Running 220V out to the garage?
 

My knowledge of electricity is limited.

I'm going to buy a GTAW machine that requires 220V @ 80 amps. The main breaker panel is in the house, but I have a sub-panel in the garage.

If I wanted a 220V socket out in the garage that could support the welding machine:

1) Would I have to have a new "line" run out from the main panel?
2) Could the work just be done at the sub-panel?
3) Is this something an electrician would have to see to determine?

I'm hiring an electrician to do the work no matter what, I'm just trying to get a heads up on what the required work will be.

Can you get us a pic of the sub-panel with the cover off? It may be as simple as adding the appropriate breaker to the sub-panel. More than likely you have 220v out there already.

I don't see the 3rd leg (red) for 220v

Here's what my sub-panel looks like. The big breaker in the middle is my 220v circuit.

http://rennlight.com/shop/image/2100302.JPG

You'll likely need bigger conductor than what you have anyway.

Hmm, looks like your 220V breaker is 30 amp. I need 80 amp. I'm guessing I'll have to run a "line" out to the garage.

80amps is a very big draw. First the main panel needs to have the capability to deliver that load, probably a 200amp panel. Second the sub-panel needs to be fed by large enough conductors to provide 80 amps, most likely a 100amp panel. A 4awg wire would meet the welder requirement, but considering you'll run lighting and other items I would run at least a 1awg wire. You'll need four wire to the sub-panel, red and black hots, white neutral, and a ground.
So, bascially you don;t have enough power there to run any kind of welder except maybe the smallest 120v available. Call an electrician.

John

You're going to have to run another service out to the garage if you need 80amps just for the GTAW. Just consider what other circuits you will need out there and your now your around 100 amps just satisfy the power requirements in the garage.

Let's say you have a 100 amp service in your basement fed by the meter. You cannot just add another 100 amp service off the existing box. You have to upgrade the wiring from the meter to a new box, presumably to a new 200 amp box. Then you can run an 80amp circuit from the new service box to your machine. You are responsible for the wiring upgrade from the meter to the new box, not the power company.

Hope that helps a little.

Okay, this is going to be a big freakin' deal. :D

Now I know. Thanks!

Chris, your service right now is set up as single-phase 110V. You'll need to pull a two-phase 220V service cable from your main box to this box. Hopefully, your main service can support this load. It not, you'll need to upgrade your main service box, too. You'll need a 220V breaker for your welder. You'll need a grounding block (see Thom's pic, upper right hand side). Your 110V service ties the neutral (white) wires and grounds together, but that will change with the 220V service. You'll split some of the original 110V loads onto one phase of the 220V service (e.g., black to white, plus a ground), and rest on the other phase (red to white, plus the ground). It's been quite a few years since I mucked with these things, so use my comments with a grain of salt. :)

Wow, you guys are fast typists! :D

Path of least resistance (get it?) is to add a 2nd sub-panel, leaving the existing panel as-is.

That's exactly what I was thinking.

I wouldn't have to modify the existing subpanel, and could have a second subpanel dedicated to 220V. The wall that subpanel is mounted on is interior to the garage and hollow--very easy to add a second subpanel on. I want the 220 socket on that wall anyway.

Thank you everyone.

What on earth are you welding that requires an 80 amp welder?

The GTAW (tig) machine I want (and the only one I can get in town) has a maximum draw of 80 amps. If I bother to buy a tig machine, I want it to do DC and AC (so I can weld stainless and aluminum). It's a serious machine and can weld up to 3/8" mild steel. It will be the last welding machine I ever need to buy.

Before I bought my house, the previous owner had the service upgraded from 100 to 200 amps. The electrician added a second box rather than install an entirely new one. It works real well for me. Lots of space for additional circuits if I need them in the future. The workshop has two independent 110v circuits; one GFI protected for the benches and the other on the opposite wall for the power tools (saw, router, compressor, etc). I do not have a 220 welder.

Technically, yes you can. It's not recommended of course but is legal by NEC standards.

Nonetheless, Legion, can you link some specs on the welder?

Most 80 amp TIG welders are describing their output amperage and not the input amps which are normally around 20-30 amps.

http://www.millerwelds.com/products/tig/syncrowave_200/

Both you guys have 220 sub panels except legion has no 220 breakers and Tom does.

What size is the breaker that feeds the sub panels? That determines what wire size goes into them.

Thats what we did at my house. Ran a nipple directly to the service on the outside of the house (other side of the garage wall) and ran cables to the garage box. Now have all the power that will ever be needed.

We also ran a separate 220v plug off of the box down a foot and put a washer/dryer style 220 plug there. That way you can plug in a air compressor, welder and so on without having to hard wire it to the system.