3 prong 50 amp plug to 4 prong 50 amp ????

msmith1199 wrote:
GlennLever, you obviously know way more about electricity than me, but I do have a question based on the info you have posted. If the circuits are basically the same thing with the neutral and the ground eventually connected to each other, then what is the purpose at all in having two different types of plugs? Basically why is it that dryers and ranges and welders for some reason need a different plug than RV's? Is the four prong plug unique to just RV use, or are there other things that also use the four prong plug?

IVYLOG kind alluded to the reasoning behind four vs three.

Back in the day, and yes I am over 60, all houses had two prong outlets. One was the neutral and the other the hot.

The problem with that is a lot of the hand tools and kitchen appliances "grounded" the case and the case was metal. As the plug could be inserted into the wall outlet, you could end up holding a "hot" case. If you were doing that and touched a ground you could get electrocuted.

They then came up with one prong of the plug being larger than the other which would only let you plug the tool in one way, there by insuring the case was always ground.

They then came up with ground fault, I am not clear on the technology, but it senses if there is a potential difference between ground and neutral, and ground fault circuit breaker trip MUCH faster than a normal circuit breaker.

Why there are three prong stove and drier outlets, I do not know. That there are three prong outlets for running stoves and drier says something, but I am not sure what.

Do not do this if you are uncomfortable with it.

Goggle it and understand how it works.

(I have never seen a ground and neutral wire of different gauges in a modern cable)

Thanks for trying with me Rick! I've actually done my own studying on electricity and I learned enough about to know that I don't like messing with it. I've changed out switches and I'll wire up a ceiling fan, but anything more complex than that and I'll call somebody that knows what they are doing.

msmith1199,

Electricity must travel in a complete circuit. The ground wire SHOULD NOT be part of that circuit. The neutral is part of the circuit. (One of those three wires coming into your home that Ivylog mentions is the neutral, the two hots are the other two. Together, they form a complete circuit for the electricity to travel.) Since the ground wire, under proper conditions, has no electric potential across it, there will be no current through it.

SHOULD there be a fault at the appliance end, the ground wire is there to safely conduct that current to a good ground in the breaker panel so that the errant current DOES NOT flow through the operator. Once current flows through the ground wire, there WILL BE a voltage drop across it (Ohm's Law). That's why any other appliance connected to that ground on that branch is now a hazard, because the ground potential on that branch has been elevated.

Not sure if that helps at all. Hopefully it'll clear things up a bit.

Ivylog wrote:
I guess you could run a neutral wire out of the 4 outlet box and plug it into your standard three prong 120V outlet so the neutral is still separated (until it gets to the circuit breaker) box if this will make things right.

The problem with this is that the neutral in this other circuit is probably 14, possibly 12 gauge and it should be 6 gauge for most 50A circuits. Therefore, you're still dealing with an undersized conductor, but it does at least keep the ground circuit intact.

~Rick

The electrons can tell the difference in a neutral and a ground.:B

I guess I sort of understand that Rick, but if both the neutral and the ground go back and attach to the same place, how could one have electric current in it and the other not have current?

Like GlennLever (I'll bet) we are over 60 and remember when 120V only used two wires and 240V used three. Like him I have an adapter that lets me hook into my brothers 3 wire 240V welder outlet to power my MH. We can lead you to the water but we cannot make you drink. For those that cannot understand that the ground and neutral are one and the same at the circuit breaker box and cannot look outside and see that there are only three wires coming into your house; I guess you could run a neutral wire out of the 4 outlet box and plug it into your standard three prong 120V outlet so the neutral is still separated (until it gets to the circuit breaker) box if this will make things right.
I wonder how much liability insurance this guy has for selling this adapter?

GlennLever,

What you say is correct, and it will work. The danger is two-fold.

First, the ground conductors are not designed to be current carrying and are oftentimes a smaller wire than the current carrying conductors. So you run the risk of overloading that wire and potentially causing overheating/fire.

Second is you raised the ground wire to a non-ground potential between that receptacle you wired and the main breaker box. This applies to every ground in that branch circuit, effectively creating a shock hazard for any appliance which uses the ground on that branch.

Will it work? Yes. But there are very good reasons why it shouldn't be done.


msmith1199, appliances which need 120V AND 240V (such as electric ranges, 50A motorhomes, hot-tubs, etc.) use the 4-wire as they need the neutral conductor to split the 240V potential (into 2 120V lines) and then use this wire as a return to the breaker box for any imbalance of current between the two hots. Appliances which use ONLY 240V (baseboard electric heaters, hot water heaters, welders, etc.) can use a 3-wire circuit as the device current will only travel on the 2 hot wires. For any convention, the GROUND wire should NEVER be used to carry current as part of normal operation.

A 50A RV plug is the exact same as used on a modern electric range, and I believe electric dryers and hot tubs as well. It is NOT unique to RV's.

~Rick

Editted to correct original typo of neutral instead of ground. My apologies.

I think most of you are two wire hook up three wire F- up. The grounding conductor (green or bare wire) and the grounded conductor (white) while both do actually go to the same place, serve different fuctions. If you drop the neutral out of your 50 amp 230 volt RV service you will do major damage to pretty much all you 120 volt equiptment. You can have as much as 208 volts to ground on a 120 volt line by droping the neutral. The welding plug will theorecticaly work, but I wouldnt mess with making an adaptor unless you know what your doing.

GlennLever, you obviously know way more about electricity than me, but I do have a question based on the info you have posted. If the circuits are basically the same thing with the neutral and the ground eventually connected to each other, then what is the purpose at all in having two different types of plugs? Basically why is it that dryers and ranges and welders for some reason need a different plug than RV's? Is the four prong plug unique to just RV use, or are there other things that also use the four prong plug?

I have been using my welding outlet in the garage to power the motor home for over a year.

It is true that the three prong outlet has no neutral, it contains two hot leads and a ground, 110 on one led to the ground and 110 on the other leg to the ground. There is 220 cross the two hot legs.




The four prong plug contains two hot leads, one ground, and one neutral.

It also has 220 potential across the two hot leads.





The different between the two is that the four prong contains the neutral.

What most people forget is the natural and ground are connected together on the same buss bar in the breaker box.



Note in this circuit breaker panel that the white netrual wire and the bare ground wire are connected to the same buss bars.



So if the natural and ground are connected together at the plug it will work just fine. It is not code. Every electrician will tell you not to do it, but it works.

What I did is I went to Home Depot and purchased a drier cord, and a four pin outlet that fits the Motor Home. I wired the plug and wire to the outlet, one outside wire (one leg) to one hot prong, the other outside wire to the other hot prong (other leg)and connected the ground and neutral together.