Need Help sizing a Welder

[wmeek]

I have a AC/DC Arc Welder. The nameplate amps are 40A @ 240V Single phase with a 60% Duty cycle.
40a x 60% Multiplier of .78 = 31.2 A = #10 thhn conductor.
Conductor #10
OCPD 80A ( 40A x 200 % = 80A)
An if I use a Disconnect what size would I need.
I will have a Breaker in panel an disconnect an receptacle at the welder location

 

[Dennis Alwon]

How is 31.2 amps a #10 wire?

 

[Dennis Alwon]

Never mind

 

[wmeek]

I used table 310-16 75 degree column

 

[Dennis Alwon]

Looks like the disco must be sized to the OCPD

 

[Dennis Alwon]

I used table 310-16 75 degree column

Yes but 240.4 G allows this and I hadn't checked otherwise you could not use #10 at 31.2 amps

 

[Dennis Alwon]

I deleted this question. Is it obvious I never wired a welder....

 

[wmeek]

It appears that I will need a 80A OCPD, #8 THHN Conductors an a 100A Non Fused disconnect

 

[Cow]

It appears that I will need a 80A OCPD, #8 THHN Conductors an a 100A Non Fused disconnect

What happened to the #10's?

 

[Dennis Alwon]

It appears that I will need a 80A OCPD, #8 THHN Conductors an a 100A Non Fused disconnect

Why are you saying that a #8 is required. IMO, 240.4(G) will allow the #10 for a 31.2 amp load-- assuming 75C

 

[ActionDave]

Why are you saying that a #8 is required. IMO, 240.4(G) will allow the #10 for a 31.2 amp load-- assuming 75C

It does IMO2.