# High Leg Deltas And Welders



## 460 Delta (May 9, 2018)

At our main garage it's fed with a 230 high leg Delta and for the most part it's just fine. 
With that said, the garage manager bought an inverter based Miller mig welder, the kind that automatically senses the input voltage and adjusts to it. It would weld just fine on 120 volts with limited output but would have a fit when connected to 240 volt. The mechanics grumbled about it but didn't really say too much. 
While doing something else, it hit me that the welder outlets were likely on the high leg on one side. A quick test with my Knopp confirmed my suspicions, it was on B and C phase. I moved it on A and B phase, and it was a different machine altogether. 
The other machines were older machines that were all transformer based that didn't care about a phase to ground voltage reference.
My best guess is that the volt sense was conflicted by the 120 and 208 to ground that was there at the same time.
Moral here is if you put an outlet in for a welding machine, and it's a high leg, you'd best put it on the lighter transformer.


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## gpop (May 14, 2018)

Interesting especially when you consider there are 2 wires and a ground. Maybe some type of filtering that is using the ground to prevent noise.


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## Forge Boyz (Nov 7, 2014)

There is a welding shop we work at with a high leg service that we often intentionally use the high leg for welder receptacles to save panel space. They use inverter based welders there, but I don't know that we have ever had an issue with it 

Sent from my SM-G970U using Tapatalk


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## LGLS (Nov 10, 2007)

WTF ARE all these BS high legs still doing out there?!?!?!


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## SWDweller (Dec 9, 2020)

I did electrical maintenance on an old building where they were building some of the first removalable disk drives for main frame computers. The disks were 12" in diameter with a 4 inch hole. About 1 meg of memory in the beginning. The owner had gone around and bought several pieces of propetry and removed the inner fences so we had 208v 3 phase, 240v 3 phase in the same building. My partner and I did all of the work and he grumbled a lot, I was happy for the pay check. Needed a new panel installed and I asked what was the loads, Small mostly 120v stuff. Got the panel in and pulled the wire, I made up the panel and my partner made up the other end turned on the breaker and being in a hurry I did not check ALL of the relationships in the panel. Put the cover on, while packing up to leave heard a scream and ran inside to see the sectary for the owner covered in plastic. An A-19 lamp had exploded. I ran for the panel shut everything down and found the problem partner had come off the 240v 3 phase service thinking it was the 208v. Quickly removed all the wiring from the middle phase. Planned for a early Saturday project. We got every thing changed over to the 208v service and replaced the light fixture. Never admitted we had made that mistake to the client. Oh ya the Saturday work was on us. To good of a client to piss off over our mistake.


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## 460 Delta (May 9, 2018)

LGLS said:


> WTF ARE all these BS high legs still doing out there?!?!?!


There’s 49 other states outside of NY there hot rod.


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## micromind (Aug 11, 2007)

Forge Boyz said:


> There is a welding shop we work at with a high leg service that we often intentionally use the high leg for welder receptacles to save panel space. They use inverter based welders there, but I don't know that we have ever had an issue with it
> 
> Sent from my SM-G970U using Tapatalk


I've used the high leg for maybe a dozen electronic welders so far, no issues.

I suspect if the welder has trouble with the high leg, something is not quite right with it. It could be a design issue or maybe it has a hidden problem of some sort.


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## CMP (Oct 30, 2019)

I also have a Miller SMT inverter welder, with auto link input selection, and never had an issue on a wild leg service. But it’s a early model.


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## mburtis (Sep 1, 2018)

Personally I think high legs are pretty ingenious. I know they are frowned on nowadays but I think that's mostly because no one bothers to pay attention and blows stuff up with the high leg. Contractors blew all the lights out of our control room hooking them up on the high leg.


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## gpop (May 14, 2018)

mburtis said:


> Personally I think high legs are pretty ingenious. I know they are frowned on nowadays but I think that's mostly because no one bothers to pay attention and blows stuff up with the high leg. Contractors blew all the lights out of our control room hooking them up on the high leg.


You don't need a high leg for that. Just ask the idiots who wired the new office transformer and forgot to hook up a N. No high leg but plenty of smoke. 

2 weeks ago we had poco installed a new high leg service for a lift station. High leg was a service drop charge of a few hundred dollars. 3Y was quoted as 38 thousand. 
Learnt something new. If poco pulls the jumper between the large and small transformer it will measure over 1000 volts to ground on the high leg which is kinda freaky.


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## CMP (Oct 30, 2019)

@460 Delta, my machine is 3phase and 1phase, sounds like yours is a single phase model. That may be the difference, with the auto link sensing. My model is not approved for 120V operation. See the attached equipment tags.


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## 460 Delta (May 9, 2018)

CMP said:


> @460 Delta, my machine is 3phase and 1phase, sounds like yours is a single phase model. That may be the difference, with the auto link sensing. My model is not approved for 120V operation. See the attached equipment tags.
> View attachment 167111
> 
> View attachment 167112


Yes the one I had is a single phase model. The wrench benders seemed happy that they now don’t have to fight over the old Millermatic 200 transformer based machine now.
Those old Millermatics were just tanks you couldn’t kill, they just kept moving along.


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## Almost Retired (Sep 14, 2021)

460 Delta said:


> At our main garage it's fed with a 230 high leg Delta and for the most part it's just fine.
> With that said, the garage manager bought an inverter based Miller mig welder, the kind that automatically senses the input voltage and adjusts to it. It would weld just fine on 120 volts with limited output but would have a fit when connected to 240 volt. The mechanics grumbled about it but didn't really say too much.
> While doing something else, it hit me that the welder outlets were likely on the high leg on one side. A quick test with my Knopp confirmed my suspicions, it was on B and C phase. I moved it on A and B phase, and it was a different machine altogether.
> The other machines were older machines that were all transformer based that didn't care about a phase to ground voltage reference.
> ...


i have hooked up newer welders with electronics, etc. where there was a hi leg
my very first consideration was to keep them off the hi leg


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## mburtis (Sep 1, 2018)

It's amazing how complicated we have managed to make such a simple machine as an arc welder. No doubt none of these newer electronical machines are going to be still kicking in 50 or 75 years like the old transformer behemoths. The new miller we got sure lays down a nice bead though.


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## CMP (Oct 30, 2019)

300A MIG, STICK,TIG, AC, DC in a one man portable package, is something you won’t find in a transformer type machine. portable case, to fit through a watertight hatch, with automatic voltage input changeover.

And it’s pretty old already, I bought it used, and have owned it for about twenty years. It has served me well.


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