Breaker size needed

[Farmer Marty]

i thought i would try posting again as everyone was such a good help last time. I ended up going with Lincoln 256 because i found one a really good deal locally. I have been using for a few months without any issues and am loving it, but recently the 50 amp breaker on the panel has been tripping regularly. It is an older breaker and i am sure that it time to replace it. My question is since i am buying a new breaker anyway should i replace with another 50 amp breaker or should i put a 60 amp breaker in. Thanks all.

[MAC702]

What size wire is on the entire circuit, and how long from welder to panel? Copper or aluminum? Is it a dedicated circuit? Commercial or residential setting? What voltage? Is the receptacle dedicated for welder use or is it possible that something else can be plugged into it?

How hot are you running it? At its rated output of 250A, it's drawing less than 52A on a 240V circuit, especially at a welder's usually low duty cycle. Granted, you might be pushing 300A if you are doing the big stuff the machine can do, and then, yeah, it's gonna suck juice during arc-on. Do you have a clampmeter to test the actual draw going through the breaker?

[Lostone]

What size wire is on the entire circuit, and how long from welder to panel? Copper or aluminum? Is it a dedicated circuit? Commercial or residential setting? Is the receptacle dedicated for welder use or is it possible that something else can be plugged into it?

Pretty much what he said.

To to be honest safest bet is to put a 50amp back. That welder only draws 52amps max per the spec sheet. And that's running wide open at 300amps of output. That's a lot and more then likely your nowhere near that kinda output long enough to trip the breaker.

Try a new breaker first. It's always going to be the cheapest thing to do if you don't have something else on the same circuit as MAC702 pointed out.

[MAC702]

...That welder only draws 52amps max per the spec sheet. And that's running wide open at 300amps of output. ...

Well, the 52A draw is at rated output of 250A. Max output is 300A and will have more draw. But drop the numbers a tiny bit if on a true 240V American circuit. Raise significantly if on a 208V leg of a three-phase wye service.

[Lostone]

Well, the 52A draw is at rated output of 250A. Max output is 300A and will have more draw. But drop the numbers a tiny bit if on a true 240V American circuit. Raise significantly if on a 208V leg of a three-phase wye service.

Your right I read the chart wrong.

Its actually 56A @ 208 volts / 52A @ 230 Volts st the rated 250 amps. But the voltage starts dropping fast after 250 amps. The also list a recommended breaker size of 60 amps.

I wonder if there isn't a voltage drop issue?

[Aeronca41]

Really need to know size and type of wire, as well as length, in the circuit to address both safety and voltage drop concerns.

[ryanjones2150]

And if it's a federal pacific panel, change that whole sapsucker out for something that won't burn your shop down. <br />
<br />
Had another house fire just the other day from one of those FPE panels not tripping the breaker when something shorted. Very dangerous those things are.

[Farmer Marty]

Thanks for all replies. Here is more info. Panel is a Siemens. Wire is a 4 guage copper and is new. I just replaced it a year ago. Distance is 10 feet.

[Aeronca41]

Thanks for all replies. Here is more info. Panel is a Siemens. Wire is a 4 guage copper and is new. I just replaced it a year ago. Distance is 10 feet.

I suspect your existing 50 amp breaker is just getting weak, but you are good to go with a 60 amp breaker on that circuit, with capacity to spare. And, with #4 copper at only 10', you should not be having any issues with voltage drop unless it is a subfeed panel whose main feeder is not adequately sized. The welding circuit you describe is rated for 70 amps worst case per NEC table 310.15(B)(16). That table rates for general applications; you have even more of a safety factor under Art. 630, Electric Welders, sections 630.11(A) and 630.12. Since your machine is rated at 250 amps with 60% duty cycle, 52 amp rated draw, you can multiply the 52 amps by .78 to determine conductor ampacity for the machine, giving an even larger safety factor on your #4 wire. And, Ryan reminded us (very appropriately) to be sure it's not a Federal Pacific Electric (FPE) panel (just thinking about those things makes me shudder to think that there are families with kids sleeping in buildings that still have them even after all these years of warnings. Ryan is still putting out fires they are causing). You are good with the Siemens panel. Just be sure all connections are good and tight. You have a good, safe design there.

An aside--It's going to be interesting when the 2017 code comes out; I understand it adds a requirement to use calibrated torque wrenches (and I assume screwdrivers) for all connnections; how does the inspector check for that? Do they have to watch you make all the connections in the building? Or do you just show them you have the tools? Anxious to see how it plays out.

[Lostone]

An aside--It's going to be interesting when the 2017 code comes out; I understand it adds a requirement to use calibrated torque wrenches (and I assume screwdrivers) for all connnections; how does the inspector check for that? Do they have to watch you make all the connections in the building? Or do you just show them you have the tools? Anxious to see how it plays out.

I asked one of the building inspectors at work. He said that they could spot check a few, but that didnt show it they were over tightened.

My thought was they would have to show the tools, but knowing electricians I've worked with in the past, very few would take the time to used it.

[Aeronca41]

I asked one of the building inspectors at work. He said that they could spot check a few, but that didnt show it they were over tightened.

My thought was they would have to show the tools, but knowing electricians I've worked with in the past, very few would take the time to used it.

Thanks. First comment I've heard from an inspector. I can see this getting very interesting based in individual inspectors' personal preferences. And I certainly agree this would require a huge change in the thinking of the electricians I know.

[ryanjones2150]

Someone enterprising feller will invent a test tool and then retire to Florida.

[Aeronca41]

Probably true.

[Lostone]

Someone enterprising feller will invent a test tool and then retire to Florida.

I would like to retire...

[ryanjones2150]

I hear south Florida is dangerous, so maybe somewhere else in the sun shine state?