[AT] Wire size for welder?? Help welder people!

[Greg Hass]

John:

At the risk of being arrested by the "correct police", I will give what I 
consider to be a "common sense" approach.
First of all, that amperage rating is only at the very top end of the usage 
scale.  I have a 150-amp wire welder and a 250-amp AC/DC stick welder.  I 
have been running both of them on a no.10 wire since I built the shop 10 
years ago, and have never had a problem with the wires getting warm, 
although I did use a 50-amp breaker (on the advice of a licensed 
electrician) to take care of the sudden amperage jolt when striking an 
arc.  A big thing in my favor, however, is that my biggest run is 25 feet 
from breaker box to welder.  If you are already wired for a welder, I would 
say go ahead and try it because if you are properly fused the worst that 
could happen is that you would trip a breaker or blow a fuse.  I would 
guess that most of the welding jobs you would do would draw less than 30 
amps anyhow.  If you want to be correct, I would go with a no. 6 copper or 
no. 4 aluminum entrance cable or Romex, whichever it's called in your 
area.  (Aluminum must always be one size bigger than copper to carry the 
same amperage.)  No. 8 copper would be sufficient for 45 amps, however in 
our area it is next to impossible to find and costs more than no.6, which 
is why I recommended going with the heavier cable.  Just an opinion.

Greg Hass