Extension Cord? Is it safe?

Date 07-28-2004 21:57

I can give you a partial answer. I don't know how many amps your machine draws so I don't know is your 30 amp outlet is enough or not. However, in our shop, we use extension cords as you describe all the time. These are for 480V power and our cords are made up by our electricians and used for many different machines, including welders.
So I would say that as long as your cord is sized properly and made of cable intended for extension cord usage, it should be OK.
Just keep in mind that long cords must be made of larger wire to avoid voltage drop at the machine. Low voltage can easily damage the welder.

Chet Guilford

By jamesrodr (*)

Date 08-02-2004 07:30

Hi Paul,

Your machine millermatic-175 has the following specs
Input Power
Requires 1-Phase Power
230 V, 19.5 A, 60 Hz

Rated Output
130 A at 20 VDC, 30% Duty Cycle
Output Power Range
30 - 175 Amps

It is very clear that the machine requires a maximum of 19.5 amps at full output which is well within your limit of 30 amps. The 50 amp plug is basically for safety but is not a indication of the actual power drawn by the machine. Even if your extension cord and socket is of 30 amps capacity it will do.So you can weld without any worry.

By PaulR Date 08-02-2004 19:00

Thanks for all the replies folks! Here and by email.
Looks like I might just try this using the dryer outlet.
Paul

By PaulR Date 08-03-2004 18:12

Next question (I have all my Jeep buddies arguing):

I want to run 50 feet of cord......19.5 amps.
I have some 12-3 600v wire but I think that's barely enough.
What wire should I run? 10-3? 8-3?
Anyone have their electrical code book handy?

Thanks again, sorry if these are Newbie questions.

By jamesrodr (*)

Date 08-03-2004 20:26

Paul,
contact a electrician. He will be the right person to answer your questions !

By PaulR Date 08-03-2004 20:30

I did just that...thanks. Contacted an electrician friend.
He said 12-3 is good for 20 amps, but with that length I'll get voltage drop, so go at least 10-3....8-3 even better he said.

Hopefully I'll be welding without a house fire. Paul.

By billvanderhoof (****)

Date 08-04-2004 03:34

http://www.epanorama.net/documents/wiring/wire_resistance.html
Here is a page on wire resistance, voltage drops etc.
It says resistance of #12 wire is .00187 ohms/foot.
Times 100 (out and back in a 50 foot cord) =.187
Times19.5 = 3.6465 volts, voltage drop (ohm's law)
Depending on location there can be considerable variation in the voltage of a nominal 110 line ( usually close to 120 volts). Many machines have brownout compensation built in (I don't know about yours). All in all I believe your extension will be fine.
Bill

By hankj

Date 08-04-2004 03:25

The manual for your MM175 states 19.5 amps at 230 volts as the required service. You can certainly use your dryer feed with an extension cord, but another solution may be to consolodate a couple of circuits in your service panel by replacing full-height breakers with half-height breaker to free up space on the bus for a new 230V circuit. If that option isn't available, then make yourself an extension cord from 12/3 SO type cable. I'd try not to exceed 50'. If you have to, go up to 10/3. Feel free to email me direct at hjuska@2xtreme.net if you need more specific help.

hank