Wiring welders

Sberry

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There needs to be a continuous thread on this. A lot of misunderstanding. This is a start. Seems to be confusion on cord sizing. Basically all 240V machines come cord and plug come 6-50. They need to be designed to be able to safely plug in to a common 50A welder circuit. The 240 only,,, not the dvi9 come 12 cord or better. The owners manuals are very confusing to someone not been schooled on it and the new imports even more so as they dont come with a guide, they seem to leave it to the installer to extrapolate the required wire size.
 

Sberry

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At this point unless there is a specific need we should keep in mind this is for factory supplied cord and plug machines. Its worth noting that the minimum sizes are for single circuit in pipe, for cords and cables its up 1. But almost NONE of them require 6 and certainly not cords and not in home shops. Only machines that even require full wire are 251+ migs. Some have 60% duty and very high outputs but this is special gas, large wires and even non stock guns.
 

Sberry

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Contrary to some belief number 10 can be loaded higher than 30A, actually 60 is the limit, 50 for number 12 and 30 for 14,,,, this is for welders and the allowed over current protection within some equipment. The breaker in these types of circuits DOES NOT protect the building wire for thermal,,, the applied load does. I am going to include minor disclaimers such as most, many etc vs always because there can be some exceptions but they really not relevant to this discussion.
The breaker protecting wire is for general use circuits where there are multiple receptacles where the end user can overload it by plugging in more equipment on the same circuit. The breaker is there for short circuit and machines are designed to be plugged in to a specific current limited circuit. 60,,,, 80 A breakers not allowed for this no matter what the wire size is,,, if it has a 50 plug they need to be on 50 or less.
 
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Sberry

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Now,,,, before we go much farther and I need to resist the urge to say,,, you dont know wtf you talking about,,, I have found,,, I have never been right about what " think" the code should be or some reason they got it wrong and if you are inspired by an original or better idea you are not,,, they already thought about it, already considered it, its not a problem or is and its why they dont ask us to be on the code board.
Also "I did it this way" does NOT mean its correct, often throws other aspects of the code out of compliance and cause it works when you flip the switch doesnt mean its right and simply sizing wire up a couple does not make oit safer and other problems go away. Proper size is different than bigger is always better. While the wire size in the code is "minimum" it does not mean its not adequate, these been in the book a long time, things got a lot better, coatings better, voltage up 10% since they size a lot of wire reducing the current.
Its worth noting that some allow the same wire at 208 as 240, huge difference in current. If its good at 208 way better at higher.
 

PILOON

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If U know the gauge of the welder cord, anything above that should be OK as long as the distance is within reason. (like 30-40 ft and not 100+}
 

Sberry

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The fact that the incoming wire is 1 size larger is the thermal protection for it.
It is a co.mon statement that comes up in most threads that,,,, the breaker is only there to protect the building wire from overheating. This is only true where too many appliances can be plugged in to the same circuit, might be able make that case for a motor ho.e circuit and for service entrance. Most other circuits it's simply a switch that provides short circuit protection for that wire and connected equipment.
 

Sberry

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Its a somewhat difficult concept to grasp that the wire sizing IS the thermal protection and not the breaker.
 

Kardar2

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Springfield ohio
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Snap-on MM250SL
Good subject here, LoL I down loaded a electrical calculator app to figure out the wire size I need. I am running a outlet 44 feet from breaker box. In the app I Iclicked that a I only want 1% on voltage drop so it said I needed #4 AWG. So when I called a electrical supply house. The guy asked me what are you wiring so I told him and he kindly told that it won’t work cause the #4 wire is to stiff and I won’t be Able to get the wire and outlet in the box. So I am going with #6 I saw a guy do it on YouTube. So that’s what I am going to do. Not sure what my voltage drop will be. I will have to re calculate it. Should be in the okay range.
 

Sberry

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There might be instruction sheet with this welder? The electric supply guy is correct, its worth a look in the manual. You would be good at 8 also. The general rule is 5% and you are likely basing this on rated output qhich is rather rare for home/diy/ non outright welding shop production work.
I saw a 250 Snappy a while back come with crappy 12 cord.
But V drop is mostly irrelevant at this level. If it was my dollar would be 8 or possibly 10 if it was single circuit in pipe.
 

Sberry

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I been at this a while. That machine will run dandy from a 10 cable 50 ft long. They list 40 breaker but it should be legal on circuit to 50. Save some jack on the wire and buy another grinder.
 

Sberry

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One of the guys on the Miller forum just got a new multi and said it really flies. He was moving, downsizing and also didnt have to upgrade power for some old monster and selling it for some insane price anyway. It was always somewhat a problem when I was a sprout but we got so much better power and convenience/move circuits, new buildings etc but other than a 300 synch own anything would overheat a 10 wire. Technology is so good, tell me 30 yrs ago would be using a 50$ battery frill all day and I would have said bullshate. They were getting good but heavy and cost 5X as much.
There are other things about cost with these deals but one of the reasons to buy a new modern welder is so you dont got to toss another 300 in wire at it. New modern welders now run from 30A service. I never gave it a lot of thought till they came with it but now we weld at 20A where we used 40.
Lots of reasons to run a wire cost under a dollar a foot vs 4,,,,, if you EVER need a heavy wire face it when it comes, still doesnt make this circuit obsolete.
I would buy 50 ft 10/2 on sale,,, actually probably scrounge some up or buy 250 but ,,, 50 10 mc cable be dandy too. Good for 50A service on these type of welders. Put a 40 on it if you feel better and bet it runs from 30.
 

Sberry

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We got engineers on these forums would be interesting to calculate how long or how many operational hours it would take with that machine at 80% output to save 5$ in power if a guy used a number 6 wire,,,, ha
 

Sberry

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As a side not my neighbor was pricing some scheme the poco was advocating as saving and we calculate would have taken several years, I forget exact now to break even on the wire cost. Would have taken a lifetime at full skilled labor rates on top of that.
 

Sberry

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I near bet a single circuit in pipe and that is a number 12 wire machine. If you use cable use 1 size bigger.
 

welding seabee

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Most of the old transformer type welders came with a 30A 240V short cord. They were not designed to be used for production work so worked fine on the 30A circuit. Guys like me changed them out to 50A for running longer distances and more production type work. I have had the 30A cords get pretty warm at max output. #6 wire/cable is adequate for 50A service and #10 for 30A. If your work keeps tripping a 30A breaker time to move up to 50A. That is NEC compliant wire sizes. Never use wire/cable whose ampacity, by NEC tables, is less than the circuit Ampacity.

Ron
 
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