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House RV Plug-- 30 Amp

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Once again, I will post the definitive source for RV Electric Supply answers. There are pictures (worth a thousand words), diagrams, wiring size tables, etc. This link even has a page for you to print and give to your electrician. This is especially important if your electrician is asking questions. The fact that he is asking questions is a really good sign. That's a smart electrician, keep his phone number on your list for any electrical problems!

This is RV Electric. Bookmark it for future reference.

Just for grins!

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As Herman said, on the subject. In Colorado, in Summer, I have had to use 30 amp and found no problem with it. Warm days, cool nights...in Texas, I would go with 50 amp.

As Jim S said, "get another electrician"!

My 2 cents worth.... :D

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I know this is an older thread, but thought I'd give a little info, in case anyone else is looking here to do this.  Shortly after I got my MH (2006 Winnebago Aspect 26A ... 30 Amp), I installed a 30 Amp RV receptacle on the side of my house where I park my RV. 

I tapped into the Dryer Circuit, which happened to be on the opposite side of the garage wall from where I park the RV and wanted to place the outlet.  I drilled a hole thru the cinder block, just a few inches from the Dryer outlet.  Killed the power, then connected wiring to just one side (leg) of the Dryer circuit, (being certain I was only getting 120v not 220v).  Ran heavy gauge wire thru conduit out to the box I put on the outer wall, then wired in the 30A outlet and ran a little more wire further to give myself a regular 20A home outlet (outdoor) as well (to use for other things). 

After all done, I tested again to be absolutely certain I had 120v at the new outlets on the outside wall.  This gives me very heavy gauge wiring back to my breaker panel (by means of the already existing dryer wire) and I put pretty heavy wiring for the 1.5 to 2 feet of wire from the dryer outlet to the new outlet. 

The only caveat is I feel to not overload, the A/C in the RV and the Dryer itself, should not be run at the same time.  Simple enough to be sure of.

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Sounds like this is working for you, but I'd suggest that it would be better to run the 30-amp service for the RV outlet from a dedicated 30-amp breaker in your load center. Piggy backing on another circuit, especially tapping 120v from a 240v circuit like this, just leaves too many possibilities for future problems and safety hazards. I'm no electrician, but I'd place money on it being a violation of the code in your area as well.

If it's not possible to run new wiring for the RV outlet all the way to the main load center, then perhaps you can put a small sub-panel where the dryer outlet is currently located and then use that to power both the new RV outlet and the dryer outlet. You're trying to use the dryer outlet as a sub-panel, but it's not designed for this and doesn't give you the ability to place a breaker for the RV outlet. Using a sub-panel instead of piggy-backing would give each its own breaker. You could likely still use the wiring that previously serviced the dryer outlet to power the sub-panel, but you'd have to first check to see the rating/size of the wire.

Sorry to rain on your parade.

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10 hours ago, QuiGonJohn said:

I know this is an older thread, but thought I'd give a little info, in case anyone else is looking here to do this.  Shortly after I got my MH (2006 Winnebago Aspect 26A ... 30 Amp), I installed a 30 Amp RV receptacle on the side of my house where I park my RV. 

I tapped into the Dryer Circuit, which happened to be on the opposite side of the garage wall from where I park the RV and wanted to place the outlet.  I drilled a hole thru the cinder block, just a few inches from the Dryer outlet.  Killed the power, then connected wiring to just one side (leg) of the Dryer circuit, (being certain I was only getting 120v not 220v).  Ran heavy gauge wire thru conduit out to the box I put on the outer wall, then wired in the 30A outlet and ran a little more wire further to give myself a regular 20A home outlet (outdoor) as well (to use for other things). 

After all done, I tested again to be absolutely certain I had 120v at the new outlets on the outside wall.  This gives me very heavy gauge wiring back to my breaker panel (by means of the already existing dryer wire) and I put pretty heavy wiring for the 1.5 to 2 feet of wire from the dryer outlet to the new outlet. 

The only caveat is I feel to not overload, the A/C in the RV and the Dryer itself, should not be run at the same time.  Simple enough to be sure of.

I think the problem would be there is no common wire.  A drier has two hot legs with a ground. When you take one leg and the ground you do have 120v but you don't have a common (white) to complete the 120v circuit.

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6 minutes ago, desertdeals69 said:

I think the problem would be there is no common wire.  A drier has two hot legs with a ground. When you take one leg and the ground you do have 120v but you don't have a common (white) to complete the 120v circuit.

True if you have an older dryer connection. I think that around here code is now a 4-wire connection for dryers, so that would add even more confusion. It gets yet more confusing if someone mixes 3-wire and 4-wire systems together (older dryer with newer outlet, for example). Always best to confirm with an electrician if there is any doubt.

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What amperage is the dryer circuit breaker, and what size is the wire away from that breaker? These questions need to be answered in order to determine is this is problematic or not. To run 30 amps off of this circuit, the breaker will need to be 30 amps at 240 volt, which is a dual pole 30 on each leg. Depending on how long the run is from the breaker, #10 gauge for a short run will be sufficient, but over 100 by code, but I will not run more than 50 for personal reasons, and remembering that the dryer plug can no longer be used as a dryer plug, meaning that the plug itself will need to be removed, I personally would prefer that #8 wire be used all the way back to the CB. Next to consider is that the wire from the CB does need to be 3 conducter plus ground as Richard stated, also the 20 amp circuit extension needs to be wired to the other side of the 240 volt plug, so not overload the 30 amps available on the 30 amp leg. And to do this conversion properly, with the steps above achieved, the dual 30 for 240 volts needs to be changed out to two individual circuit breakers one for 30 amps and one for 20 amps if using a true 20 amp receptacle. Not following these cautions is a fire waiting to happen. Best scenario is to replace the dryer plug with a two breaker box and wire the two new receptacles with two circuit appropriate breakers from here. If this is done in this manner, the new breaker box can have a correct dryer 30 amp male plug in and plugged directly into the existing outlet, then unplug the add on if the dryer needs to be used. Not to code, but if only three wires, a ground rod could be driven outside and attach the ground for the breaker box to the ground rod.

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To code or not...safety is always on my mind around electricity, my coach at Linda's and 3 other friends is on designated 50A...all put in by a licensed electrician.  All 4 connections are on ranches' out side the city limits!  Not cheap, but safe.  Those circuits are also backed up by the main house and barn generator, should there be a loss of electricity. 

   

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On 7/17/2014 at 6:50 AM, hermanmullins said:

OK, folks lets get back to the original question. "A 30 amp RV outlet is 110 volts only NOT 220 volts." Gayle please pass this on to your electrician.

Herman

Agree.  There have been quite a few instances where sticks and bricks electrician has caused serious problems when wiring for an RV.  I'd be sure the electrician understands what how our systems are wired.

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Correct-- 30 amp RV outlets are 120 VAC, not 240.  So ONE Hot, one neutral and one ground.

Yes, many newer home dryer outlets do have a neutral, but many older ones DO NOT (have two hots and a ground).  Wiring an RV outlet to one of these older connections will "let the smoke out" of many systems in an RV, because they are 240 VAC.

So, with a newer dryer outlet AND a smart electrician who connects to only one hot and the neutral and ground, it can be done.  Otherwise...poooooffff.

50 amp RV outlets ARE 240 (two hots, a neutral and a ground).

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So this circuit is 30 amp, the breaker is a 30 amp breaker.  The dryer's outlet box was grounded and I connected that ground to the ground for the TT-30R receptacle I put for the RV.  I just tested the voltages again and they are proper at the RV receptacle.  Interesting to note that the dryer receptacle does not have a connection for a ground lead.  But I think it is grounded by how it attaches to the metal receptacle box when the receptacle itself is properly screwed into the outlet box, then that is passed to the ground wire which goes off into the conduit that feeds this receptacle box. 

We mostly don't use the RV while parked there.  But I like to keep it plugged in for the house batteries (I put in an advanced converter/charger not too long after I bought the RV). 

Also, so that I can keep the A/C on to protect electronics from Extreme Heat.  I keep the A/C set, when we are not in there and it is just parked, at the highest setting, 98°.  Warm for people, but fine for electronics.  We put in a new TV a few years back and the first one died prematurely, (exchanged under warranty).  At the time we were not keeping the A/C on.  Well I researched it and the manuf of the TV indicated the max temperature for it to be exposed to (when not in use) was 125°.  Did it get that hot in there before we started keeping the air on?  Maybe, maybe not.  But now, keeping it at a max of 98° should prevent damage to it or any other electronics.

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Was the dryer outlet a 3-wire or a 4-wire? If only 3-wire, then where did you get the neutral for the RV 30-amp connection?

Do you have a plug-in outlet tester? If you have one of these then you can plug into any outlet in the RV and be certain that the ground is proper and that you have both hot & neutral connected to the proper sides. For around $5, these little devices are really cheap insurance. The volt meter will check for proper voltage, but these devices will tell you much more.

Sounds like you're trying to be thorough and do this safely, but it never hurts to have things double checked.

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X2.  Don't want to hear about a coach/house or both going up in flames, due to improper electrical connection!  Your TV and electronics, like 80 or less, more than 98.

I got 3 of those plug ins.  Linda has about a dozen & uses them all over the ranch and her coach.

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Richard, the Dryer has 3 wires to the receptacle, Hot 120v on leg, Hot 120v other leg and Neutral.  It also uses a physical ground.  I connected my circuit using one hot leg and the neutral, as well as a ground connected to the ground wire inside the receptacle junction box.  I wired this years ago, probably 2013 and it has been fine.  Unless the A/C is on, we are most likely not pulling much amperage at all in the RV, with everything off and the batteries on a float charge.  But just to be safe, I make sure the A/C is not running when we use the dryer in the house.  I will look into picking up one of those power tester plugs, as it is probably easier than trying to get the meter probes into sockets, sometimes.

manholt, the TV specifically states under 125° if it is just ambient temperature, TV not on, no power to it

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Dryers for the last 45 years that I know of have been 4 wire 

all things in the unit are 115 volt so they split use the  220 with the neutral so they did not need a 60 amp 115 volt breaker and heavier wire  

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27 minutes ago, bm02tj said:

Dryers for the last 45 years that I know of have been 4 wire 

all things in the unit are 115 volt so they split use the  220 with the neutral so they did not need a 60 amp 115 volt breaker and heavier wire  

If my information is correct, the code only changed about 20 years ago. Around here many homes are still running 3-wire dryer outlets. There is no requirement to upgrade the outlet when a new dryer is installed, so the 3-wire setups will probably be in use for a long time. Many of the 3-wire dryer setups use a neutral/ground bond.

It's good that the connection is working for you, but my concern and reason for bringing all this up is that there exists possibility for safety issues if someone else tries this approach to get power to an RV. My first concern would be whether or not there is a neutral-ground bond installed at the dryer and how that would affect the 120v circuit that is piggy-backed to the 240v circuit. My second concern is whether this setup would allow one side of the dual 30-amp breaker to trip properly if something on the RV side drew too much current or if there was a catastrophic failure (like the cordset being damaged, etc). I'm not saying it wouldn't trip, just that I'd want to verify the safety with an electrician first before trusting this breaker to provide protection.

 

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