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NE SD | I am not sure how this works but I thought all rvs had no 240 volt appliances so they just run 2 legs of 120 but no 240 between the 2 legs of 120? Sometimes it would be nice to be able to turn the air conditioner on in the rv while at home and the normal household outlet wont run it. This gets tricky and I do not understand it. My welder outlet is supplied with a 50 amp breaker and has either #8 or #10 wired coming into outlet.
Or do the 50 amp rvs have 240 coming into shore power and its split?
Thanks |
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Wallis, TX | IIRC RV outlets have 50 amps 120V, don't think there is a way to get it to work with your welder plug. Maybe Gerald will chime in and confirm this. |
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Northwest Il. | Never ever I was told. Camper is split wired I was told. I know enough about electricity to stay away. |
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| A welder outlet is still just two legs of 120 so it should work just fine. |
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SW MN | Menards has a large assortment of adaptors. just like a generator, you can do it. Your RV is not 3 phase? |
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SE SD | The R V 50 amp plug has 4 prongs. 2- 120 volt hot, 1 ground and a neutral.
A modern welder plug has 3 prongs. 2- 120 volt hot, and a ground, NO NEUTRAL.
Some older welders had a 3 prong APPLIANCE plug, which had 2- 120 volt hot and a neutral, but NO GROUND.
Clear as mud??
Edited by oldpuller 8/16/2016 17:04
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Cherokee County, Northwest Iowa | Anything that moves at the speed of light, and requires a very expensive microscope to observe, such as electricity, I call a qualified electrician. Bruce. |
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| The 240 volt 50 amp RV is wired just like a house and needs the neutral separate from the safety ground. Connecting the RV neutral to the ground will function BUT is considered unsafe because if there is a short the neutral could burn open, putting 120 volts on the grounds in the RV and probably the frame and skin and plumbing, which can be very unhealthy. 120 volts can be deadly because its most likely to put the heart into ventricular fibrillation with a lifetime of about 4 minutes without a defibrillator. Nigher voltages will do more burn damage but stop the heart and with the shock ended the heart tries to restart, and that's quicker when you fall over. So higher voltage shocks are more survivable than 120 volts.
There could be a RV four wire outlet wired to the welder breaker with separate neutral and safety ground using the same breaker and wires by adding a separate neutral wire that the welder probably isn't using.
I hope its bigger than 10 gauge because 10 is only rated at 30 amps.
Gerald J.
Edited by Gerald J. 8/16/2016 17:18
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East Central Ia | oldpuller - 8/16/2016 15:53
The R V 50 amp plug has 4 prongs. 2- 120 volt hot, 1 ground and a neutral.
A modern welder plug has 3 prongs. 2- 120 volt hot, and a ground, NO NEUTRAL.
Some older welders had a 3 prong APPLIANCE plug, which had 2- 120 volt hot and a neutral, but NO GROUND.
Clear as mud??
Anything that will run 120v will need a neutral. Newer welders and equipment that have digital displays or controllers will sometimes use a four wire connection so they have a neutral.
I wired all my 50amp outlets in my shop this way just in case... Most just use a three wire plug but I pulled all four wires for this reason.
Edited by bleedred 8/16/2016 17:38
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NE SD | Are you saying there is 240 from hot leg to hot leg? I also have a onboard onan generator on this camper/toyhauler and I turned on generator and only get 120 to ground and nothing from leg to leg and I tested this at the breaker panel inside? Unless its split somewhere else before the main breaker panel? |
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Texas | Cliff SEIA - 8/16/2016 16:42
A welder outlet is still just two legs of 120 so it should work just fine.
No it won't. A welder outlet has no neutral which is needed for the 120. The third prong on a welder plug is a ground not a neutral. |
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| Each leg will have 120 to ground, when both legs are used together you get 240 volts but in a single phase system it will never measure 240 volts. |
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SW Iowa | Whether you say the 3rd prong of a 3-prong 240V plug is neutral or ground is kind of splitting hairs... either way it's bonded to the same spot in the breaker box, and carries back any current imbalance between the two hot legs.
Think of the ground of 4-wire 240V wiring as a backup neutral. Neutral and ground should both be hooked to earth ground at the main panel.
If you want to try to make a safer adapter than just wiring the RV ground + neutral together into the neutral of the welder plug, you could run a separate wire for the RV plug ground pin and connect that to a known ground. If you got real serious and wanted to do it "right" I suppose you could drive a ground rod; if this is just occasional / temporary and you have grounded metal box or conduit nearby you could consider running the RV ground pin to that.
Not sure what an electrical inspector or insurance person would say about it, but I've seen adapters for this situation where the ground was split out to a spring clamp (like a jumper cable clamp) that could easily be clamped on the metal conduit feeding a 3-wire outlet to maintain a separate ground path. For this to work obviously requires that the 3-wire outlet is properly wired with box/conduit grounded. |
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EC NE | Crickey, there's some scary responses in this thread.
My advice: Review Gerald J's numerous explanations on this topic (Grn & Wht) over & over & over until it sinks in. :-) |
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| I have always plugged my RV into a regular 110 outlet when getting ready/unloading, for a trip.
Can't run the AC and micro at the same time.
When I was a kid my Aunt/Uncle would come and stay at our farm for 2 weeks or so, always ran a 110 extension cord to their Airstream.
Never a problem.
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S.C. Wisconsin | Yes you probably can, but I would recommend a surge protector I have a separate outlet on my shed with the two 120 volt legs, neutral, and a ground. The ground is grounded separate from the box. I still use a surge protector after my inverter failed. I leave it plugged in all of the time as it float charges and keeps the batteries fully charged.
https://www.amazon.com/gp/slredirect/picassoRedirect.html/ref=pa_sp_... |
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Somerville, Indiana | Yes siree...One of them wires that don't do anything, needs to be plenty big and go plumb to the ground, and a DG ground uninterrupted...Call it what ever you want to, but it needs to be there along with the third wire that doesn't have to be uninterrupted...Afraid I confused even more, but saying any more at my level of schoolin isn't goin to help anyone...Just don't think that fourth wire isn't a necessity, because it is...And I short cut electric and water about as much as anyone until it gets to endangering others. |
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| Someone can correct me if I'm wrong, but I think you can't for the same reason that a range and a dryer have different plugs. |
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Faunsdale, AL | Cliff SEIA - 8/16/2016 17:11
Each leg will have 120 to ground, when both legs are used together you get 240 volts but in a single phase system it will never measure 240 volts.
That is impossible. In a single phase 120/240 system, If the two 120's are not from the same line at the source, they will have 240 between them and will measure 240 line-line. To use the 240 you connect using 2 pole breakers that plug on both lines. To use 120 volts, a single pole breaker is used to connect the branch circuit line and the neutral connects to the neutral bar to complete the circuit.
If the two 120's are paralleled to the same 120 volt lline at the source, they will show 120 to neutral but 0 volts between and cannot be used for anything that connects line -line using 2 pole breakers. |
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southern MN | Yea, some scary replies in here.
Anyone who says the ground and the neutral go to the same place so they can be used the same is just scary deal. It just isn't so.
Would be the same as saying both the hot and cold water lines come from the same main valve, so you can interchange the hot and cold pipes any time you want,.... Ugh.
Paul |
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Faunsdale, AL | Problem with this system of external/supplemental grounding is that there is ALREADY a ground in a 3 prong welder/stove receptacle. The thing you are missing is the neutral.
You can use the ground wire as both a neutral and ground, but as Gerald points out if there are any bad connections in the ground wire back to the main panel, you can be in a situation with dangerous voltage on appliance and camper surfaces that should be connected by the ground wire to the main panel ground bar.
The ground wire really shouldn't carry any current in a normal situation, only in an emergency/failure. Then it makes a good return path for the short circuit so enough current can flow to trip a breaker or blow a fuse. It also keeps voltage on touch surfaces from rising to dangerous levels.
Most major 120/240 volt appliances still have the option to use a 3 wire cord instead of a 4 wire by bonding the neutral to ground at the back of the appliance. This keeps from having to pull new wire and install a 4 wire receptacle to use that new appliance. The camper could do the same, but there is some risk. |
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Faunsdale, AL | That depends on the age/design of the range and dryer.
All that stuff used to use 3 prong plugs, but probably different amperage ratings so different configurations of the 3 pins. Now a days, most major appliances are designed for 4 wire connection, but there still may be differences because of amp ratings between a dryer at 30 amps and a range at 50.
The codes are written/plugs are designed to make it impossible to plug an appliance into a receptacle that cannot safely supply the maximum current it can demand. |
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Texas | Lone Cedar - 8/16/2016 18:53
Whether you say the 3rd prong of a 3-prong 240V plug is neutral or ground is kind of splitting hairs... either way it's bonded to the same spot in the breaker box, and carries back any current imbalance between the two hot legs.
Think of the ground of 4-wire 240V wiring as a backup neutral. Neutral and ground should both be hooked to earth ground at the main panel.
If you want to try to make a safer adapter than just wiring the RV ground + neutral together into the neutral of the welder plug, you could run a separate wire for the RV plug ground pin and connect that to a known ground. If you got real serious and wanted to do it "right" I suppose you could drive a ground rod; if this is just occasional / temporary and you have grounded metal box or conduit nearby you could consider running the RV ground pin to that.
Not sure what an electrical inspector or insurance person would say about it, but I've seen adapters for this situation where the ground was split out to a spring clamp (like a jumper cable clamp) that could easily be clamped on the metal conduit feeding a 3-wire outlet to maintain a separate ground path. For this to work obviously requires that the 3-wire outlet is properly wired with box/conduit grounded.
Neutral and ground are not the same thing. The neutral carries return current and the ground is for a fail safe. Never use a ground wire as a neutral. True they arw bonded in the main panel but they serve very different purposes and must not be interchanged or make contact anywhere except the main panel. For example if you add a sub panel the neutral and ground are to be isolated in it and only bonded at the main panel. Fouling this type of thing up is a good way to get electrocuted. |
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Ohio | 50 amp RV Plugs are wired 240 volt. The 30 amp RV Plugs are 2 separate of 120 volt lines, don't add up to 240 volts.
 (test1RV plug.jpg)
 (240V rv plug.jpg)
Attachments
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 test1RV plug.jpg (66KB - 296 downloads)
240V rv plug.jpg (67KB - 301 downloads)
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| Yes I'm expecting 240 volts leg to leg. I run my home standby generator with 120 volts connecting the two hots together, that way no 240 volt loads can be powered and any of those like the air conditioner would overload my generator. Often air conditioner, electric ovens, electric clothes dryers, and electric water heaters need 240 volts. Like the welder. It certainly is possible to run small AC units with 120 volts, typical of home window units, and here I run my water heater on 120 volts for a simple hook up and lower peak power. The 4000 watt 240 volt elements draw only 1000 watts on 120 volts.
The transfer switch for the generator may being connecting like I do to keep the generator from powering any 240 volt loads that tend to be big loads.
Gerald J. |
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| In a single phase system IT WILL measure 240 volts. In a three phase Y connected system it will measure 208 volts. But with the typical farm three phase delta connected (open or closed) with 240 volts leg to leg and the neutral the center tap of one side you get 120 volts to neutral from two of the three phase conductors and 240 volts between any pair of the three phase conductors but the wild leg will be about 189 volts to neutral.
Gerald J. |
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Tennille, GA | Don't try it. I did and smoked my AC/DC converter. Lucky i didnt mess up anything else. Now I hook mine up to a 20a 110v outlet at my shop using the 50amp to 30 amp to 110 adapters and it runs everything including the air, lights. I have not tried to run the ac and microwave at same time.
Edited by ETu 8/17/2016 21:45
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Can I plug my 50 amp RV into my shop welder outlet?
