On Wed, 15 Jun 2005 12:19:15 -0500, stanley baer
wrote:

Thank-you for the detailed information Eric.

I plan to use 1-1/2' conduit and bury a phone line and water line, all
36" deep while I am at it. The writing on the wire is RW90 XLPE 1000V,
which is moisture resistant as far as I can tell from a quick web search.

Does the 2% voltage drop current of 17A mean that I should fuse the
sub-panel for 35A if I use 2 conductors? I was hopeing to get 50A. My
high current loads are the welders which I operate at low duty cycles.
since this is just a hobby shop there is never more than one big machine
working at once.

stan
Stan,
What the voltage drop means is that if you try to draw more than about
17 amps on one wire the voltage will drop more than 2%. Some electric
things don't mind. But others do. Induction motors, e.g. the typical
compressor motor, will draw more current as the voltage drops trying
to speed back up. This extra current draw then lowers the voltage,
which causes the motor to draw more current etc. This is how brown
outs damage some motorized appliances. Your welder may not care if the
voltage drops too much. You gotta book for the welder? It should say
what it will tolerate.
ERS