Wire/Breaker size for a Miller Econotig

[o.c.d.]

Hi,

Sorry to ask such a question, but after looking through posts for a while I thought I would just ask.

I'm gearing up to do a perminent install in my garage on this Econotig. Here's what I would like to do. Place the welder next to a welding table towards the garage door. Here are the specifics:

The main panel is only 150 AMP (in the garage). I have swapped some of the single pole breakers with 2 pole ones to get enough space for a 2 pole common trip (normal 208/220V big one).

I need to run ~ 25-30 foot of wire to the welder plug ( I want to run the wire inside the wall from the top of the breaker box to teh attic and back down to the plug), according to the Miller manual the 230V Econotig can draw 52 amps. I should use minum 6 gauge wire with a normal breaker size of 80 Amps (not time delayed or anything).

Questions:

1. Looking at some of the home improvement stores I think I found a 70 AMP breaker in stock at lowes, 60 AMP both of the stores had. What can I expect using let's say the 60 amp? will it flip? If I get the 80 Amp the price almost doubles. The welder is only rated at 20% up high, 100% ~ 60AMPS, I guess I dont understand if this thing uses more current at lower amp settings or at higher ones. This is because the troubleshooting (service) manual states that the SCR (shunt control) works harder at lower settings.

2. What would you think with ~ 30 foot 6-2 behind the wall feeding this welder?

3. What is the calculation used to determine if the main breaker/box is too small? Mainly the entire box. As I stated the thing is only 150 AMP with 1/0 wire from the electric company. We have 2 AC units (one up and one down), dryer, oven, cooktop, and now a 60 to 80 amp welder curcuit. I think I may be over the on panel size.

Any ideas/input would be great.

tom

[Doolittle]

Just try and not run the dryer and oven and welder at the same time. Your main breaker should save you if you do an overdraw (its what its there for). The 60 amps should be fine if it can only pull 52 amps. If you run it wide open and the breaker trips, go for the 70. I dont see that happening though. You wont hurt anything, specially with 6 gauge only running 30 ft. I run my stuff on 25 ft 6 gauge no prob. What kinda wire is the power cord? just curious.

[MicroZone]

I believe mine is on a 50A breaker and it hasn't popped...even on the high setting. We ran 10gauge wire for it but it was a short run from my breaker box to my welding table, perhaps 4 feet total. Just an FYI of another EconoTIG user. Hope that helps...

[zapster]

Welders draw the most amperage at inital start of the weld..
No matter what the heat setting is..
"Idleing" or at "wide open throttle"


The second you touch the pedal is it..then the amps drop off rapidly..
I found all this out when the Hobart kept tripping a 60 the second I touched my pedal..:realmad:

So with a 100 amp breaker and the proper wires installed (hardwired) ... my problems have ended..:cool:

...zap!

[MicroZone]

Ah, I see. Yes, I remember the frustration that Hobart gave you. :laugh:

[Sandy]

The welder is only rated at 20% up high, 100% ~ 60AMPS, I guess I dont understand if this thing uses more current at lower amp settings or at higher ones. This is because the troubleshooting (service) manual states that the SCR (shunt control) works harder at lower settings.

As a side note, the issue in these cases is the heat build-up in the SCR itself, not necessarily a power input problem.

[o.c.d.]

Here's a update and yet another question.

I got done installing the 60 amp breaker and 6/2 nm-b today, damn I'm sore (it sucks getting lazy). After repairing my minor drywall mistake all looks very nice.. However, I re-read the manual and the specifications for the 230 model says to use 6 gauge with a 8 gauge ground. Here's where I screwed up, I never payed attention to what I bought and installed, I installed 6/2 with a 10 gauge ground, should I be concerned or run a larger second ground?

[MAC702]

No need for concern. The #10 ground meets the National Electric Code, and is what I would do for my own installation.

[o.c.d.]

Thanks MAC702,

I thought it would probably be fine, unless L1 or L2 shorted to ground, in which case the small 10 gauge ground would fry and open, but most likely burn through the insulation and short out the 2-6 gauge L1/L2 lines. Or open the 2 pole breaker as the short happens, it's been many many years since I thought it was fun to short 220 together and I never tried to short one leg to ground to see what would happen, so I don't know if 1 leg to ground would make the 2 pole breaker open the same as a L1/L2 short.

Again thanks for the info and confidence.

o.c.d.

[bruceb]

The short would cause the breaker to pop long before the 10 guage wire would even get slightly warm...you are fine.

[MAC702]

The short would cause the breaker to pop long before the 10 guage wire would even get slightly warm...you are fine.
Agreed. Your 60A electric range (which runs at 100% duty cycle) is protected by a #10 ground in its premisis wiring, in most cases.