some electricians, even ones with licenses, don't know what they are or what they look like.

Three photos below: the one on the left is a 30 amp, 240 v. dryer receptacle, the one on the right is an RV 30 amp., 120 v. receptacle and the one on the bottom is a 50 amp, 240 v. range rec.

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Old 07-30-2012, 08:59 PM   #16
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A 50 amp stove receptacle has 50 amp capacity on each of the 120 volt legs. Thus the requirement for #6 copper wire to feed it. A 30 amp dryer receptacle has 30 amp capacity on each 120 volt leg. Thus the requirement of at least #10 wire.
If you look at the double pole circuit breaker in the panel providing power to either of the above. You will note that whether it is 30 or 50 amps that number is on each of the circuit breaker handles. Not half as mentioned above.
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Old 07-30-2012, 09:07 PM   #17
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In the photos that Crawford Gene posted. They show up 3 abreast on my iPod. The one in the center is the 30 amp 120 volt receptacle designed for travel trailers.
Zoom in on it and it is clearly marked "For Travel Trailer Use Only".
It also is clearly marked "120 volts"
If you have an electrician install this. Make certain he/she understands that it is 120 volt; not 240 volt.
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Old 07-30-2012, 11:53 PM   #18
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Howard, were you using the 50 amp to 30 amp adapter when your auto transfer switch burned out recently?

doug k
Tiger Run just put in new service at some of the older trailer spots which we had one. I started out on the 30A when it burned the contact the first time. I then put the adapter into the 50A service and sill no power. It was not until I read the responses to my post for help that I realized what was going on. So I put 20A power into the generator plug upfront to force the relay to change states upon which the power came back on. Then I changed back to the shore power plug which was still with the adapter in place. The current being fed to the trailer was not the issue at all put the current being drawn by the trailer through the ATS.

As I explained to Dan Snider at the factory: “As discussed my belief is that with electric refrigerator, electric hot water, A/C on, and lights on that when the AC compressor cycles on a few times the current spike overloads the relay contact surface and causes it to burn or otherwise carbonize interrupting the current flow. When this happens the trailer 110 just shuts off and will not restart. There are no breakers tripped at the trailer or the shore box. You cannot clear it until you plug into the generator connection at the front of the trailer causing the relay to change over (break the burned normally closed contact). Then you can go back to the shore plug and it will work again for a little while and fail.”

You can cause the ATS to fail at will without blowing a single breaker by following the above setup. With current being drawn by the refrigerator, hot water, converter and the A/C compressor cycling on and off it will burn just as shown in my picture of the relay contacts in other threads. The Parallax ATS switch is just a cheap China made relay not a heavier duty contactor found in all other ATS switches.

I left the old Parallax ATS at the dealer this morning and asked for a replacement. I am happy to pass it along to anyone wanting a spare if the factory provides it, but they already know I have upgraded it so I would guess not!
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Old 07-31-2012, 10:49 AM   #19
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A 50 amp stove receptacle has 50 amp capacity on each of the 120 volt legs. Thus the requirement for #6 copper wire to feed it. A 30 amp dryer receptacle has 30 amp capacity on each 120 volt leg. Thus the requirement of at least #10 wire.
If you look at the double pole circuit breaker in the panel providing power to either of the above. You will note that whether it is 30 or 50 amps that number is on each of the circuit breaker handles. Not half as mentioned above.
TG, thanks for the correction. It makes sense now that you explain it.

The automatic transfer switch is a new thing. I am unsure what it does and why it wasn't needed on earlier models, or what was used in its place.

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Old 07-31-2012, 11:56 AM   #20
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Gene, the auto transfer switch allows you to plug a generator (or campground power) into the front side of your trailer, as well as rear roadside. There is an additional receptacle on the front of the trailer.

Handy for those with big generators in the back of pickups. The ats automatically finds your chosen power source, but prevents two power sources at once.

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