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MUDBUG
07-12-2006, 01:49 PM
I have a 100A sub-panel in my garage fed with #6 cable and a 60A breaker in the 200A main panel. I have purchased a 20A breaker and 12/2 romex to run to the Welder recepticle (Millermatic 175). The manual for the welder says that it should have a 25A breaker, up to a 30A. I'm planning on using the 20A breaker for now to see how it does. My question is, do you think a 30A breaker would be OK with 12/2 wire if I need to go with that?
Thanks!

Sandy
07-13-2006, 12:23 AM
I always have some reservations about the 12 awg wire for a 175 class, but doing the math, you are within minimum requirements with the 12 awg. So I guess your good there, and based on breaker allowances for welders you could easily put in a 30 amp if you'd like. Try the 20 for awhile unless you can use it as part of a trade in for an upgrade to the 30.

The only obstacle you'll have left is the plug vs 12awg. Many 6-50 Rs are designed for 10 awg minimum so doubling the 12awg for a reliable, long term, worry free connection can be a small wrestling match. Be sure and give that 110% effort if you will :) There are some of the "build it yourself" mulit-purpose receptacles out there that are listed for smaller wire guages but it's not a shoe in that that's what you've got from where I set. Even those an be a pain to get the smaller wire awg's sucked up to my satisfaction. But that's just me.

With the use of 12awg be sure and label that receptacle as welder only.

Have fun. Good luck with the new toy. :)

MAC702
07-13-2006, 12:52 AM
I second the "welder only" label on the receptacle when you use a breaker that's higher than the wire's rating.

Roy Hodges
07-13-2006, 03:53 AM
Yeah, given half a chance , Murphy's Law will prevail.
I gar-on-tee !

MUDBUG
07-13-2006, 10:23 AM
I have no problem getting 10 awg wire for the welder recepticle. I haven't wired it up yet. Maybe I'll use the 12 awg wire for the compressor drop and get some 10 awg and a 30 amp breaker for the welder.

Sandy
07-14-2006, 01:08 AM
Well you're fine with 12 awg and a 30 amp breaker for that welder. That welder, the MM175, and most other of the GMAW/FCAW welders in the 175 class and down. I'm the one who has the problem with 12awg ;) ..

What happens here is that you use the low duty cycle of any particular welder to come up with a multiplier, then run that up against the continuous duty allowances for a given wire gauge and end up with something that says you needs an 11 amp circuit for a 175 at a high amperage but only at 30% duty cycle. Then the NEC allows for upsizing breakers also for single welders, which would allow for around a 40 amp breaker for that wire for those calcs. But for those calcs only.

The issue I have is that all people see is that big ole 220 50 amp recepticle and get to thinking there is no end to what all they can hang off of it. They forget that the hidden wire has been sized for a specific maximum size and type of machine. The use of at least 10 awg adds a little more fudge factor with little more cost. For instance if a friend brings over a larger stick machine with the same plug, or you decide do upgrade or get a large stick yourself or a small TIG.

Make sense?? :D

Roy Hodges
07-14-2006, 02:04 AM
Sandy, what you've just said underscores my belief. NEVER use a smaller wire than NORMALLY accepted for a breaker in ordinary , non restricted (any kind of use) . If i moved out, any body could plug in anything @100 % duty cycle without a concern. I am only person who ever lived in my house , so i know. I sleep good -not worrying about the wiring . My tig-Miller 250 dial-arc hf is on dedicated 100 amp service with full size wire-1 gauge copper , direct wired -no problems since this was wired . and wires only 5 feet long , from breaker to inside of machine .

MUDBUG
07-14-2006, 07:02 AM
It all makes sense. I ended up with 30A breaker and 10 awg wire. I'll label everything to make it clear what goes there. I'll be welding this weekend! :D

mribeiro
08-01-2006, 07:47 AM
Mudbug - I have the same machine and went 10 awg with a 30 amp breaker. I put two outlets in the garage, one being a 50' run and the 10/30 combo is still fine. You'll be happy with that combo.

backuproller
08-01-2006, 07:38 PM
i don't mean to hijack this forum, but this concerns my itty bitty welding shop. i need to run a double 50amp from the house to the sub-panel in my shop. going to have a sp 170 running and some lights and stuff. how much amp drop am i going to get over the 75 feet from panel to panel. i got 6 ga to run the welder plug out of. my compressor is gas and my spectrum 375 will run on the same circuit as the welder but not a the same time ofcourse. thanks guys.

MAC702
08-01-2006, 08:56 PM
Just to be clear, you are putting a NEW subpanel in the shop, and it currently doesn't have one? Is it a separate building?

You won't get any amp drop, but you will get voltage drop. Use this calculator here: http://www.csgnetwork.com/voltagedropcalc.html

You should get 3.6V

NnF
08-04-2006, 08:15 AM
:cool:

All said but I thought I would put in my 2 cents...

The Manual that came with teh Welder say 25 amp or 30 amp Circuit, why would you go with a 20 amp setup (20 amp breaker/ 12 ga wire) ?

If there is a possibility that you may need to go to a 30 amp breaker, go with the 10 gauge wire.
Run the 20 amp breaker with the 10 gauge wire, that's OK, later the wiring will not have to be changed IF you need the larger breaker.

No matter what the appliance call for in terms of current, if you have a 20 amp breaker you should run 12 ga or larger wire, if you have a 30 amp breaker then the wire should be 10ga or larger wire, no other way man.

Luck, but why do the wiring twice, do it right the first time.

Weekend Mig
08-17-2006, 01:41 PM
It all makes sense. I ended up with 30A breaker and 10 awg wire. I'll label everything to make it clear what goes there. I'll be welding this weekend! :D

Glad to hear you went with the #10 wire for the 30A breaker. The danger of using the smaller #12 wire is that the wire could heat up and fail (burn) before the 30A breaker ever felt the heat and tripped. Electrical Codes in my area do not allow the use of #12 with 30A. #10 is the minimum - - for fire safety's sake.

One question I have though - - is your welder a 110V or 220V. If it's a 110V, where did you find a 110V wall receptacle rated for 30A. I would like to install a plug for my 110V welder on a 30A circuit as well, but the highest rated 110V receptacle I can find is 20A.

Weekend Mig
08-17-2006, 01:45 PM
One question I have though - - is your welder a 110V or 220V. If it's a 110V, where did you find a 110V wall receptacle rated for 30A. I would like to install a plug for my 110V welder on a 30A circuit as well, but the highest rated 110V receptacle I can find is 20A.

Forget I asked that. I just went to Miller's site and saw that it's a 230V. Wall receptacle issue is mute...:) - - - unless someone knows where I can get a 110V / 30A receptacle???

MAC702
08-17-2006, 02:24 PM
...unless someone knows where I can get a 110V / 30A receptacle???
If you need one for some reason, they are common for small RVs, and available at Home Depot.

MAC702
08-17-2006, 02:27 PM
if you have a 20 amp breaker you should run 12 ga or larger wire, if you have a 30 amp breaker then the wire should be 10ga or larger wire, no other way man.

Luck, but why do the wiring twice, do it right the first time.
Unless of course, you are installing a welding machine and desire to size according to the provisions of NEC (National Electric Code) Article 630, which most AHJs (Authorities Having Jurisdiction) abide by.

Just because it's the recommendation, doesn't mean it's the only way, man.

I agree that there is little benefit in this class of installation to use the duty cycle ratings and downsize the wire. But it is incorrect to say that it is not an option.

Weekend Mig
08-17-2006, 02:47 PM
If you need one for some reason, they are common for small RVs, and available at Home Depot.
Is that right? HD stores up here in Canada do not stock a 30A 110V. The highest rated one I can find is 20A. I'll have to look at the RV option. Maybe a local RV dealer has something.

Thanks for the suggestions.

MAC702
08-17-2006, 03:42 PM
I just bought one at my local Home Depot for my RV. If it's not common in Canada, you can no doubt find them on eBay or a real online electrical supply. If you get desperate, I can get one and ship it to you.

Weekend Mig
08-17-2006, 04:09 PM
I just bought one at my local Home Depot for my RV. If it's not common in Canada, you can no doubt find them on eBay or a real online electrical supply. If you get desperate, I can get one and ship it to you.
Does the receptacle have a standard 110V setup (2 straight prongs and a ground)? My welder has just a regular plug - - fairly heavy cord, but regular plug.

Having said all of this, my welder is rated for 20A input, so I'm probably OK with a 20A circuit. I just thought I would apply my typical "go BIG or go home" theory to this issue.:p

MAC702
08-17-2006, 04:32 PM
No, it is a larger plug/receptacle.

If it's rated for a 20A input, the best way to go is a 20A dedicated circuit, with nothing else on it. In this case, #12 wire is plenty unless it is an exceptionally long distance.

Weekend Mig
08-17-2006, 04:55 PM
That's what I thought about the plug...

I think I will stick with 20A and #12 wire. For the amount of welding I actually do, I suspect I will be fine. 'till now, I've only used a 15A circuit, so the 20A will be an improvement.

Thanks again for the info - what a great site. I'm hoping to be around more in the future. Just finishing up a garage/shop build at home and looking forward to spending many hours "playing" with all my tools.

Oh MUDBUG - - sorry for the thread hijacking :)

wannabe_welder
09-01-2006, 08:52 AM
Just as a note of clarification, the Lincoln manual calls for a 40 amp breaker for the 175 welder. I just went through it last night with mine.

MAC702
09-01-2006, 11:35 AM
Lincoln is the worst when it comes to consistency and practicality in the electrical recommendations in their manuals. Miller/Hobart is not good, but not as bad as Lincoln. I've read most of their manuals on many machines.

The 175A-class of MIG machines only need a 30A breaker and #12 wire at a minimum. Feel free to upgrade as you see fit.