220V/30 Amp vs 220V/50 Amp

[DrDaveMA]

After reading the above responses, IMHO the best thing the OP can do is contact a licensed electrician. Your coach is to expensive to trust it to opinions posted here.

[twinboat]

The big deal about using old style 30 amp 220 volt dryer outlets, was when they used them ON 30 AMP 120 volt RVs. Relics of the past.

This outlet has the 4 wires. It is wired the same as a 50 amp outlet, just short 20 amps per leg.

The outlet in question has L1, L2, neutral, and ground. The 50 amp RV cord had the same. Just match them up.

All that don't undestand this, go look at your RVs 50 amp plug. Its marked 50 amp, 125/250 volt. Zoom into post #10 and read it.

[BigBadDad]

One thing to think about. In all this there has not been a single mention / question that I noticed regarding the length of the cord you are planning (except 50ft. would be nice) plus the existing house run, nor the load you expect it to handle. That alone tells me you should just let a qualified electrician handle the work if you can find one that will do it.

[Isaac-1]

My big concern is this shop outlet may not be wired like a standard 4 prong dryer outlet, it is common to find people using off the shelf dryer or stove outlets and wiring them for 240V only for arc welders, or for 3 phase electrical equipment in home shops instead of using the correct outlet / plug for such applications (the correct shaped less common outlet will likely cost more and be harder to find). Therefore unless an actual modern electronic display dryer is plugged into that outlet my first step would be to put a meter on it an confirm the sockets have the expected 120V L-N, 240V L-L and ground is ground.

If it does all you need is a $10 4 or so foot long dryer cord and a surface mount RV/stove style 50 amp outlet box and wire them together. Total cost should be about $25.

[Kiawah]

This is not a big deal to make, if you know what you are doing. I have made a similar one myself. It's just a short dongle you are making, can be 1 or 2 feet long.

I built an additional detached garage/shop, and when I built it 20 years ago I added a 240v 30A outlet about 2 feet from the breaker box. The purpose was so I could hook up the output of a generator to it, in the event of a power outage. I flip the mains in the house, plug in the generator, and fire up the the generator and the house is powered (limited of course to the generator wattage). It's enough to run a refrig, a gas furnace, and bunch of lights and tv. The noise of the generator is away from the house in the garage.

Enter RV'ing. I just made a dongle with a 240v 30amp male, connected to a 240v 50amp female. I made it long enough so the weight of the 50amp connectors with the coach shorepower was laying on the garage floor. Used 10 gauge cable, since it's on a dual 30amp circuit breaker in breaker box.

Since you aren't 100% certain how they wired that existing socket in the house though, just check it out with a voltmeter to make sure it's what you think it is. Two separate 120v legs, with a neutral and ground. You can additionally verify by taking the cover off the house breaker box, and see how that wire is connected to the buss bars and a dual breaker.

[twinboat]

Here is a shopping list, you don't need to cut up an adaptor.

https://www.amazon.com/Camco-55353-F.../dp/B00192QB9M

https://www.amazon.com/dp/B0014KO11O...a-273536540827

[NevadaNick]

Follow what Twinboat is telling you. Easiest and its right.

[Isaac-1]

In theory yes, but those Camco female ends are a pain to wire, you have to splice the wire to just the right length and then it barely fits under the cover. A surface mount outlet box would likely be much easier with more room to work inside.

[hypoxia]

Wow, a simple question and a lot of mis-information!

An adapter like that may come in handy if you stay at many private homes. I have several dryer cords and may make one.

As Nothermark says, just check the power with a meter first.

[twinboat]

Originally Posted by Isaac-1

In theory yes, but those Camco female ends are a pain to wire, you have to splice the wire to just the right length and then it barely fits under the cover. A surface mount outlet box would likely be much easier with more room to work inside.

I suggested that end because the OP was looking for a weather resistant connector.

[Gary RVRoamer]

The problem with a 3-prong 30A/220v outlet is that is lacks a neutral, i.e. only 220v is provided via the two hot terminals. There is no way to get 2x 120v circuits from it to feed to your 50A RV plug and RV power system.

If its a 4-prong outlet, it has 2x 120v/30A hot terminals plus a neutral and a ground, and that will work fine. Odds are your 4-prong power cord will plug right into it. You have 30A per "leg" and that is typically enough to run everything in a 50A powered RV that has a max of two a/c units.

[wa8yxm]

First. There are two concerns. IF that dryer outlet is a 4-Wire outlet then it MIGHT be possible to use it for RV use, Instructions will follow two ways.

NOTE the key words are "4 wire" and "might"

First, inspect the wires, is the NEUTRAL the same gauge as the HOT wires, YES, good, Smaller, not good. Do not use.. Explanation follows instructions.

Now Assuming it is: Will your plug fit.. YES done NO you need an adapter here is how to build it

You will need
Dryer power cord
50 amp RV outlet
Box and cover

Verify ify all leads before you close up the box HOT to the sides, Safety to the round, and neutral to the remaining flat slot.

Why must the neutral be the same size for RV use but not for dryer?

Dryers use both 120 and 240 volt Some things like the timer motor and the motor that runs the blower and turns the drum are often 120 volt.. If there is a light it is 120 volt.. The heat element is the only 240 volt, So where the heater draws enough to need 30 amp lines, well the rest of it, less than 10 amps.. So the neutral is often smaller since it only needs to carry the 10 amps.

But on the RV. Depending on what A/C you are using and how other things are wired.. Well drawing the full 30 amps on just one leg without any load on the other is very possible,,, and if this happens the neutral will carry the difference, (Full 30 amps) and that will put it in overload if it is too small.

So make sure the neutral is the same size.

NOW: if the dryer has a 3 Prong outlet.... DO NOT USE. period.

[distaff]

Getting some good suggestions. I may stay away from the Camco end if it is a pain to work with since I'll make a short adapter out of a dryer cord. I've only ever encountered this in a domestic situation. In this case my friend has the outlet in his shop and it was installed for a welder.

One other point - I am mindful of power loss and heat build up over a long cord, so I don't plan to try and run the dryer or more than one AC unit when running a 50 foot extension.

[wa8yxm]

If you need to make up a 50' or longer cord, UPSIZE the wire (Though in truth a 50 amp cord is likely heavy enough)

I might add, if you can adapt to the outlet and if the outlet IS a proper 4 wire outlet.. 30 amps runs both A/C's easily..

As for the advice to not run more than one A/C on a long cord.

Again, if you are hooked to a proper 120/240 outlet (4 wire) then the strain on the system from BOTH A/C's is no different than from one, and in fact the voltage loss is LESS, believe it or not..
If pressured I can explain why.. It is face palm for those of us who know electricity/electronics but can be confusing for those who do not, I do my best to clear the mud.

Short version: Let us assume a 2 Volt Drop each way

RUnning one 120 volt A/C you have 2 volt out, 2 back and the thing is running on 116,, No problems

Running two on a proper 120/240 volt 4 wire circuit
You have two volts out.. but the 2 volts back are on the other A/C so the voltage is now 118, not 116.. Half the voltage drop.

WHY, because in that configuration the NEUTRAL is not doing anything but sitting there. and that's where half the voltage drop was.. You are literally using each amp twice. once on each leg.