In article ,
Tom Veatch wrote:
On 22 Oct 2004 19:05:30 GMT, (Greg) wrote:

I am not surprised at all that you are having problems. #6al is only good for
50a at it's 75c rating. The base 60c rating is 40a. Add the 150' length and you
can expect the line sag.
At 60a you will be dropping 14.5 volts

Yeah, the #6AL was what the builder installed when my house was built. I asked
him to run the wire for a 60 amp drop because I knew that I would eventually
build a separate outbuilding for a workshop.

I am now in the process of adding a 32x48 extension to the original 16x24
outbuilding to serve as an equipment shed for tractors and implements as well as
an increase in shop space. Foundation is poured. Will backfill this weekend and
do the concrete flatwork next week.

As a part of the project, I'm going to bump the electrical service up to 100
amps. Needless to say, the existing 6 ga AL wire won't hack it. I'm thinking 2
ga CU is what I'm going to want. But, I'm going to pick up a copy of Glover's
Pocket Ref and run some calculations before committing to anything.

2 ga. copper is the -smallest- you should consider using.

I tend to go on the basis of "figure out what the requirements are, and go
one size larger", so I'd likely run #1 in that situation. grin

As you know, materials cost for a project like this is trivial, relative to
the labor effort involved -- some 'over engineering' is 'cheap insurance' for
handling expanded future needs.