Using Dryer's NEMA 14-30 outlet for RV shore power

[audiodane]

Hey folks,

UPDATE:
Skip all the banter and jump to the CURRENT PLAN using this link!

Original Post:
I've been reading lots of posts about using dryer hookups for RV shore power at home and lots of them are outdated (using the older NEMA 10-30 outlets). This question is about the newer NEMA 14-30 hookups.

(Edited to add this DISCLAIMER: For the sake of clarity, I am a degreed electrical engineer with ~20yrs experience and have worked around electricity my entire life. I have done plenty of wiring jobs at my own house and at the houses of friends and family. I understand electricity and the risks involved significantly well. I do plenty of electrical work, but do draw the line at installation of a new subpanel or main service entrance. 🙂 I believe this thread is entirely useful for others who may wish to install a NEMA 14-50 outlet in their garage (whether for their RV or their Tesla). But, if you are not qualified to work on electrical systems, PLEASE do not take this thread as a suggestion that such a job is easy and without significant risk. I will not, nor will any other contributor to this thread, be responsible for anything you do as a result of this thread.)


For reference..

OLD style:
Link: Wikipedia NEMA 10 Style
Example:


NEW style:
Link: Wikipedia NEMA 14 Style
Example:


My house (build circa 2007) has the newer style NEMA 14-30 connector. When I put a multi-meter on it, it measures like this:



That seems to me equivalent to the necessary 50A hookup on an RV (albeit with only 30A's "actual"):



It also seems to me that I could use a 2-phase (DPDT) 30A switch to switch between my dryer outlet (inside) and a RV outlet (garage), using a switch such as the Leviton 1288 to switch power between the dryer and the garage outlets.

Leviton 1288:


However, I read over and over about people frying their RV trying to hook up shore power various ways from their house. SO I wanted to try and clarify what I think would work and get feedback.

It seems to me that I can use my dryer dual-30A hookup to power a 50A RV hookup with the stipulation that it will be limited to 30A per leg at the breaker box.

To be clear, our goals would be:

• Park the RV in front of the house before/after trip for loading/unloading
  
• Have Lights, A/C, and fridge running while loading/unloading
  
• *NOT* planning on daily living use (microwave, etc)
  

It would seem to me that this circuit would be able to do the job.

My plan currently is:

• Turn off dryer circuit breaker (safety first!)
  
• Disconnect existing circuit from dryer outlet
  
• Connect circuit from breaker to a DPDT switch such as the Leviton 1288 (linked above)
  
• Connect one set of switch outputs to Dryer outlet
  
• Connect second set of switch outputs to Garage RV outlet
  

Lastly, I want to again point out that this scenario would only supply 30A to each 120V leg even though we would be using a 14-50 style 50A RV hookup plug. This limitation comes from the breaker box itself. I cannot replace the breaker with a 50A because it would involve pulling new 50A wiring, and might violate dryer safety.

So, ..... thoughts?

cheers,
..dane

[sayoung]

audiodane wrote:

Learjet wrote:
sounds like you are on the right track, just remember that you will need to be able to turn the power off to connect and disconnect....sounds like the outlet will be below the panel...so that should make it easy.

Ohhhh, I *had* forgotten about that. Yes, easy enough to just post a big placard that says "STOP! Flip breaker off before plugging/unplugging!" ....

It would be kind of nice though if there was a drop-down cover at acted like a switch. Lift the cover to insert- power cut. Lower cover, power on. Lift cover to remove plug, power cut.

But until then, a big red stop sign placard hanging on the breaker box should be fine. My kids would probably love to make it for me, too. 🙂

..dane

HomeDepot has a box with 50 amp plug, 120V gfci plug, & breaker ( use for cutoff ) for &120 or a box with 50/30 rv plugs & gfci plus breaker for more.. I was going to use one of thsse when I built our RV shed but was able to get my main panel within 7 ft of my plug. I was having to work my buried feeder around existing septic system and got lucky .

[audiodane]

Learjet wrote:
sounds like you are on the right track, just remember that you will need to be able to turn the power off to connect and disconnect....sounds like the outlet will be below the panel...so that should make it easy.

Ohhhh, I *had* forgotten about that. Yes, easy enough to just post a big placard that says "STOP! Flip breaker off before plugging/unplugging!" ....

It would be kind of nice though if there was a drop-down cover at acted like a switch. Lift the cover to insert- power cut. Lower cover, power on. Lift cover to remove plug, power cut.

But until then, a big red stop sign placard hanging on the breaker box should be fine. My kids would probably love to make it for me, too. 🙂

..dane

[sayoung]

wnjj wrote:

audiodane wrote:

sayoung wrote:
Please don't use anything made by Siemens , its junk from my experience with their breakers/panels.

Oh, really? I had not heard this. Hmm. Okay.

Well then I'll go the approach of replacing 4x 15's and/or 20's with tandems, and then get a double-50 as was recommended by others.. local hardware stores carry Square-D which I know many people often recommend..

thanks!

From what I gather, Siemens and Square D is a Ford/Chevy thing for some. Use whatever your panel requires as there are different styles. Pull an existing breaker and take it with you to be sure.

When I was working I replaced lots of Siemens breakers, they should change the spelling . CH, GE, SqD & SqD homeline did quit but not often. SqD Disconnects most trouble as it uses a switch that looks like a breaker so after not being turned off after10 years of working and the repair guy turns it off to work on equipment, it won't reset. Be glad you don't have a Federal Pacific panel trying to do this .

[Learjet]

sounds like you are on the right track, just remember that you will need to be able to turn the power off to connect and disconnect....sounds like the outlet will be below the panel...so that should make it easy.

here is one of the three 50 amp outlets I have installed at my property 🙂

[audiodane]

wnjj wrote:

From what I gather, Siemens and Square D is a Ford/Chevy thing for some. Use whatever your panel requires as there are different styles. Pull an existing breaker and take it with you to be sure.

Ahhhh, okay. Thanks @wnjj. I have the seimens on order. once I actually get in there in the next couple of days/weeks I'll have a look and see what brands are in there and if the siemens fits/works or not..

Might be a few days before I get back to it while I wait for outlet and stuff to arrive...

[wnjj]

audiodane wrote:

sayoung wrote:
Please don't use anything made by Siemens , its junk from my experience with their breakers/panels.

Oh, really? I had not heard this. Hmm. Okay.

Well then I'll go the approach of replacing 4x 15's and/or 20's with tandems, and then get a double-50 as was recommended by others.. local hardware stores carry Square-D which I know many people often recommend..

thanks!

From what I gather, Siemens and Square D is a Ford/Chevy thing for some. Use whatever your panel requires as there are different styles. Pull an existing breaker and take it with you to be sure.

[audiodane]

sayoung wrote:
Please don't use anything made by Siemens , its junk from my experience with their breakers/panels.

Oh, really? I had not heard this. Hmm. Okay.

Well then I'll go the approach of replacing 4x 15's and/or 20's with tandems, and then get a double-50 as was recommended by others.. local hardware stores carry Square-D which I know many people often recommend..

thanks!

[sayoung]

Please don't use anything made by Siemens , its junk from my experience with their breakers/panels.

[Learjet]

wnjj wrote:
With that many normal sized breakers, it may be less expensive to tandem four of them into 2 slots and then install a standard 50 double pole breaker. Have you pulled a breaker to see if they will support tandems?

yep...that was my first thought too..double 15 or 20 amp as applicable.

https://www.amazon.com/Square-Schneider-Electric-HOMT1515CP-Single-Pole/dp/B00002NB47/ref=pd_bxgy_60...

[audiodane]

Gdetrailer wrote:
As far as the OPs setup, the only issue I see with the double breakers is many boxes which do accept those breakers do not have enough ground and Neutral buss bar connections. This may require doubling up on the ground and Neutral wires on the buss bars. Some electrical inspectors may be OK with that and some may not.

Checked.. PLENTY of open neutral connections on both panels... 🙂

thanks!

[audiodane]

sayoung wrote:
I misunderstood where your dryer plug is, when you said on other side of garage I was visualizing 15 to 20 feet away. If those are GE-Homeline style breakers ( photo fuzzy ) , replacing with thins might be cheaper than the quad style. Lowes sales the GE Qline 30 & 50 dbl's for less than $10 ea. Thru the years the GE style "thins " gave me very little trouble and I' ve installed a many on the job , when I worked:B

wnjj wrote:
With that many normal sized breakers, it may be less expensive to tandem four of them into 2 slots and then install a standard 50 double pole breaker. Have you pulled a breaker to see if they will support tandems?

I think y'all are saying the same thing... You mean replace four single-wides with two tandems, and that frees up a double-spot for an inexpensive double-wide 50A.

It looks like from HomeDepot a tandem 20A is around $10, a tandem 15A is around $8, and a double-50A is also around $10. The Siemens quad from Amazon is about $30 so it looks more or less like a price wash....

Oh, but look, the Siemen's 20/5050/20 version (as opposed to 15/5050/15) is available for $23... Woot! Gonna cancel the $30 15/5050/15 and order a 20/5050/20 since I have 20A neighbor pairs also available...

[wnjj]

With that many normal sized breakers, it may be less expensive to tandem four of them into 2 slots and then install a standard 50 double pole breaker. Have you pulled a breaker to see if they will support tandems?

[sayoung]

I misunderstood where your dryer plug is, when you said on other side of garage I was visualizing 15 to 20 feet away. If those are GE-Homeline style breakers ( photo fuzzy ) , replacing with thins might be cheaper than the quad style. Lowes sales the GE Qline 30 & 50 dbl's for less than $10 ea. Thru the years the GE style "thins " gave me very little trouble and I' ve installed a many on the job , when I worked:B

[Gdetrailer]

stevemorris wrote:

sayoung wrote:

Learjet wrote:
As I said in post #2 do it right and add the circuit. The double 240 or if you have some single 120 CBs you can get those in double to make space for another standard 240 breaker. 🙂

I had a thought , the 3rd wire on the dryer is not normally a current carrying wire but actually safety gnd so I wouldn't piggy-back these outlets. Maybe I was taught wrong years ago when gnd added to wireing code , was taught to never use the gnd for current carrying, it's there for protection.

this is incorrect. Both driers and stoves(household types) require the 120 as well as 240. Remove the neutral and they wont work. the control boards, clock, motors etc etc require 120, hence the neutral

Drier circuits at one time it WAS acceptable to wire with NO Neutral (AKA "three wire") with two hot and one GROUND.

The drier motor and timer are 120V and did indeed use the GROUND WIRE in order to get the needed 120V to operate.

The EXISTING three wire drier circuits are "grandfathered" and are still allowed, you cannot how ever install a three wire drier circuit in a new installation.

NEC made the change a few yrs back to require FOUR wire drier circuits in order to eliminate the potential issue of current being carried on the SAFETY GROUND WIRE. So, new drier circuit installations now require four wire 240/120V..

Driers ARE designed to be able to be setup for 3 wire OR 4 wire via a removable jumper between the safety ground connection and the Neutral connection on the drier terminals.

As far as the OPs setup, the only issue I see with the double breakers is many boxes which do accept those breakers do not have enough ground and Neutral buss bar connections. This may require doubling up on the ground and Neutral wires on the buss bars. Some electrical inspectors may be OK with that and some may not.

I will toss in an additional idea..

Add on a small manual generator transfer panel, feed the transfer panel via a 100A 240V double pole breaker from the main panel, move a few "critical" house circuits to the transfer panel. This will now free up some spaces to put your RV 240 breaker and give you the option for a generator power backup system.. Kill two birds at one time..