50 amp electric wiring from breaker

[LRKDRV7.3]

I have a 2009 DRV Elite suite

So a 50 amp rv has 2 50 amp hot leads.......so in phase or out of phase..... if in phase is 220.....right? Every one says 220 will fry rv electrical.....how do i get 2-50 amp legs from breaker panel without being 220?

[GlennWest]

Al America service is 120 volt. 2 legs of 120v come to your electrical box. Only time you have 240v is you use a breaker to bridge the two legs. Your rv likely has no 240v appliance so you only have 120v. If you go to your power pedestal and hook a meter to both hot legs you get 240v. If you connect to neutral and 1 hot leg, you get 120v. This is the way your house and rv work. 

[oldjohnt]

1) A 50 Amp RV has two UnGrounded legs L1 & L2 each of which is 120 VAC with respect to the Grounded Common Conductor Neutral.........

2) Such an RV Park electrical service if wired as most (but not all) are is referred to in the trade as 120/240 Single Phase Three Wire.

3) If such is indeed the case and is typically how most homes are served, L1 & L2 are 180 out of phase with each other (when one is 120+ other is 120-) THEREFORE its 240 VAC L1 to L2.

4) Soooooo you see there is 240 VAC in that 50 Amp RV electrical panel if you measure across L1 to L2 BUT ONLY 120 (1/2 that) from EITHER L1 orrrrrrrrrrrrrrrr L2 to the Common Neutral  

5) The way such a service is derived is using a transformer which has a LV Secondary winding which measures 240 VAC end to end L1 to L2 HOWEVER in the center of that LV secondary winding is a center tap which becomes earth grounded and is Neutral so its only ONE HALF (or 120) from the center Neutral out to either end.

6) You don't fry RV 120 VAC devices with 240 because they are connected to L1 orrrrrrrr L2 and Neutral which is only 120. Typically half the RV 120 circuits are fed off L1 and Neutral and the other half L2 and Neutral. The ONLY way to get 240 would be wire something L1 to L2 !!!!!!!!!! 

 YOU ASKED .so in phase or out of phase..... if in phase is 220.....right?

 NOOOO if both are in phase its ZERO VOLTS L1 to L2

You get 240 L1 to L2 because both are 180 OUT OF PHASE with each other. When one is 120 + other is 120 - so its 240 L1 to L2

Typical RV loads are connected to L1 and Neutral which is only 120 VAC or L2 and Neutral which is also 120 NOT 240

YOU ASKED .how do i get 2-50 amp legs from breaker panel without being 220?

The Breaker panel has two buss terminals, one wired to L1 other to L2. A typical 15 or 20 Amp 120 Volt Single Pole Circuit Breaker (feeds 120 VAC RV appliances) is wired to ONLY one buss, L1 orrrrrrrrrrr L2. The RV load is also connected to Neutral so it sees 120 VAC. If an appliance like a dryer or heat pump etc required 240, it would be connected to a TWO POLE 240 VOLT BREAKER connected to L1 & L2 so it gets 240.

DISCLAIMER Im longggggggggg retired from Power Distribution Engineering and rusty so no warranty but believe this remains true. If not hopefully the other fine electrical minded gents and electricians or engineers  can add to or correct this 

Got it any questions?? Hope this helps

 

 John T   Live in the RV from Las Vegas Bay dry campground Lake Mead Henderson Nevada headed to Death Valley later.

[Kirk W]

Adding to what John was telling you, the red wire represents conductor L1 and the black is L2 with the center wire what we call neutral. As you can see this figure shows 2 different 120V outlets, one supplied by L1 and neutral, the other supplied by L2 and neutral and the top is labeled 240V but is actually a 120/240V outlet as it can supply either voltage, depending on how the loads are connected. Your RV power cord connects to another distribution panel where L1 & L2 are then separated into two different busses for distribution as 120V to the outlets and appliances of the RV.

 

 

[GlennWest]

I tried to keep it simple guys. 

[Kirk W]

6 minutes ago, GlennWest said:

I tried to keep it simple guys. 

If one can't understand the two pictures then there is great risk in doing their own wiring. You can destroy the electrical systems if you apply 240V where 120V should be. People get electrocuted by making mistakes every year. 

Edited October 30, 2021 by Kirk W

[oldjohnt]

4 hours ago, Kirk W said:

You can destroy the electrical systems if you apply 240V where 120V should be.

AMEN a few years back a good friend Al of Florida (now deceased) was at an RV park and plugged his 50 Amp RV into a recently INCORRECTLY re wired power pedestal THINGS SMOKED AND BURNED AND POPPED AND CRACKED INSTANTLY. Most all things electrical in his nice Class A were fried. The park owner did stand the cost of repairs but his system was never the same and the smell and lots of burned charred areas remained. Not sure if his widow ever got rid of it since???

NICE PICTURE KIRK A pictures worth a thousand words INDEED. In addition it CORRECTLY indicates in an RV "Sub" Panel UNLIKE a homes first main panel, the Neutral Buss and Equipment Ground Buss are insulated and isolated from each other GOOD FIND.....In the case of an RV the universal GROUND SYMBOL becomes similar to a "Substitute Grounding Electrode" by its connection to the RV's Iron Frame. This is to provide a low resistance current return path for any Ground Faults such that the breaker will trip and clear the fault should a live hot wire come in contact with the skin or frame. I'm saving those pics for my files and future reference THANKS

 

4 hours ago, Kirk W said:

People get electrocuted by making mistakes every year. 

 One reason for NEC changes is  when there's a fire or an electrocution in hopes to prevent it from happening again 

John T Still loves electrical chat lol 

  

Edited October 31, 2021 by oldjohnt

[GlennWest]

16 minutes ago, Kirk W said:

If one can't understand the two pictures then there is great risk in doing their own wiring. You can destroy the electrical systems if you apply 240V where 120V should be. People get electrocuted by making mistakes every year. 

Still think ya'll went into detail enough to confuse one. They said nothing about wiring themselfs. Just puluging in and burning up camper. 

[Kirk W]

5 minutes ago, GlennWest said:

They said nothing about wiring themselfs.

3 hours ago, LRKDRV7.3 said:

how do i get 2-50 amp legs from breaker panel without being 220?

We both were trying to answer his question. Why does that bother you so much?  ☺️

Edited October 30, 2021 by Kirk W

[LRKDRV7.3]

Thanks to all,  oldjohnt broke it all down. I have installed multiple barn / shed electrical panels but have been warned "NOT TO WIRE IT 220 OR YOU WILL FRY YOUR RV"

I have pretty much read before what oldjohnt said about opposite legs

L 1& L2 being + & - and not being  "? In phase?" to be 220 in the rv wiring

I use a plug in power checker for rv parks but before i install a 50 amp rv plug at home for my rv well I am real anal about checking 50 times with 50 sources that i understand it correct and can weed out the bull advisors

Thanks again for all of your time, experience and information 

[LRKDRV7.3]

Again many thanks, i reread and copy and pasted oldjohnt step by step breakdown, plus the diagram and breakdowns from glen and ken

i feel comfortable adding the rv plug box now.

Moved into a newer house this summer and well digger pulled out all wiring to rear garage so i had to install new panel this summer. So now i can add the 50 rv plug i've had sitting on shelf for a year

[Kirk W]

8 hours ago, LRKDRV7.3 said:

i feel comfortable adding the rv plug box now.

People like John & I refer to the plug on your RV and the outlet it connects to as a 120/240V plug since you can actually get either from it, depending on how the load is connected. In industrial use there are true 240V lines when measured between a single lead and neutral, but not in home use. I think that most of the horror stories about excessive voltage applied to an RV come from the similarity in look of the typical 30A/120v plug found commonly on RVs(top) to the 30A/240v plugs that are sometimes found on dryers, welders, and such.(bottom) Over the years there has been much confusion between the two but the 3 prong, 30a/240v plugs are pretty much going away. They have both L1 and L2 with ground but no neutral wire.

[GlennWest]

14 hours ago, Kirk W said:

We both were trying to answer his question. Why does that bother you so much?  ☺️

I have read and reread the OP question. I can't get they wanted to wire a box for their camper. I see that now by the last post. I thought they were concerned hooking up at rv parks and frying everything.

[ms60ocb]

17 hours ago, oldjohnt said:

1) A 50 Amp RV has two UnGrounded legs L1 & L2 each of which is 120 VAC with respect to the Grounded Common Conductor Neutral.........

2) Such an RV Park electrical service if wired as most (but not all) are is referred to in the trade as 120/240 Single Phase Three Wire.

3) If such is indeed the case and is typically how most homes are served, L1 & L2 are 180 out of phase with each other (when one is 120+ other is 120-) THEREFORE its 240 VAC L1 to L2.

4) Soooooo you see there is 240 VAC in that 50 Amp RV electrical panel if you measure across L1 to L2 BUT ONLY 120 (1/2 that) from EITHER L1 orrrrrrrrrrrrrrrr L2 to the Common Neutral 

 

oldjohn does a good job. For your 50 Amp service, my quick to verify my service is;

L1 to Neutral 120 V.  L2 to Neutral 120V. L1 to L2 240 V. IF L1 to L2 IS ZERO you have a problem, your neutral wire will be undersized. Under the L1 to L2 240 condition you could have to to 50 amps in Neutral wire but with L1 to L2 measuring Zero you could up 100 amps in the Neutral.

Kirk's Diagram is what your Garage circuit should be looking back into your utility source.

Be Safe, Stay Healthy and don't get in over your head.

Clay

[oldjohnt]

32 minutes ago, ms60ocb said:

oldjohn does a good job. For your 50 Amp service, my quick to verify my service is;

L1 to Neutral 120 V.  L2 to Neutral 120V. L1 to L2 240 V. IF L1 to L2 IS ZERO you have a problem, your neutral wire will be undersized. Under the L1 to L2 240 condition you could have to to 50 amps in Neutral wire but with L1 to L2 measuring Zero you could up 100 amps in the Neutral.

WOW you show an understanding about something many have no clue about CONGRATULATIONS...There are few that understand the problem overloading a Neutral if both L1 & L2 were in phase. If out of phase L1 & L2 Neutral currents cancel out but if not they add IE as you say there would be 100 Neutral Amps in wire only rated for 50 !!!!!!!!

Between my verbal description and Kirks great pictures I think YOU GOT IT !!!!!!!!!!!!!

2 hours ago, Kirk W said:

I think that most of the horror stories about excessive voltage applied to an RV come from the similarity in look of the typical 30A/120v plug found commonly on RVs(top) to the 30A/240v plugs that are sometimes found on dryers, welders, and such.(bottom) Over the years there has been much confusion between the two but the 3 prong, 30a/240v plugs are pretty much going away. They have both L1 and L2 with ground but no neutral wire.

 Another reason those plugs are "pretty much going away" is later model appliances that use BOTH 120 as well as 240 use a 3 Pole 4 Wire Grounding (4 terminal) receptacle and plug which PROPERLY has a dedicated Grounded Conductor Neutral for normal return current VERSUS passing it through the Safety Equipment GroundING Conductor as sometimes done in years past  NOT SAFE

  THANKS FOR THE KIND WORDS glad Kirk and I may have helped

John T  Headed to Red Rocks West of Las Vegas today

 

[LRKDRV7.3]

Always Before i throw the switch on my electrical work i text photos and then call my brother in law a licensed electrician

He is doing my whole house generator in december to be sure all parties concerned are safe 

[Ray,IN]

There is no difference between a 4-prong 50A electric dryer receptacle and a 4-prong 50A RV Receptacle wiring.

The RV difference is found the RV main breaker panel design, it will not allow installation of a 240V breaker. Total electric MH's have a main breaker panel that DOES allow 240V breakers; some come wired for a 240V electric dryer and electric cooktop.

reference: https://www.myrv.us/electric/

[oldjohnt]

1 hour ago, Ray,IN said:

There is no difference between a 4-prong 50A electric dryer receptacle and a 4-prong 50A RV Receptacle wiring.

EXACTLY A NEMA 14-50 R  3 Pole 4 Wire Grounding Receptacle issssssssss a NEMA 14-50R  Receptacle REGARDLESS what tool or appliance or RV it feeds...........ALSO the RV Panel, unlike a homes main service entrance panel, has separate insulated and isolated Neutral and Ground Busses since its in reality A SUB PANEL and the RV frame is bonded to the Ground Buss..

 Nuff said lol

John T  Live from Red Rocks dry camped in the campground West of Las Vegas Nevada with BOTH my Verizon MiFi Jetpack Hotspot and my AT&T ZTE Mobley up n running to get You Tube TV via ROKU and Internet yayyyyyyyyy  

[Kirk W]

1 hour ago, Ray,IN said:

There is no difference between a 4-prong 50A electric dryer receptacle and a 4-prong 50A RV Receptacle wiring.

Very true and in most current dryers there are some parts of it that use 120V power. At least some models have the heating elements split into two matching, 120V elements and the one we had previously also used 120V for the timer and a separate 120v circuit for the lighting of the display and interior. 

On the RV distribution panels, many of them are just as you say, but in the highest priced class A market there are some 240V appliances. I doubt many of us will need to worry about those but they do not even have propane on board. 

[oldjohnt]

NOTE ONE MORE THING  while its indeed true a NEMA 14-50R 3 Pole 4 Wire 50 Amp Grounding Receptacle is the same regardless if for plugging a 50 Amp RV or some other tool/appliance that requires 50 Amp service, some household electric clothes dryers use a NEMA 14-30 R 30 Amp 3 Pole 4 Wire Grounding Receptacles as they often DO NOT require 50 Amps of service, but only 30.  Still such an outlet provides BOTH 120 (used for some circuits as Kirk noted above) as well as 240 Volts, just a bit less amperage and typically wired with 10 Gauge wire. Its more often an electric range that requires 50 instead of only 30 Amps........

Laundry Room

The electrical needs of a laundry room will vary, depending on if the clothes dryer is electric or gas.

• A laundry room needs at least one 20-amp circuit for receptacles serving laundry equipment; this circuit can supply a clothes washer or a gas dryer.
• An electric dryer needs its own 30-amp, 240-volt circuit wired with four conductors (older circuits often have three conductors).
• All receptacles must be GFCI-protected.

Taken from :Common Electrical Code Requirements Room-by-Room (thespruce.com)    

Ive also seen and heard of RV's that used 240 VAC for say clothes dryers or heat pumps etc but I agree there aren't all that many around. To make things worse Ive been at RV parks that used 208Y 120 Volt 3 Phase 4 Wire distribution which is fine for the 120 circuits but there's only 208 not 240 available ????   

We pretty well beat this to death by now lol

John T

[rvhometown123]

There are steps to install a 50A RV plug. Step 1 - Turn off the main switch. Step 2 - Make sure you have an available location on your circuit breaker panel. Step 3: Find a place to install an outdoor power outlet. Step 4 - Install the junction box.Step 5 - Pull the wire through the conduit. Step 6: Plug in the outlet. Step 7: Set the switch. Step 8: Turn on the circuit breaker and test it.

[RV_]

There is a new way to avoid the wiring if your dryer is close enough to where the RV will be. Now if you're a "Sparky" this involves no Sparkiness.

When we get our second plug in EV or PHEV it will not be wired as the first on e was. There is a neat looking (I haven't tried it . . . yet) dryer connector that splits it into two outlets. Since the dryer is run for shorter times than EVs charge, this adapter allows you to plug in your RV, and if the dryer is used it automatically stops the EV charge and runs the dryer, then resumes charging the EV or supplying power to the RV.

Although they are marketing to the EV world the same adapter could power an RV too.

https://electrek.co/2020/09/04/neocharge-240v-smart-splitter/

Edited March 8, 2023 by RV_

[shippreck]

On 10/30/2021 at 3:27 PM, LRKDRV7.3 said:

I have a 2009 DRV Elite suite

So a 50 amp rv has 2 50 amp hot leads.......so in phase or out of phase..... if in phase is 220.....right? Every one says 220 will fry rv electrical.....how do i get 2-50 amp legs from breaker panel without being 220?

Actually, The way you stated it is incorrect.  In phase you have 110.  Out of phase, you have 220.  All you need do is connect one leg of the 220 input to both legs of the RV power plug and then use the neutral for both circuits.  Simply isolate the other hot leg.  The problem there is that the neutral now has to be large enough to handle the current in both circuits in phase.   You should really  have two separate neutrals. As it is normally, When they are out of phase, the neutral does not have to be any larger than each of the hot leads. When one is leg is high the other is low and vs versa.  (out of phase) As long as you never connect both hot leads as one circuit, you never have to worry about 220.

[oldjohnt]

11 hours ago, shippreck said:

Actually, The way you stated it is incorrect.  In phase you have 110.  Out of phase, you have 220.  All you need do is connect one leg of the 220 input to both legs of the RV power plug and then use the neutral for both circuits. 

And to add yet even MORE information lol: In true 120 240 Volt Single Phase Three Wire Service L1 and L2 are 180 out of phase with each other, when one is + 120 the other is - 120 so its 240 across the two !!!!!!!!!!!

If you were to use/connect ONLY ONE leg of 120/240 single phase three wire service over onto BOTH hot terminals (L1 & L2) on a NEMA 14-50R Receptacle A VOLT METER ACROSS THE TWO HOT TERMINALS (really the same feed) WOULD READ ZERO VOLTS POTENTIAL DIFFERENCE,,,,,,,A METER ACROSS         EITHER          TO NEUTRAL WOULD READ 120 VOLTS..

If you use a dogbone connector to convert 30 Amp NEMA TT-30 over to a 50 Amp NEMA 14-50 R Receptacle for powering a 50 Amp RV, it simply connects BOTH legs (in the 50 Amp outlet) to the single available leg of 120 VAC available in the 30 Amp receptacle. AS CORRECTLY noted above, in that case the current carried by the Neutral IS THE SUM OF CURRENTS ON BOTH LEGS. Thats UNLIKE a true 120/240 Volt service connected to a 14-50 in which case the Neutral currents (being 180 out of phase) cancel each other IE if 20 on both legs the Neutral current is zero.

 If you have a 50 Amp RV and use an adapter to power it via a 30 Amp receptacle BE AWARE THERES ONLY 30 AVAILABLE AMPS AND A 30 AMP RATED NEUTRAL !!!!!!!!!!!!

 Hope this helps, best wishes

John T Live in the RV at Pioneer Festival in warm n sunny Zolfo Springs Florida

 

[GeorgiaHybrid]

One thing that alway strikes me as confusing is the number of people that refer to the voltages as 110/220 (which was phased out starting in the 1930's) or 115/230 (which was phased out starting in the 1970's). The USA standard has been 120/240 since (I think) the adoption of the 1984 electrical code.

It has been 120v/240v for 50 years and you still hear the older voltages being used.

Edit: Forgot to add, oldjohnt probably remembers DC power distribution back when he was working with Thomas Edison😁😁😁

Edited March 6, 2023 by GeorgiaHybrid