wrote in message
...
On Mon, 22 May 2006 13:58:15 GMT, 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


You could possibly squeeze two 4s and an 8 in 3/4" (39% fill) but if
there are many bends you will have trouble getting them in there.
That still only gets you 85 amps that you can "round up" to a 90a
breaker. 310.15(B)(6) does not apply to sub panels.
On the other hand, I wouldn't do anything until I had a problem.. I
ran a pretty big shop with a welder and AC on a 60a.

And that assumes the run is not too long or through a very hot area like an
attic in which case you would need to further derate the ampacity of the
conductor.