What Gauge Extension Cord

[kanoa9321]

I will be getting a Miller 210 soon and will need about a 10-15ft Extension Cord What Gauge wire would you guys recommend? Thanks

[Roy Hodges]

if it's a mig , you need at least 8 gauge . if it's a tig you'd need a 6 gauge . w/the price of copper , now i hope you are RICH. P S , I think everybody better buy what they want soon, before prices skyrocket from where they are now . oil barron$ are out to wipe u$ out .and oil is what will cause all price$ to $kyrocket

[MAC702]

Where are you getting these numbers, Roy? Why are they solely based on process and not input amperage and duty cycle?

If you want to build it yourself, get NEMA 6-50 ends and run #10 SO cord in between. You can take that machine a long way with that wire. #8 would be gravy.

[Roy Hodges]

i just didn't mention duty cycle. lets say i want NO possible problems . you want to take chances , go ahead . I considered that tig needs more amperage (hy-freq ) . but anybody who wants to weld , should really find out for themselves the absolute FACTS, if they don't want problems . NOTHING comes easy , or CHEAP. I was considering input amperage . you HAVE to . Better safe than sorry .

[Sandy]

This is coming from a different direction, but I think you should at least consider a cord a little longer than 10-15 feet. Unless you are confined to a small work area, or don't plan on working on large projects, or don't plan on reaching outside, 10-15 feet is going to leave you wanting. So if you can squeek a little more out of the budget make that cord longer. The costs of the ends is the same whether a cord is 10 or 50 foot.

Like mac says, get the SO type. Get oil and water resistant. It's tough and will take a beating.

[Roy Hodges]

Sandy ; you sure are right about the length of cord , it seems they always need to be longer than one might think. Better ask mac how long they need to be

[MAC702]

:) I like you Roy, really. Last thing I want to do is tick you off.

I just noticed that your recommendations were based on a process.

He mentioned his specific machine, a Miller 210, assumed Millermatic 210, which will draw less than 27A at its rated output of 160A (which is already a 60% duty cycle.) As its output increases to its maximum, its duty cycle drops significantly. #10 wire in a THHN insulation, 2-conductor raceway, is rated for 40A, even when having the required 30A breaker in normal, non-welder usage.

It's not wrong to recommend larger for future expansion, etc. But, I always make sure they know what they NEED first, considering the costs involved. A blanket "you need at least 8 gauge" is oversimplifying and starting too high, in my professional opinion. There is a significant cost increase in #10 SO versus #8 SO, and it's a much bigger PITB to wrap and unwrap, etc.

I also like Sandy's recommendation to make the cord as long as you can feasibly see moving the machine. Maybe a project out in the middle of the driveway, etc?

[halbritt]

I have found that 10/3 SO cable is commonly available at hardware stores relatively inexpensively. I'd hesitate to use 8/3 as much as possible as it's expensive and difficult to find. Assuming the MM210 draws about 30A then one could use a 10AWG cable up to about 250 feet. This assumes a maximum 6% voltage drop. At 15 feet, the voltage drop for 10/3 is ~.4%, or less than one volt. 10/3 would be more than sufficient for this application.

Here's a link to help with these sort of calculations:
http://www.powerstream.com/Wire_Size.htm

Also, I noticed the other day that http://www.weldingsupply.com had a sale on NEMA 6-50 plugs and receptacles.

[kanoa9321]

Thanks for the help guys.

15ft will get my extension cord to any area of the garage plus I still have how ever many feet of cord the actual welder has.

This is for everyday use and practicallity, but if needed I have one already thats long enough to reach from here to China if needed.

Sorry for the ignorance but what does SO mean?

[MAC702]

SO is hard service cord. There are many specific types that I just call SO, but it might be SOW, SOO, SOOW, SEOW, etc, etc.

Article 400 of the National Electric Code outlines all cords and cables and their specifics.

[kanoa9321]

Ok Sounds good thanks guys

[gnm109]

SO is hard service cord. There are many specific types that I just call SO, but it might be SOW, SOO, SOOW, SEOW, etc, etc.

Article 400 of the National Electric Code outlines all cords and cables and their specifics.


I recently priced some 8-3 SOOW here in Sacramento area and they want $2.79 a foot......!

[MAC702]

I recently priced some 8-3 SOOW here in Sacramento area and they want $2.79 a foot......!
For example, in this cord, SO means a thermoset insulation hard service cord. The next O means that it has an oil-resistant insulation. The W means it is suitable for wet locations instead of just damp.

[chicksdigwagons]

It's not wrong to recommend larger for future expansion, etc. But, I always make sure they know what they NEED first, considering the costs involved. A blanket "you need at least 8 gauge" is oversimplifying and starting too high, in my professional opinion. There is a significant cost increase in #10 SO versus #8 SO, and it's a much bigger PITB to wrap and unwrap, etc.

I also like Sandy's recommendation to make the cord as long as you can feasibly see moving the machine. Maybe a project out in the middle of the driveway, etc?

While I do agree with you, you did forget to mention that the length of the cord plays a large role in its wire gauge than the draw of the device. While X cord is rated for X amps, its rated for that at X distance. When you start to increase distance you ultimately need a fatter pipe. While 220 welders are a little more tolerant than 110 units of voltage drop, you'll still see the best performance when you run a cable that is suitable for both your draw and your length. And in my opinion, that'd be one step larger than usually recommended for both expansion and performance.

[MAC702]

I will be getting a Miller 210 soon and will need about a 10-15ft Extension Cord What Gauge wire would you guys recommend? Thanks
I did not mention length because a length that would make a difference would be far longer than the length he already told us or even our ideas to make it longer for reaching outside, etc.

But yes, when significant, you need to know length and check the voltage drop with your expected loads.

[MAC702]

you'll still see the best performance when you run a cable that is suitable for both your draw and your length. And in my opinion, that'd be one step larger than usually recommended for both expansion and performance.
Please clarify that. When you say "usually recommended," who's doing the recommending? So called "electricians?" "Engineers?" random people on the Internet? Counter lacky at the wholesale house? Nonexistant aisle personnel at Home Depot? Weldors?

My professional recommendation was based on the 2005 National Electric Code and years of industrial and residential electrical installations.

I think we would completely agree that an opinion is only as good as the data that back it up.

Actually, it could seem that #8 was the "usual recommendation." So, then, would you recommend #6, based on that? Hey, it would certainly work, but the idea is not to just cover our butts by overkill. There is a legitimate answer based on ampacities and the Code.

Again, I'm not trying to be impolite or talk down to anyone. But I stand by my professional opinion and would point out that some other opinions here have not been based on that data, and this is the OP's money and convenience that could be better spent elsewhere.

[chicksdigwagons]

Usually recommended, would be what is considered adequate by a majority of people with reasonable ability to make those judgments. The current capacity of cables of various sizes is well documented, in code books and otherwise, but also assumes some things. It assumes a certain strand count, a certain quality of copper and manufacturing, and a certain maximum length. This is one reason why, in my opinion, I'd personally recommend stepping one gauge above the common recommendation for a long extension cord. This is only because I have to assume people will buy the cheapest wire they can, rather than spend the coin for a higher quality cable, and it will ensure the least ammount of voltage drop - important with welding. Maybe not so if you're powering a dryer or oven.

I'm not going to assume that the books assume a rating for a low quality not necessarily coded or approved cable. Thats a mouthful.

Furthermore, my personal recommendations also encompasses the future possibility of expansion, equipment malfunction, any other less than ideal conditions that may exist in the near or distant future.

Now, I do understand that my priorities or applications may not be in line with others. For someone bidding an electrical wiring job, yes, code level wiring is all that is likely to be installed. And yes, it will suffice. But, I stand by my recommendation, in regards to an extension cord used for welding duty, to spec it out a notch higher than would be minimally required to safely handle the workload.

*Except possibly in cases where you are getting into some seriously fat wire. For example, going from a 10-3 to an 8-3 is not as major as going from a 6-3 to a 4-3.

[MAC702]

The machine has a 30% duty cycle when maxed out at 210A. At this output, its input will be roughly 35.5A. Article 630 of the National Electric Code means we apply a multiplier of 0.55 to machine's ampacity, for a rated amp draw of 35.5A * 0.55 = 19.5A. Granted, this is not often done in residential installations. I've already demonstrated that a 100% duty cycle is already more than safe, so this just goes to prove the ADDED safety factor of the actual facts, not opinions or guesses or usual observations.

There is plenty of safety BUILT-IN to the National Electric Code, and the common gauges of 14, 12, and 10 are limited to circuit protection (in normal situations) that are already lower than the ampacity of the wire itself.

Opinions are opinions. #10 is already overkill according to the math.

THIS DOES NOT MEAN HE SHOULDN'T LISTEN TO YOUR ADVICE. Y'all make some good points. It allows for future use of other things.

BUT, #10 is all he needs for a much more than safe and more flexible and less expensive installation.

I don't see anyone else using the National Electric Code or the printed Specifications of the Millermatic 210 in their "opinions." The OP needs the facts, and he can make his decision based on them, AND on the ideas from others, no big deal, as long as the facts get in there among the opinions.

[halbritt]

The quality of a given cable has nothing to do with the amount of voltage drop which is entirely dependent on the diameter of the conductors. In higher frequency applications, strand count and "skin effect" can make a difference, but this isn't the case at 60Hz.

[awright]

I'm going to foolishly step into the middle of this exchange to attempt to clarify a couple of issues, hopefully for the benefit of onlookers who may be confused about the technical points involved.

There are two fundamental and somewhat separate issues involved in the selection of wire size for extension cords. They are (1) end-to-end voltage drop and (2) heat dissipation. (Yes, yes, they are directly related because the voltage drop is current times wire resistance and the power dissipated in heat is current squared times wire resistance, but that is not my point.)

The AMPACITY listed in the code for wire of a given size in a given configuration (SO flexible cord, wire in open air, wire in a raceway, etc.) is determined by the heat generated per unit length of wire, the rate at which that heat can escape from the wire due to it's surroundings, and the temperature that the insulation of the wire can tolerate. Thus, the ability of an SO cord to safely carry any specific current is independent of the length of the cord.

The VOLTAGE DROP of the cord from end-to-end for a given current is directly proportional to the length of the cord. That is, it is the voltage drop per foot times the length of the cord in feet. The amount of voltage drop in the extension cord and the resulting voltage applied to the input of the powered appliance may affect the performance of the appliance and the safety of running the appliance at that reduced voltage, but that is a completely separate issue from the ability of the wire to safely carry that current.

If, for example, you are powering an electric heater in a room using an extension cord located entirely within that room, you wouldn't necessarily care what the voltage drop was in the extension cord (provided the cord could safely carry the current) because the heater doesn't care if it receives a slightly low voltage and all the heat you are paying for goes into heating the room, whether it comes off the extension cord or the heater coil. That is, it wouldn't make sense to oversize the extension cord no matter how long it was. Conversely, if you are powering a critical piece of scientific equipment that is very sensitive to it's supply voltage, you might oversize even a short extension cord to minimize the voltage drop even though the ampacity might be much more than you need to safely carry the current.

Note that ampacity adjustments due to the limited duty cycle of the load have nothing whatsoever to do with the permissible voltage drop due to the LENGTH of the extension cord. The voltage drop is an instantaneous phenomenon and if your instrument loses its memory or your bead lacks penetration due to low supply voltage, you care about it at that instant. On the other hand, ampacity adjustments for duty cycle have nothing to do with cable length and everything to do with heat dissipation per foot of cable and the ability of the wire to get rid of that heat AVERAGED OVER TIME.

While I, too, tend to oversize my extension cords where convenient, I have to side with MAC702 on his point that there is no strong reason for kanoa9321to upsize his extension cord from #10. He clearly stated in his first post that he needed a 10-15 foot extension cord. Halbritt correctly points out that the voltage drop for 30 amps through a 15-foot #10 extension cord would be about 1 volt, which is negligible. There would be no noticeable loss of power seen by the operator and heat dissipation in the cord is quite acceptable.

awright

[MAC702]

Excellent explanations, awright.

And when voltage drop is critical, measure it at the receptacle (under load) or else you'll have to know it at the panel and factor in the drop of the supply cabling. Anything overly sensitive would need a UPS anyway to handle the normal PoCo fluctuations.

Again, though, as you agree, voltage drop is not significant to this application.

[chicksdigwagons]

For 10-15ft I would also agree that the voltage drop is negligible. However, I'll add that whenever I needed a 10-15ft cord, I instead opted for a 30 footer and thanked myself times over again for doing so. I'd recommend that in this case. Its better to have it an not need it than need it and not have it.

But I'm sure MAC would rather spec the cord length exactly to whats needed now with no room for expansion ;)

[halbritt]

As I previously stated, with a 30A draw at 240VAC one could use up to 250 feet of 10AWG before the voltage drop exceeded six percent. For that current and voltage, the voltage drop over 30 feet is still negligible.

[MAC702]

But I'm sure MAC would rather spec the cord length exactly to whats needed now with no room for expansion ;)
See post #7.

[chicksdigwagons]

See post #7.

Yeah, I saw that. I was just rustling your feathers MAC :drinkup:

[MAC702]

I rustle easily... :drinkup:

[ZachMN]

I just got a Millermatic 210 and made my own cord; I used 6 gauge as I am planning on getting a tig machine in the future. They had two styles of 6-3 wire
one was much more stiff and not suited as a cord. the other was much nicer and had a kind of 'Ruber" jacket around it.

After reading through some of the responses it would be correct to say in terms of the differences of the two number six cords I was looking at that one had a higher strand cound. When I stripped it they strands were way smaller making it better suited as an extension cord (i.e. more flexible). By the way I made my cord 40 feet which cost me $138.00.

Also a note, the cord that is supplied with the Miller 210 says 12-3 on it.

[MAC702]

I just got a Millermatic 210 and made my own cord; I used 6 gauge as I am planning on getting a tig machine in the future. For what you are doing go to Home Depot and get some 8 Gauge rubberized cord; I say rubberized because when I was looking they had two styles of 6 gauge. One style has like 6 pieces of wire whereas the other has a couple of hundred which makes it easier to move around i.e. its not as stiff.
Since this is your first post and we aren't yet familiar with your experience or qualifications, may I ask why you recommend #8? Is it because you don't know what is needed so are recommending overkill on purpose? Did you read this thread before answering the question? If you recommend overkill, you should say why.

Here we go again... :sleeping:

By "rubberized" I think you mean SOOW cord. It's designed for extension cords and other flexible installations. The other you describe must be standard wiring (19-strand) for permanent installations, like NM or separate conductors in conduit? These are not choices, each is for a specific usage.

[ZachMN]

obviously you cannot read: I said I was planning on getting a tig machine in the future. Also for what its worth it is much safer to err on the big side with wire rather than less.

[MAC702]

obviously you cannot read: I said I was planning on getting a tig machine in the future.
Excuse me? You're getting off to a good start. My reading is excellent, thank you very much. I did not address what you bought for your machine at all.

Here's the quote you made (before you editted your post and removed it; it also appears in my last post: ) "...For what you are doing go to Home Depot and get some 8 Gauge rubberized cord;..."

[MAC702]

All of you should keep in mind that I am NOT TELLING the OP to get #10 wire.

I am telling him that it is PLENTY SUFFICIENT for his stated needs. He is absolutely welcome to upgrade based on other recommendations. But many of those recommendations have made it seem that overkill was NECESSARY, rather than possibly desirable. It's only professional to inform first, and then recommend. I really have nothing against you guys personally... :drinkup:

[MAC702]

They had two styles of 6-3 wire
one was much more stiff and not suited as a cord. the other was much nicer and had a kind of 'Ruber" jacket around it.
Also, a 6/3 "cord" counts the ground; its 6/3 has three wires. The stiffer 6/3 you saw was likely a cable assembly for premesis wiring, like NM. It does NOT count the ground, so its 6/3 would have four wires.

[halbritt]

I am consistently baffled by the desire of some folks on this and other welding forums to recommend extension cords that are way overrated for a given application. The NEC has some excellent guidelines with regard to this topic and should be considered the authoritative source for this sort of information. MAC702, I appreciate your perserverence in maintaining rational discourse on this topic.

[gnm109]

All of you should keep in mind that I am NOT TELLING the OP to get #10 wire.

I am telling him that it is PLENTY SUFFICIENT for his stated needs. He is absolutely welcome to upgrade based on other recommendations. But many of those recommendations have made it seem that overkill was NECESSARY, rather than possibly desirable. It's only professional to inform first, and then recommend. I really have nothing against you guys personally... :drinkup:

Thanks for your good advice! ;) I've already learned a lot on this website.

[NnF]

:cool:

I again say that I am not an electrican but I do like to over build.

I own a Miller Mig 210 and I use two extention cords, 1-25 footer and 1-15 footer both 8 ga.

I have never had a problem with the machine with the machine or the cord even when connected together.

Over-Kill, YA, but, as said, "if I go to a larger machine I won't have to buy new cords" and now I don't have to worry about the machine getting enough current.

Luck,