125 amp fuse?? Could that be right?

[Superduper]

OK, so years ago, I traded a wet grinder, a craftsman battery charger sized 200 welder (garage sale find) and a bosch combo hammer drill/demo chipper for this Miller welder. It's a dialarc 250. About to hit the big 5-0 and I figured I better finally learn how to do some welding and make a few projects before it's too late for me. I should say that this welder is nothing like I expected. The 200amp craftsman was maybe 50 pounds. Never used it but picked it up one day at a can't refuse price. The Miller is the weight of a small engine block. I think it's close to 400 pounds. Anyhow, when the trade offer came in, I asked a professional welder about his opinion and he told me that this model is a great machine and simply can't be compared with the cheapo 200 amp models like the craftsman I traded away. He said something like it welds like butter, whatever that means. I wasn't using the other stuff anyway so it seemed like maybe a good trade for both of us.

So had it all this time and it stares back at me every time I go into the garage but as I don't have a suitable plug, I never did get to use it. I am now thinking of finally installing the necessary outlet to play with this guy. So now the question..........

According to the owner's manual, 8-guage sizing is the minimum for the feeder wires to the outlet, which is fine with me. But the max fuse size of 125 amps? That would exceed my subpanel main breaker. It does say rated input current at rated output (miller dialarc 250) is 80.4 amps, which sounds like a lot based on what I read from other members here using 250amp machines. Apparently this machine can peform at 100% duty cycle at full 250amps. I am confident that I will probably never weld anything more than 3/8", maybe an occassional 1/2" tab or something. And as I have zero skills right now, would probably never weld at anything near the max duty cycle of this machine.

Would a 60 amp breaker be sufficient for what I will likely use this for?

 

[brandoro]

What is the size of the breaker protecting your sub panel?

#8 wire is typically only rated to carry 40 amps and should be protected by a 40 amp breaker. A larger breaker would give you an opportunity to burn down your shop.

#3 wire will carry 100 amps and should be protected by 100 amp breaker.

What size (ampacity) cord end is on the welder?

I have a 225 Lincoln on a 50 amp receptacle (240 volt) and have never tripped the breaker. I don't do a lot of welding and mostly smaller stuff.

 

[Superduper]

Hmm. Sort of confusing. Ok, maybe I'm reading the chart wrong. It does say 8-guage but now I'm thinking they mean the input power cord, with max recommend length of 78 feet. They say input conductor, so that's the power cord, right?

Except....
It also says "the recommendations are for a dedicated branch circuit sized for the rated output and duty cycle of the welding power source." Wait, doesn't branch circuit mean from panel to receptacle?

Then it says.......
"Conductor data specifies conductor size between panel board and equipment...." What? So does that mean 8-guage is OK if hardwire-connected from the panel to the equipment? How about from panel to receptacle?

 

[cowski]

60 amp breaker will get about 150 amps of output.

 

[Steave]

Hmm. Sort of confusing. Ok, maybe I'm reading the chart wrong. It does say 8-guage but now I'm thinking they mean the input power cord, with max recommend length of 78 feet. They say input conductor, so that's the power cord, right?

Except....
It also says "the recommendations are for a dedicated branch circuit sized for the rated output and duty cycle of the welding power source." Wait, doesn't branch circuit mean from panel to receptacle?


A dedicated branch circuit for a welder fall under article 630 of the NEC which indicates you are able to use a larger breaker size even for #8 wire. This IS a dedicated circuit for your welder.

The #8 wire they are refering to is from the panel to an appropriate receptacle. You wouldn't be violating any codes by using a 60 amp breaker as you mentioned and would probably never trip this breaker. If your distance from the panel to the receptacle is greater than recommended you might want to run a larger wire.

Without getting technical this is a common sense recommendation.

BTW this is a great welder. Know of folks that still use them even with all the newer welders out there. I'm not sure what the duty cycle is but its not 100%.

Good luck with it. You'll be breaking things just to get to use it.

 

[Superduper]

I'm not sure what the duty cycle is but its not 100%.

Good luck with it. You'll be breaking things just to get to use it.

Thanks. Not sure if I'll actually break things deliberately just so I can fix them, but it would certainly be nice to get to fix, modify or make things with it. A lot would depend upon how fast, how easily or how frustrating it will be to learn the art. I know some people can't solder and that I can do very well.

Also my mistake on the duty cycle. Looks like the specs say 225A@30% and 175A@50%.

I should also say that along with this welder, I traded an old gateway 42" plasma for a firepower FP260 mig welder (what can I say, I like trading) in a different transaction. I did have to drive about 150 miles round trip to get it though. But that one is rated at 250A max, 200A@60% duty cycle and only requires a 50amp receptacle. Seems puzzling to me that the Dialarc would have such high input power requirements whereas the Firepower with seemingly higher amp/duty-cycle rating has much lower input power requirements. I guess it has to to do with the difference in technology but I always though amps were amps.

 

[rcowan]

Depending on the year of manufacture, it seems that some of these manuals and charts on doors were written by EE's FOR EE's.

Did technology change or did we just get better at writing USERS manuals?

RC

 

[tcartwri]

A Fuse and a Breaker are two different things, and are rated completely differently. You can read for hours on fuse design and still have questions. And that's all I can offer.