Electricity? Never touch the stuff

[L8173]

I'm hiring an electrician to run a 50 amp line at my daughter's house for my RV. I only need 50amps because I have two A/C units. It's a 30' toy hauler. No W/D hookups. Everything is 110 (I believe). Having a difficult time telling the electrician exactly what I need, since I don't really know myself. My cord is a four post cord. What should he run?? He's saying 220, but I don't want to blow stuff up. ANY info on this basic question would be appreciated. I've just never been able to grasp the concept. Please use small words, lol.

[CA_Traveler]

cougar28 wrote:

RLS7201 wrote:

philh wrote:
Two questions,
1. I've heard of some wiring the same 120V phase to both sides. Wouldn't this drive twice as much current through neutral line?
2. Other than the problem of hooking to a single phase circuit, why wouldn't the AC units be 2 phase? Wouldn't that be much more energy efficient?

What is being discussed(?) here is called split phase. The return path on the neutral line carries an inverted sine wave from L1 & L2. When L1 & L2 carry a balanced load, there is no current flow on the neutral path.
Maybe you can follow this.

Richard

RLS7201 is 100% correct. The neutral only carries the unbalanced load between the two line.

Yes the neutral carries the difference of the 2 loads for a 50A RV pedestal plug. I took the post to mean both hots are connected to L1 or L2 like the cheater cord allows.

[cougar28]

philh wrote:
Two questions,
1. I've heard of some wiring the same 120V phase to both sides. Wouldn't this drive twice as much current through neutral line?

That's what happening when when you plug a rv 50 amp using the dog bone into a rv 30 amp. To over current the neutral in that way you would have to be on a larger service and 120v breaker above 50amp.

[CA_Traveler]

Dutch_12078 wrote:

philh wrote:
Two questions,
1. I've heard of some wiring the same 120V phase to both sides. Wouldn't this drive twice as much current through neutral line?
2. Other than the problem of hooking to a single phase circuit, why wouldn't the AC units be 2 phase? Wouldn't that be much more energy efficient?

Yes, if a single 120 volt service is wired to both L1 and L2, the neutral carries the total load from both hot legs. Assuming a standard 50 amp single breaker though, the total load cannot exceed 50 amps.

Standard residential/RV 120/240 volt service is not "2 phase", it's a single "split-phase" service.

Good answer.

You may have read about using a cheater cord - ie one version has 2 male 30A plugs and a female 50A plug (ie 30/30/50). So yes this device can draw 60A on the 50A neutral. Not excessive but still over current. But what about the 30A neutrals that are now connected/shorted together? The current on the 30A neutrals is now determined by the impedance of each 30A neutral. As a result one 30A neutral could be carrying 50A and the other 10A resulting in significant overload of the one neutral.

The 20/30/50 cheater cord has the same problem.

[cougar28]

RLS7201 wrote:

philh wrote:
Two questions,
1. I've heard of some wiring the same 120V phase to both sides. Wouldn't this drive twice as much current through neutral line?
2. Other than the problem of hooking to a single phase circuit, why wouldn't the AC units be 2 phase? Wouldn't that be much more energy efficient?

What is being discussed(?) here is called split phase. The return path on the neutral line carries an inverted sine wave from L1 & L2. When L1 & L2 carry a balanced load, there is no current flow on the neutral path.
Maybe you can follow this.

Richard

RLS7201 is 100% correct. The neutral only carries the unbalanced load between the two line.

[Spridle]

These work out really well. You can be plugged in with the cover down in the rain.
RV Outlet

[Dutch_12078]

philh wrote:
Two questions,
1. I've heard of some wiring the same 120V phase to both sides. Wouldn't this drive twice as much current through neutral line?
2. Other than the problem of hooking to a single phase circuit, why wouldn't the AC units be 2 phase? Wouldn't that be much more energy efficient?

Yes, if a single 120 volt service is wired to both L1 and L2, the neutral carries the total load from both hot legs. Assuming a standard 50 amp single breaker though, the total load cannot exceed 50 amps.

Standard residential/RV 120/240 volt service is not "2 phase", it's a single "split-phase" service.

[RLS7201]

philh wrote:
Two questions,
1. I've heard of some wiring the same 120V phase to both sides. Wouldn't this drive twice as much current through neutral line?
2. Other than the problem of hooking to a single phase circuit, why wouldn't the AC units be 2 phase? Wouldn't that be much more energy efficient?

What is being discussed(?) here is called split phase. The return path on the neutral line carries an inverted sine wave from L1 & L2. When L1 & L2 carry a balanced load, there is no current flow on the neutral path.
Maybe you can follow this.

Richard

[philh]

Two questions,
1. I've heard of some wiring the same 120V phase to both sides. Wouldn't this drive twice as much current through neutral line?
2. Other than the problem of hooking to a single phase circuit, why wouldn't the AC units be 2 phase? Wouldn't that be much more energy efficient?

[CA_Traveler]

time2roll wrote:
Unbelievable amount of confusion on RV.net

Actually all things electrical generate a lot of confusion on rv.net. IMHO electrical is the most confused and least understood subject of all on rv.net.

And it's the same identical circuit as a 50A hardwired stove that doesn't have a plug.

[time2roll]

MEXICOWANDERER wrote:
A question to the forum respondents...

Is not this receptacle and plug the same as for a stick and brick set up for an electric range that demands 120 vac for stove stuff like lights, fans, clock timers?

Yes exactly the same NEMA 14-50R. Same as you find at the campground, same as you find behind the cabinet to plug in the oven at home. Only one way to wire and connect power to meet code. Very common, nothing special.

Unbelievable amount of confusion on RV.net

[MEXICOWANDERER]

A question to the forum respondents...

Is not this receptacle and plug the same as for a stick and brick set up for an electric range that demands 120 vac for stove stuff like lights, fans, clock timers?

[wa8yxm]

50 amp RV service is kind of like a 50 amp Kitchen stove. The only "Tricky" part is I'd make sure the NEUTRAL is the same gauge as the HOTS. But the odds are if you hand him the outlet. He will install it correctly

NOT SO for 30 amp outlets but 50's they do right.

[Bobbo]

12th Man Fan wrote:
Before you have this done make sure the electrician knows what you need. It is not a normal 220V circut it is two 110V.

There have been several posts with pictures on this issue. If you install the wrong one it can cause severe damage to you rig.

Cough, cough. Literally EVERY 4 wire 240v circuit is made up of two 120v circuits. You only get 240v if you use both hot wires instead of a hot and the neutral.

You are obviously thinking of a 3 wire dryer outlet. That has two hot wires and a ground wire, but no neutral. That is what destroys many 30 amp RV's. An electrician sees the big 30 amp outlet and assumes it is a 240v dryer outlet.

If there are 4 wires to the outlet, you are good.

[Old-Biscuit]

Kinda hard for an 'electrician' to screw up a 50A RV install

Now 30A..........
Need to watch them like a hawk cause that can be 120V OR 240V

[CA_Traveler]

The 50A RV plug is a standard and common household 14-50R plug often used for a stove top or oven. The circuit is 120/240V 4 wire 3 pole 60 Hz 50A.

Yes you have 240V into the RV CB panel. Very very few RVs actually have 240V appliances however.

If the plug will be outside then you need a suitable weather enclosure. Also include a 50A dual CB unless it's close to the house CB panel. This is all very common household wiring and should not be any problems for an electrician.

I recommend you also buy a 50/30 and 30/20 adapters and the common 3 light household tester and a plug in voltmeter. Test every plug before using as they can fail or be miswired. The tester will assure that 3 of the 4 wires on a 50A plug are correct which is a good test. More robust 50A testers are available.

The 30A RV plug is however very unique to RVs and it's to often wired for 240V instead of 120V since it's very similar to the common 3 wire 240V dryer circuit. 240V lets the RV smoke out.