On 9 Feb 2006 16:41:51 -0800, "sparty" wrote:

I have a 150amp panel in my home, which is decently full, but probably
has space for about another 70amps worth of breakers, but only about 4
spots left.

I HAD planned on running a 70 amp breaker, and then 4 gauge wire to my
garage to a new breaker panel. That will probably max out my panel in
my house. I've done all of the math, and I'm pretty sure it can handle
that.

One of the reasons I am doing this is to run some 230V tools in my
garage. Now recently, I may have come across the opportunity to get a
used cheap Millermatic 250 Welder, which is going to pull 44-45 amps vs
the original 20 amps, I was going to pull with a smaller Welder. This
welder all by itself would require a 60 or 70 amp breaker. So now, I
would like to run 100 amps to my garage instead.

Because of this, I'm thinking I need to increase my House Panel from
150amps to 200amps. What all is involved in this? Does the electrical
company usually do this for free? I know I will need to buy a bigger
main breaker, will there be anymore cost involved?

Is 4 gauge NM-B still ok for 100 amps, or is it pushing it too much?
Pushing that much through it, does that present a fire risk, or is 4
still enough? That kind of distance should be a 2% or less drop, which
is ok, just curious about heat.

This will be through my Basement Ceiling Joists, then up a Garage
finished wall, then through the Garage Attic, then to a Breaker Panel.
Should be about 70-80 feet.

Thanks, James

Several months ago I got a call from DTE Energy (Southeast Michigan),
wanting to know if they could send someone out to do a "meter audit".
Thier concern, they said, was dogs and safety of the auditor.

Anyway, when the guy got here I followed him out back where, as near
as I could tell, all he did was verify the serial number on the meter.

Getting to the point of all this, I mentioned to him that I was
considering a similar upgrade from 100A to 200A, and I was curious as
to what was involved.

The guy told me that I didn't need to do that, since I already had
200A service, and he showed me on the meter where it was marked as
such. He said that for DTE, a 200A installation is their normal
practice, unless the customer requests more.

Since this is an old house, and an old meter, I'd assumed the service
was only 100A, which matches the breaker box in the house.

So maybe all you need to do is find out what your service will handle
and change the breaker box accordingly.

I don't know where you're located but I can't imagine that DTE is
alone in this practice.