Electrical question for Inspector 507, and others.

[GaryM]

I have a 50 amp, 220V outlet in my garage for a future stick welder. Four prong outlet, red, black, white, and ground.

Can I make a pigtail and box with two 110V outlets and feed it from this outlet. Don't need 50A. I wasn't smart enough to spec. 20A 110V outlets in the garage, they all seem to be 15A. My wirefeed welder wants 20A.

Could I get 50A at 110V to feed a friends RV if they came by to stay for a while. I think that would depend on the size of the neutral conductor in the cable, right. Would it handle the 50A return circuit?

Don't need to do both at once either.

Thanks for any advice/information.

[beenthere]

Could feed a 20 amp circuit breaker for the 20A circuit.

Could also break the one leg of the 50A to feed the RV too.

I'd suggest getting an electrician to do it by code. My way may to rinky dink to fit code, but I would get it done.

[GaryM]

No, already have two 50A breakers feeding the red and black wires. Want to get a box and mount two sets of 110V 20A receptacles. Feed one with the black and neutral and the other with the red and neutral. As long as I stay below 50A total load I think I'm OK with the neutral, which would carry 40A in this example. Now if I wanted 50A from the red wire and another 50A from the black wire, the neutral would be carrying 100A, right? That's not good. I think as long as I stay at 50A or lower total load I'm OK.

[beenthere]

Some things about 220V that you don't understand, if I am hearing you correctly. The two 110V legs make up the 220V because they are out of phase. They will work without any common or neutral wire as it doesn't carry any load. But it is in the circuit for protection, as is the ground wire.

Each leg in your present outlet is 110, protected by 50A breaker (black and red). The two together will five you 220V. If you want to hook up an RV for 110 at 50A, just use either the black (or the red) wire along with the neutral (common) and the ground.

For 110v, 20A you will need to feed your source through a 20A breaker to get 20A protection. Again, only one leg from the 50A breaker would be used here. To get 220V protected by 20A breaker, use the two 50A feeds to a new box with 20A breakers, one for each leg.

Does this sound familiar to you? Seems you mis-understood my previous post.

Again, get an electrician to keep it code.

[GaryM]

No, I do understand how the 220V vs. 110V works. I guess I really wanted to be sure that I was OK as long as I didn't pull more than 50A total on the 110V side. Because the neutral is sized for 50A right? Hypotheticaly, if I had two neutrals, I could get 110V and 50A from a red and one neutral, and 110V 50A from the black and other neutral. But as there's only one neutral I'm limited to 50A total load. Doesn't matter if it's 110V or 220V. 110V load requires the neutral while the 220V load would theoreticaly not use the neutral. Unless the device had some circuits that required 110V. Then the neutral comes into play. Like the control circuits on a dryer or stove.

Your mention of 20A breakers would be to protect the cordset going to the 20A 110V device, as well as any downstream 110V wiring, right. The 50A breakers will protect the house wiring down to the 220V 50A receptacle

Now I need to find a box and cover to fit all this in.

[jimbrown]

Reference RV wiring you might want to look at this.

http://users3.ev1.net/~crossstitch/RVWiring/wiring.html

[beenthere]

Jim
Excellent explanation.
Thanks for pitching in.

[beenthere]

Remember that the circuit breaker (20A for the welder) is to protect the welder plugged into a 20A outlet and trip the breaker if something causes an overload. Its not just there to protect the wiring. So you want to add a 20A breaker (ok to feed it from the 50A with heavy wiring) to protect the 20A outlet(s).

The 50A breaker will protect whatever device is plugged into it, up to 50A.

[GaryM]

Thanks, and I bookmarked that web page.

So ideally I need to build an enclosure with a pigtail to plug into my 220V 50A receptacle. Then in the enclosure I need two 20A or maybe 30A breakers and two, or more, 20A or 30A receptacles.

Will I be able to find breakers to wire in the line? Or will I need to find a small subpanel with a bus system?

[beenthere]

It would be the neatest and cleanest to go with a small sub panel, with the breakers inside. If so, a 50A service may be a possibility, and give you the most flexibility. I would look at hardwiring it to your 50A feed, and then just switch it off when using the existing 50A outlet. Or combine everything into one unit (subpanel). A few possibilities to think about, and again, a local electrician to help you plan it for the best system would be good, IMO. Sounds like you could make a good usable system from what you have.