Can you plug a 50 amp RV cord into a 4 prong appliance plug?

[Jeff753]

I don't think you can do this but some guys plugged in a 50 amp extension cord and measured each leg at 120v. Is a 50 amp plug and a 4 prong appliance plug (L shaped neutral) wired the same?


Jeff
2001 Dynasty Regent tag axle
Cummins 350 8.3 ISC

[nothermark]

The short answer is maybe. The RV 50 amp plug is a type of standard appliance plug.

First, AFAIK the L blade 4 wire is 30 Amp, not 50. The 50 is flat blades.

The issue is that there are 3 pin and 4 pin 50 amp plugs and sockets. One does not need a neutral if what they want is 240 VAC and a safety ground. Think welders or big heaters. If one measures between the safety ground and either hot lead they should measure 120 VAC as the safety ground and neutral are tied together but the safety ground is not rated to carry a load.

OTOH if one wants both 120 and 240 VAC then the 2 hot + neutral + safety ground is the setup to use. Motor homes fall into that category. So do systems with high current heaters and separate pumps and/or controls. They have a neutral wire to carry the difference of an unbalanced load distribution plus the safety ground.

[Jeff753]

They plunged a 50 amp RV plug into the 4 prong L shaped neutral plug that is wired to a 50 amp breaker. They tested for power from each hot to neutral and each hot to ground and had power.
It looks like the l shaped neutral is too small for the 50 amp RV neutral but apparently it's not. I wasn't there when they tested it.


Jeff
2001 Dynasty Regent tag axle
Cummins 350 8.3 ISC

[wa8yxm]

The only thing I'd want to know for sure is the size of the NEUTRAL wire on the outlet.. I know that you can feed say a 30 amp outlet with 10ga wire but use 12ga for the safety ground.. No problem as that lead is not supposed to EVER carry current and if it does 1/2 second is a long, long time (the breaker should trip by then). so it never has time to overheat.

But I do not know if the code for 4 prong outlets requires the Neutral be the same size as the hots (I am not an electrician) and if it's not.. Bad things can happen.

[HicksRA]

From this site:
RV Electric




This 50-amp service has 4 wires with two 120-volt HOT feeds. It is a misconception that this 50-amp RV service is something special. This service is a STANDARD 120/240 50-amp 3 pole with 4 prongs used for numerous applications.
From this common service we can draw 120 or 240 volts. Each leg is 50 amps @ 120 volts. 50-amp X 120-volt = 6000 watts. But since there are 2 HOT 120-volt legs at 6000 + 6000 = 12,000 watts to use in the RV or 50-amp X 240-volt = 12,000 watts when used as a 240-volt service. Almost ALL 50-amp wired RV's use both sides of the service separately as 120 volt on each leg. Only a few mostly high-end coaches utilize the 240-volt from this same service.
The 50-amp 3-pole 4-wire service is superior to the 30-amp service because of the total amperage available.
30-amp 120-volt service = 3,600 watts
50-amp 120/240-volt service = 12,000 watts
The half round or U is the ground the one directly below it is the WHITE or neutral and the other two black wires are 180 degrees out of phase with each other are the HOT 120-volt. In reality you have TWO 120 volt split service going into your RV.

[Jeff753]

Originally Posted by wa8yxm

The only thing I'd want to know for sure is the size of the NEUTRAL wire on the outlet.. I know that you can feed say a 30 amp outlet with 10ga wire but use 12ga for the safety ground.. No problem as that lead is not supposed to EVER carry current and if it does 1/2 second is a long, long time (the breaker should trip by then). so it never has time to overheat.

But I do not know if the code for 4 prong outlets requires the Neutral be the same size as the hots (I am not an electrician) and if it's not.. Bad things can happen.

On further review these are NEMA 14-50 RV plug (straight blade neutral 4 prong) and NEMA 14-30 Dryer outlet plugs (L Shaped neutral 4 prong).

I've never plugged into a NEMA 14-30 dryer plug with my NEMA 14-50 Rv plug. If one did would they just get 30 Amps on each leg instead of 50?

Does the straight blade neutral from the NEMA 14-50 fit the L shaped NEMA 14-30 hole?





Jeff
2001 Dynasty Regent tag axle
Cummins 350 8.3 ISC

[Timon]

Originally Posted by HicksRA

From this site:
RV ElectricThis 50-amp service has 4 wires with two 120-volt HOT feeds. It is a misconception that this 50-amp RV service is something special. This service is a STANDARD 120/240 50-amp 3 pole with 4 prongs used for numerous applications.
From this common service we can draw 120 or 240 volts. Each leg is 50 amps @ 120 volts. 50-amp X 120-volt = 6000 watts. But since there are 2 HOT 120-volt legs at 6000 + 6000 = 12,000 watts to use in the RV or 50-amp X 240-volt = 12,000 watts when used as a 240-volt service. Almost ALL 50-amp wired RV's use both sides of the service separately as 120 volt on each leg. Only a few mostly high-end coaches utilize the 240-volt from this same service.
The 50-amp 3-pole 4-wire service is superior to the 30-amp service because of the total amperage available.
30-amp 120-volt service = 3,600 watts
50-amp 120/240-volt service = 12,000 watts
The half round or U is the ground the one directly below it is the WHITE or neutral and the other two black wires are 180 degrees out of phase with each other are the HOT 120-volt. In reality you have TWO 120 volt split service going into your RV.

Correct, 50A service for RVs is nothing more than a NEMA 14–50R R=receptacle. If it's indoors it can just be on the wall but outdoors it needs to be in a weather proof box.

[marcham]

Originally Posted by Jeff753

On further review these are NEMA 14-50 RV plug (straight blade neutral 4 prong) and NEMA 14-30 Dryer outlet plugs (L Shaped neutral 4 prong).

I've never plugged into a NEMA 14-30 dryer plug with my NEMA 14-50 Rv plug. If one did would they just get 30 Amps on each leg instead of 50?

Does the straight blade neutral from the NEMA 14-50 fit the L shaped NEMA 14-30 hole?





Jeff
2001 Dynasty Regent tag axle
Cummins 350 8.3 ISC

Drier is 220v (nema 10-30), your rv has 2 110v legs. Don't do it. No part of your rv is designed for 220v.

[marcham]

Originally Posted by wa8yxm

The only thing I'd want to know for sure is the size of the NEUTRAL wire on the outlet.. I know that you can feed say a 30 amp outlet with 10ga wire but use 12ga for the safety ground.. No problem as that lead is not supposed to EVER carry current and if it does 1/2 second is a long, long time (the breaker should trip by then). so it never has time to overheat.

But I do not know if the code for 4 prong outlets requires the Neutral be the same size as the hots (I am not an electrician) and if it's not.. Bad things can happen.

Yes, in 10/3 wiring, all 4 wires are the same size. Same goes for 10/2. Why would you have a separate undersized ground wire?

[Timon]

Originally Posted by marcham

Drier is 220v (nema 10-30), your rv has 2 110v legs. Don't do it. No part of your rv is designed for 220v.

Not so. If you have a 4 pin NEMA 14-50 it delivers both 120 and 240. 240 across the two hot leads and 120 between each hot and the neutral. When using a 30A dog bone it connects the same 120V to both of the hot legs so your coach gets 120V but no 240V.

Same if your generator is only a 120V gen. Larger generators, usually 10K and above, actually produce 120/240V the same as your house gets. Newer Tiffin Phaetons and Busses do this.

[marcham]

Sorry, but dryers use 220V. You cannot get 110v from a dryer outlet. There is one hot and one neutral, 220V between them.

[Timon]

Originally Posted by marcham

Sorry, but dryers use 220V. You cannot get 110v from a dryer outlet. There is one hot and one neutral, 220V between them.

Not always, 240V only is common but some dryers require the neutral so they will have a NEMA 14-30R installed. In most homes built in the last 30+ years you'll find is wired with 10-3, or better, cable so you'll have the neutral when needed.

[twinboat]

Wow, shore power seems to be the most missunderstood thing that gets posted.

Even when it's explained correctly by many posts, someone else says " NO, NO, NO.

Now we have 220 between hot and neturel. Maybe in a commercial 3 phase power building.

[Dutchstar08]

Originally Posted by marcham

Sorry, but dryers use 220V. You cannot get 110v from a dryer outlet. There is one hot and one neutral, 220V between them.

Dam more very bad information. If you don't know what your talking bout keep quite.
The motor in a dryer is 120 bolt. In older homes they used a 3 wire outlet
and the 120 volt was derived from hot to ground connection.
This type of outlet was changed at lease 20 years ago newer home use a 4 wire outlet for the dryer. Two hots one Neutral and ground.
It's basically the same as a 50 amp range/rv outlet except it's 30 amp and uses and L shaped ground. Yes you can make and adapter to use a 4 wire dryer outlet to power your 50 amp RV. Just make sure it's wired correctly.