basic wiring question

[jcb]

I had my workshop wired by an electrician a while back and had him rough wire an outlet for a welder in the eventuality I would get one. The time has come and the new MM 180 will be here on Monday. The electrician had done everything but install the actual plug and had covered the outlet box with a solid cover and had marred the end of the wires. I went out this AM and bought a welding 250v plug and decided to install it but the plug has room for 3 wires (grd + 2 wires) and the installed wire contains 4 (grnd+3 wires). Which 3 do I use on the plug ? The elctrical box has the red and black wire fastened on the breaker, the groung where all other grounds are and the white is where all other whites are. Is it possible that the electrician only needed a 3 strand wired and only had a 4 strand wire on hand ? Asside from taking a part my dryer outlet to see how this is done can any of you help me out ?

Thanks JC

[triggerman]

Your electrician wired your welder outlet to meet any requirements you might need (assuming he used large enough wire). The black and red wires from the breaker and the green ground are all you need. Just leave the white wire capped and rolled up inside the box. The white wire is the neutral and not used on your new outlet. Good luck and congrats on your new welder.

[84ZMike]

The red and black run from the 220v breaker correct?....the green and white are running from where?....it sounds like the green is grounded on the breaker box........
Mike
Looks like you got your answer...

[jcb]

Thanks Trigerman,

[jcb]

Mike,

Yes, the red and black run from the breaker but the green grnd that both of you speak about isn't green, it's bare copper. It is fastened where all other bare copper wires are fastened inside the electrical box .

[AnotherDano]

Mike,

Yes, the red and black run from the breaker but the green grnd that both of you speak about isn't green, it's bare copper. It is fastened where all other bare copper wires are fastened inside the electrical box .

The bare copper wire is the ground. They are coated with green insulation in some cables and bare in others.

Can you see any writing or stamped numbers on the outer insulation (look in the breaker box)? It is important that the wire size match the amp rating for the breaker. I'm sure the electrician used the correct wire size as this is not an uncommon job, but it's always good to know. You'll be looking for numbers like 10/3, 8/3. Let us know what you find.

[jcb]

the wire is a 10-3 wire 300 v. While we're on the subject, the breaker in the workshop is a double 30 amp. The breaker at the house is also a 30 amp but someone suggested upgradding this to a double 50 or 60 amp once the welder is installed. The wire between both electrical boxes is an outdoor rated 6-3.

Does this sound OK to you ?

[Wacko Welder]

OK if you mean the 50 or 60 amp breakers will be protecting the 6/2 and not the 10/3..... A breakers ONLY function is to protect the wire/conductor.

[84ZMike]

The 30 will be just fine for your MM180......and the wire size is fine as well....

[jcb]

Thanks guys, I installed the plug and it works fine.

I have about 20 ft of exterior grade 10/3 wire. would this be suitable for an extension cord for the mm180 if i conect the right male and female connections to it ?