Adapting a 14-30 Dryer Outlet for a 30 Amp RV

[RVcurious.]

Curious if this wall outlet I had installed in my garage needs to be changed out or if it can be adapted to fit my 30 amp plug (couldn't source out any dogbones, etc. online) . As the electricians installed it I didn't think too much of it at the time. It's upside down as well. It says on the face 30amp/125/250 .

Need some help on this puzzle,
Thank you.

 

[bigbAZ]

You need a 30 amp 120V outlet, 1 hot, 1 neutral and 1 ground. If there is a neutral present, which there should be connected to the "L" slot, a 50 to 30 amp dogbone will hook you up. Camco makes one.

See below post #5

 

[RVcurious.]

Thanks for that. I will get back to you if you don't mind, I may have further questions.

 

[bigbAZ]

If the electrician won't come back to flip the outlet, and if you feel confident, test the outlet first to verify the tester is working, shut off the power then test the outlet again to verify it's dead, then test a known live circuit with the tester again to verify it is still working. Then remove the outlet, carefully rotate it into position, then re-tighten the terminal screws and install the outlet.

Any good electrician should be willing to come back and flip it to the proper orientation, I don't know why some put them in like that, inexperience I would guess. I have yet to see a 50 amp 90 degree plug where the ground is on the bottom.

See below....

 

[bigbAZ]

oops I goofed, you have a 30 amp 120/240. You will need to have the electrician change the outlet to a TT30
This could get sketchy if he doesn't understand you need 120 volts. Make sure he connects only one of the hots to the TT-30 or you will have big problems. 1 hot, 1 neutral, 1 ground.

If I recall there are adapters for that but not sure I'd trust one without testing it for 240V. Here is one: https://www.lowes.com/pd/AC-WORKS-1...-RV-Adapter/5013206747?user=shopping&feed=yes

 

[DutchmenSport]

If that plug is inside your house, it's wired for 240 volts.... even with that adapter, you do not want to plug your camper into it. That socket looks like either a 240 volt electric dryer plug, or a 240 volt electric stove/range/oven plug.

The wires leading to that plug can be moved around with the appropriate RV socket to accommodate a 50 amp RV plug and THEN that adapter can be used to step down to 30 amp for your 30 amp camper.

Absolutely do not plug your camper into that plug as it's set up the way it is right now. Get an electrician and have it set up. Since everything is there for a 240 volt set up, with the 50 amp RV socket, it will be easy to switch over. The RV plug will have 2 legs of 50 amp available. The adapter will pull power from one side only, and if your camper exceeds 30 amps usage, the main breaker in your camper will pop, not one in your house. It will not pop until the circuit exceeds 50 amps.

Do the right thing, get an electrician and get the right plug. Again... do not plug the camper into this the way it's wired right now.

My correction: The amount of amps available at that plug are determined by the breaker inside your breaker box. If the breaker is a double 30 amp breaker, you have 2 legs of 30 amp. If you have a 50 amp double breaker, then each leg will have 50 amps.

I had a 50 amp RV socket installed at my house. The actual breaker box at the plug is a 50-50. However, that box is wired to an 80 amp breaker inside the main divider box, which separates a line to the garage and a separate line to the house. The RV box also has a 30 amp and a 20 household amp socket. That's why is wired farther upstream to an 80 amp breaker.

So check the breaker in your breaker panel.. If it's 50 or if its 30. If it's 30, you can go ahead and install a 30 amp RV socket and just use only 1 side and forget that adapter.

 

[RVcurious.]

I appreciate it, I was suspicious in the first place. Makes complete sense. Thank you for being thorough. I wasn't about to plug whatever into that socket anyway.

 

[bigbAZ]

If that plug is inside your house, it's wired for 240 volts.... even with that adapter, you do not want to plug your camper into it. That socket looks like either a 240 volt electric dryer plug, or a 240 volt electric stove/range/oven plug.

The wires leading to that plug can be moved around with the appropriate RV socket to accommodate a 50 amp RV plug and THEN that adapter can be used to step down to 30 amp for your 30 amp camper.

Absolutely do not plug your camper into that plug as it's set up the way it is right now. Get an electrician and have it set up. Since everything is there for a 240 volt set up, with the 50 amp RV socket, it will be easy to switch over. The RV plug will have 2 legs of 50 amp available. The adapter will pull power from one side only, and if your camper exceeds 30 amps usage, the main breaker in your camper will pop, not one in your house. It will not pop until the circuit exceeds 50 amps.

Do the right thing, get an electrician and get the right plug. Again... do not plug the camper into this the way it's wired right now.

My correction: The amount of amps available at that plug are determined by the breaker inside your breaker box. If the breaker is a double 30 amp breaker, you have 2 legs of 30 amp. If you have a 50 amp double breaker, then each leg will have 50 amps.

I had a 50 amp RV socket installed at my house. The actual breaker box at the plug is a 50-50. However, that box is wired to an 80 amp breaker inside the main divider box, which separates a line to the garage and a separate line to the house. The RV box also has a 30 amp and a 20 household amp socket. That's why is wired farther upstream to an 80 amp breaker.

So check the breaker in your breaker panel.. If it's 50 or if its 30. If it's 30, you can go ahead and install a 30 amp RV socket and just use only 1 side and forget that adapter.

That is a 30 amp 120/240 (clothes dryer) outlet so the breaker should be a 2 pole 30. The adapter from Lowes will probably work but I would test it first to make sure they used only 1 hot and a neutral, you never know how they get put together by the unaware. A 4 wire dryer outlet is wired the same as a 50 amp RV outlet (they are both 120/240) except it is limited to 30 amps and has the L slot instead of 3 straight slots.

 

[Kirk]

if it can be adapted to fit my 30 amp plug (couldn't source out any dogbones, etc. online) .

Absolutely no. As a retired electromechanical technician, I can tell you that you have a 250V, 30A outlet and there is no adapter to serve your 120V, 30A RV. The problem is not the amps but the volts. Just keep in mind that the people advising you on how to use it won't be the ones trying to fix your RV after you plug it in. Get a qualified electrician and make sure that he knows what your RV needs in both connections and voltage.

 

[bigbAZ]

Absolutely no. As a retired electromechanical technician, I can tell you that you have a 250V, 30A outlet and there is no adapter to serve your 120V, 30A RV. The problem is not the amps but the volts. Just keep in mind that the people advising you on how to use it won't be the ones trying to fix your RV after you plug it in. Get a qualified electrician and make sure that he knows what your RV needs in both connections and voltage.

 

[DonTom]

I can tell you that you have a 250V, 30A outlet and there is no adapter to serve your 120V, 30A RV. The problem is not the amps but the volts.

Perhaps with a step down transformer but then will still need the correct adapters.

-Don- Reno, NV

 

[John From Detroit]

If the outlet is properly wired yes it can be adapted but I don't know the current rating (you get only one leg.

If the outlet is not properly wired and that is frequently the case. DO NOT DO IT.

I don't want to get into what is proper or not but it need 4 wires.
Two hot (each side) and a neutral ("L-shaped" slot) all the same size.

Ground (Round hole) Size depends on things I do not know but it's often smaller.

 

[Lou Schneider]

View attachment 2463087

Note the shape of the ground pin. It's round while the socket has an L-shaped ground.

The L-shaped ground is for an appliance that draws most of it's current across the 240 volt pins, the neutral may be undersized for something like a 30 amp RV that draws all of it's current from one leg and returns it via the neutral.

I'd get an electrician involved and let him see what is needed to safely plug an RV into that circuit. You'll definitely have to change out the outlet and you may have to upgrade the wiring feeding it. Not a job for an amateur.

 

[bigbAZ]

Perhaps with a step down transformer but then will still need the correct adapters.

View attachment 2463102

-Don- Reno, NV

No need for a step down transformer! A 14-30 has the necessary 120 volts needed for a 30 amp RV.

 

[bigbAZ]

This is really quite simple, it is no different than using a 50 amp to 30 amp dogbone on your RV at the RV park except in this case it would be a 30 amp to 30 amp. If the 14-30 was wired with Romex the neutral will not be undersized, and if it is in conduit it would not be allowed to be undersized in a dwelling unit. Reduced sized neutrals are only allowed in industrial settings with engineering approval and on site supervision, and in listed cables/cords and assemblies.

He already said an electrician recently installed the circuit, if it was installed with 10/3 W/G Romex he is good to go with the dogbone sold at Lowes. As I said earlier I would still test the dogbone to make sure it is wired correctly before using it.

Alternatively the 14-30 could be replaced with a TT-30 and one of the hots capped off. This is where the individual doing the work should be qualified and aware that a TT-30 is 120 volts.

The L shaped slot is the neutral, not the ground. The ground is a round pin just like on a 14-50. (In the OP's photo the 14-30 is installed upside down)

 

[Wmlunt-WO]

Totally agree! 40+ years of machine design I know you should get an electrician involved!
If you mess it up, and manage to live thru it, your insurance will not cover the fire from negligent wiring practice by unlicensed wiring practice, or your neighbor if the fire spreads that far!
Bill

 

[Arch Hoagland]

Danger, Will Robinson!

DO NOT USE THAT OUTLET.

Don't use it until you have actually measured the voltage and know for sure you have 120 volts.

Not all electricians are familiar with RV outlets. If I was you I'd hire an electrician who knows what he's doing as there have been many people on here who plugged into those 220 outlets and destroyed a lot of stuff in their RV's.

 

[NY_Dutch]

The 14-30P to TT-30R adapter posted by bigbAZ is the correct one to use. As posted, it's just the 30-30 amp version of the 50-30 adapter used with 14-50 outlets commonly used in campgrounds, for ranges, ovens, and high capacity dryers. No transformer needed...

 

[DonTom]

I'd get an electrician involved and let him see what is needed to safely plug an RV into that circuit. You'll definitely have to change out the outlet and you may have to upgrade the wiring feeding it. Not a job for an amateur.

Since the required output is 120 VAC for an RV30, why not forget about the electrician and just use the transformer I mentioned and than not care about the neutral? Will cost less than the electrician and then have the option of using either.

Still need to get the correct adapters.

-Don- Reno, NV

 

[DonTom]

No need for a step down transformer! A 14-30 has the necessary 120 volts needed for a 30 amp RV.

True about perhaps no need.

But . . .

But you get very close to double the power (watts) out by using both legs instead of one leg to neutral. Only loss is at the transformer. Typical transformer efficiency is above 95%. That beats 50% not being able to be used at all. IOW, convert that extra unneeded voltage to current which can be used with the step down transformer (--for voltage-- which means step up the current capacity).

Then can than ground either side at the 30-amp RV frame. I noticed my old 4k Onan genny (removed) had one leg going to the frame where the shore power neutral is tied down (from the factory) on my Y2K motorhome.

Anyway, that is the way I would have handled it. Is there anything considered unsafe about the DonTom method by electrician standards?

Cheaper than hiring an electrician, more power available, more choices. The only downside is getting or making the adapters if cannot find a transformer that has the correct stuff already.

-Don- Reno, NV