Welder Electric Circuit Question

[brande]

I just purchased a Lincoln Power Mig 215. Now I need to run a new circuit to the garage to power it. Distance from circuit panel (200 amp capacity) is 100 feet. I will also make up a 40' +/- extension cord so I can move the welder around a little.

Lincoln's recommendations for the circuit is for a 60 amp fuse or breaker (Super Lag) and 8 AWG for runs over 100' for 75 C Copper wire in Conduit. The Input Ampere Rating on the Nameplate is 41 amps.

Running a voltage drop calculator for: Copper wire, 240 volt, 3% voltage drop, 60 amps, 140' length indicates to use a #4 conductor (good up to 194’ feet; #6 is good for up to 122’ conductor length calculator). For 41 amps the recommendation is #6 (good up to 178’ feet; #8 is good for up to 112’).

Why the difference? It is Friday night so I can not call Lincoln and I wanted to pick up supplies in the AM to get welding. Can any electricians or others in the know explain the difference?

Thanks

Don't overthink this.

A couple of things enter here.

First, size your service without considering the 40 ft extension cord.(we'll get to that later).

Ampacities of SO, SJ and other heavily covered cable is less than conduit and THHN and similar wire.

Wire ampacity is based on it's ability to stay cool under load.

That said,your situation might be a application for UF (underground feeder) cable.

No conduit needed here.
UF is rated for direct burial in dirt with no conduit.

Keep in mind that the welder companies will err on the safe side (recommending a bit larger wire than what is needed) They also anticipate heavy 8 hr use.

A quick look at UF copper, in direct burial, in the NEC (National Electrical Code) lists an ampacity of 84 for #8.
UF aluminum in this instance allows 66 amps.

Either of these cables will work for your app.

Remember, too that the NEC allows a substantial derate (article 630)for many welding machines as they do not work at absolute full capacity for 8 hours (the protocol for rating most electrical services).

A 40 ft extension of # 8 or # 10 SO, SJ should take care of the rest.
An extension should consider only the distance from the breaker box to the machine. It shoud be assumed that the breaker box was installed correctly and full ampacity is available there.

# 8 or# 10 UF cable should work for you, especially if you are using smaller wire (.030).
.035 may draw a bit more, but should still be ok with the 8 or 10.

Any questions, let me know.

Good Luck

brande

NW Pennsylvania
Welding Technician-25+yr.
Factory Trained
Weld Shop Owner
Welding Consultant
AWS CWI Weld Inspector
bradweld@connecttime.net

 

[Sberry]

You can use ANY plug rated for your application.

Almost, it needs to be a grounding outlet, 3 wire range and dryers are not quite the same as a regular welding outlet.

 

[brande]

Don't overthink this.

A couple of things enter here.

First, size your service without considering the 40 ft extension cord.(we'll get to that later).

Ampacities of SO, SJ and other heavily covered cable is less than conduit and THHN and similar wire.

Wire ampacity is based on it's ability to stay cool under load.

That said,your situation might be a application for UF (underground feeder) cable.

No conduit needed here.
UF is rated for direct burial in dirt with no conduit.

Keep in mind that the welder companies will err on the safe side (recommending a bit larger wire than what is needed) They also anticipate heavy 8 hr use.

A quick look at UF copper, in direct burial, in the NEC (National Electrical Code) lists an ampacity of 84 for #8.
UF aluminum in this instance allows 66 amps.

Either of these cables will work for your app.

Remember, too that the NEC allows a substantial derate (article 630)for many welding machines as they do not work at absolute full capacity for 8 hours (the protocol for rating most electrical services).

A 40 ft extension of # 8 or # 10 SO, SJ should take care of the rest.
An extension should consider only the distance from the breaker box to the machine. It shoud be assumed that the breaker box was installed correctly and full ampacity is available there.

# 8 or# 10 UF cable should work for you, especially if you are using smaller wire (.030).
.035 may draw a bit more, but should still be ok with the 8 or 10.

Any questions, let me know.

Good Luck

brande

NW Pennsylvania