On Mon, 22 May 2006 10:45:17 -0500, zxcvbob wrote:
Ignoramus18798 wrote:
On Mon, 22 May 2006 13:51:25 GMT, Toller wrote:
"Ignoramus18798" wrote in message
...
I presently have a 220V subpanel in my garage, the circuit is wired
with 6 gauge wire on a 60A circuit breaker.

This circuit is inside a 3/4" conduit. It is comprised of three 6
gauge wires (two hots and neutral, with conduit being the ground).

I now realize that choosing that low capacity was a mistake. (with a
big welder now in the picture) I would like to know just what would be
involved if I wanted to upgrade to 100A.

Can I be able to squeeze, say, two 4 gauge conductors (hots), plus one
8 gauge conductor (neutral), into a 3/4" conduit? Or will I have to
replace the conduit too?

I am very regretful of not doing the right thing and going for max
capacity. When I did it, the only 220V tool I had was a 3 HP
vertical compressor.

Can't answer your question (at least not without looking it up...) but
wonder if you have the electrical capacity in your panel for a 100a sub.

Good question.

I have a 200A panel. The big loads that I may have is a 28A air
conditioner and a 50A kitchen range.

The garage circuit is used for my hobby stuff (compressor, welder),
and, as such, is used very intermittently. As you can guess, the
welder is also going to be used at a low duty cycle, it is not a
production style situation.

That's some data for me to ponder.

i



I think the 60A you have is probably enough. Put the welder on a 50A
circuit; you can use 10 gauge wire as long as it's dedicated to the
welder (special exemption in the code for low-duty-cycle welders.)

Mine is actually 100% duty cycle at 200 amps, although I will never
run it anywhere close to 100% of duty cycle for any meaningful period
of time. With stick welding, the longest run time would for one stick,
perhaps 1-2 minutes, then I would need to change the electrode.

With TIG, it should likely be even less.

You will seldom run the welder at its maximum current setting. On the
rare occasions that you do, turn off the air compressor -- IIRC from the
pictures you posted, it has a *big* tank you can charge up first if you
need compressed air and the welder at the same time.

Yes, you are right 100%, I would definitely turn off the compressor if
I had to do big welding. You are also right that high amperages are
rarely necessary. With steel, I never had a need to go above about 150
amps, not that I have a great deal of experience. I never welded
aluminum, but people say that I need higher amoerages for that.

Anyway, do you know what NEC article 630 says about welder circuit
derating? I googled for a while and saw some references to that
article, but no actual tables.

Thanks!


i