3 prong 50 amp plug to 4 prong 50 amp ????
We lost a good camping friend last night to a sudden heart attack and will be going up to their place to help out with the family/wake/funeral. He has a 3 prong 50 amp outlet on side of garage which ...
Forum Discussion
I realize this is old, and I'm not licensed, but I wanted to clarify what y'all are saying. The point most people miss is the word "branch". I have a 3 prong 50 amp welder circuit in my garage. I installed it, and I know that it goes directly from the outlet to the panel. I can add an adapter to that to connect to an RV with no problem. If I had not installed it, I may not be able to use it, and here's why.
Under normal circumstances, the complete circuit is between the two hot wires, and there is no current on my ground wire. In the event of a short, the current takes the ground wire and goes right to the breaker. But, if I had another appliance on this "branch" that was also connected to that ground wire, the current would go there first. If you happened to be touching something on that appliance that made you the path of least resistance, you would get shocked.
Expand this to the 4 wire; the neutral is always carrying the 120v half of the current. It can't ever be connected to a ground on another appliance because it risks someone else being the path of least resistance. As you say, it is connected to ground at the breaker box, but there's no chance in a properly installed system of anything further out on that ground wire being less resistance than the directly connected ground rod in the panel. So if the current manages to make it all the way back to the breaker box, it won't travel back up to an appliance and energize it. So if anything else shares that "branch", they share ground wires, which won't normally carry current, and they share neutrals and hots, which are expected to carry current. All of the appliances and such are designed to isolate you from the wires expected to carry current, but not from the ones that aren't expected to.
So, back to my garage circuit, I can use it (provided my ground wire is big enough, which I don't recall for certain) because I know that the ground wire is NOT shared by anything else on the branch. But if you have a connection in your garage that you didn't install, it MAY be connected to ground on something else, and could be a danger if you adapt it to 4 prong for the RV.
Under normal circumstances, the complete circuit is between the two hot wires, and there is no current on my ground wire. In the event of a short, the current takes the ground wire and goes right to the breaker. But, if I had another appliance on this "branch" that was also connected to that ground wire, the current would go there first. If you happened to be touching something on that appliance that made you the path of least resistance, you would get shocked.
Expand this to the 4 wire; the neutral is always carrying the 120v half of the current. It can't ever be connected to a ground on another appliance because it risks someone else being the path of least resistance. As you say, it is connected to ground at the breaker box, but there's no chance in a properly installed system of anything further out on that ground wire being less resistance than the directly connected ground rod in the panel. So if the current manages to make it all the way back to the breaker box, it won't travel back up to an appliance and energize it. So if anything else shares that "branch", they share ground wires, which won't normally carry current, and they share neutrals and hots, which are expected to carry current. All of the appliances and such are designed to isolate you from the wires expected to carry current, but not from the ones that aren't expected to.
So, back to my garage circuit, I can use it (provided my ground wire is big enough, which I don't recall for certain) because I know that the ground wire is NOT shared by anything else on the branch. But if you have a connection in your garage that you didn't install, it MAY be connected to ground on something else, and could be a danger if you adapt it to 4 prong for the RV.
