Welder Branch Circuit

[A/A Fuel GTX]

OK.....Here is my stumper for today....

The maximun overcurrent protection device rating for a #10THHN used for an arc welder branch circuit is...

A. 30a
B. 40a
C. 50a
D. 70a

My thinking is it is 80a based on 630.12 (B). #10 THHN is rated at 40a from 310.16 and I just went to 200% of that. But 80a is not a choice so I guess I'd go for answer D. Any takers?

 

[jtester]

I find the correct answer in your list of options. How did you determine that #10 is good for 40 amps? Did you consider the temperature rating of the OCPD it is attached to?

Jim T

 

[A/A Fuel GTX]

My Bad.....I forgot to use the 75C column. I now see that 70a is the correct choice. Now I'm wondering about motors and 430.22 and 430.52. I assume we apply the 75C column for motor brach circuit ampacity too, right?

 

[mario]

:?: .. where did you get the 200% from ? I'm assumming it has to do with "Duty Cycle" ... forgive my ignorance ...

 

[A/A Fuel GTX]

The 200% came out of 630.12 (B). Nobody in this trade is ignorant.....it is by asking questions we all learn. Believe me, I have way more questions than answers...