How Long Can Welding Leads Be

Weld for long enough and you’ll probably find yourself in a situation where the item you need to weld is not easily accessible. There are times where you would love to just be able to unspool a couple hundred feet of lead instead of trying to drag that giant car frame just a little closer. While talking to other welders, I’ve come to realize that a serious question that a lot of people have is how long should the welding leads be. Can I just have a huge spool of lead wire? While there is no simple answer to this question, there are some guidelines that you can use that will help you guarantee the least amount of power loss possible. The problem most people run into is when the welding lead starts to get too long and the resistance of the wire comes into play. Because of this they can wind up losing power which will prevent a quality bead from forming.

Having said that, most people only use between 10 and 25 feet of welding cable and for these distances, the amount of power loss would be negligible. There are also discussions about should the leads be different lengths. The only reason that the leads are typically different lengths is that the ground wire doesn’t need to be as long as the stinger wire. The stinger wire will be a bit longer so that you can move around the bench or whatever you’re working on and have the ability to attack the situation from different angles.

The ground wire typically only goes to the bench or one spot on the piece that they are welding. Many people suggested that it should be a 70/30 percentage between the ground wire and the stinger wire or a 60/40 percentage. As far as I know, there are no limits on lengths when it comes to this aspect of buying a welded lead.

Why do Some Welding Leads get Hotter than Others?

As stated above, the longer leads have more resistance (longer wire=more resistance). The higher your resistance the lower your current. The welder will provide a constant voltage. Since V=IR, that can only mean you will be losing juice. The way to get around this is to use a heavier gauge cable. You want to make sure that the cable is capable of properly handling the amount of current that your welder is able to produce. The last thing you want to do is ruin one of your welding leads. If they are not big enough to handle the current that is flowing through them, they can overheat.

Any welding lead will be warm to the touch after prolonged use, however, if they get overheated it can lead to current variations which will cause weld deformation or physical damage to the leads. The higher the power loss over the cable, the more heat it creates. The equation for voltage is current multiplied by resistance. This is why resistance plays such a heavy roll. If the resistance of the lead exceeds a certain amount and the powers loss goes up, it will produce a great deal of heat.

The fix for this is to use a heavier gauge wire which will allow for better current flow and less resistance. Older wires can also cause this because they can become corroded which can cause resistance to build up in the current flow. When you replace your cables on your welder, make sure that the wire you buy is rated for what you will be using it for. Plus, you want to make sure that the new connections are corrosion free and clean so that they will conduct electricity properly.

How Does Length Affect Welding

When you’re calculating the  amount of power produced by a circuit, you start with the voltage and divide that by the resistance of the cable. In this case, the resistance is variable depending on the length and gauge of the welding lead. Take the voltage that will be going through the lead and divide that by the current going through the lead and it will give you the resistance. The higher the resistance, the harder it is to get current through the lead. What this means is that your cable is going to be hotter. If you do this over a long period of time, there will be damage to the welding cable itself and possibly even the machine.

However, these are not the only issues that can arise from using the wrong gauge of wire. You will also get a fluctuating current coming through the cable which can cause issues with the weld as well. These means that you will have issues like inconsistent welds, for instance, welds that look like a rope sitting more on the metal, a weld that is to spread out and looks thin, and there is even the possibility that the weld will be weak and have surface cracks in it.

This is why it is very important to choose the correct size welding lead for your machine. If the gauge of the lead is too small and the lead is longer, then the resistance will be higher and this will directly affect the heat that is produced by the unit. This includes the couplings that connect the leads together. If you’re going to have a longer run of cable, make sure that it is one continuous run.

What if I Will Never Use the Higher Settings on My Welder?

It is recommended that you always use a cable that will handle the maximum voltage produced by your welder. However, if  you know that you will never use the higher settings, it is feasible to buy a cable that will only support those settings. There is however an addendum to that, if you ever do decide to use the higher settings and you forget to change the cable before doing so, this can cause the problem that we’ve been discussing. Not only are you likely to damage the cable that you’re using, but you could irreparably damage the welding machine as well, so it is still recommended that you go with plan A and buy a cable that will support the entire load.

What if My Welder Produced up to 350 Amps?

If your welder produces up to 350 amps, it is considered a personal or commercial use unit. At 350 amp, it would be running at about a 60% duty cycle. Of course, the factors that I’ve mentioned above will come into play. Anything up to 100 feet of welding cable uses a 1/0, but then the size goes up the further you go. Anything 100-200 feet, you will need a 2/0 and from 200-250 feet,  you will need 3/0. This is not the norm though, for the other machines, you want to break the leads down into 50 foot increments.

For instance, with a 125 amp machine that is running 30% duty cycle from 1-50 feet, you would use a 6-gauge welding lead and from 51-100 feet, you would use a 5-gauge welding lead. From 101-150 feet, you will use a 3-gauge welding lead and from 151-200 feet, you should use a 2-gauge welding lead. Finally, from 201-251 feet, you will use a 1-gauge welding lead. I am not adding any longer leads then that because if your leads are that long, you need to either move the machine or get another one.

Cable Gauge in reference to length and current.

Recommended Sizes for welding leads that are rated 75⁰ C *

These are the combined lengths of the work lead and electrode.

Current (amps)Duty Cycle (%)1-50 feet51-100 feet101-150 feet151-200 feet201-250 feet
600603/03/03/04/02  2/0
6001002  1/02  1/02  1/02  2/02  3/0
650603/03/04/02  2/02  3/0
7001002  2/02  2/02  3/02  3/02  4/0
8001002  3/02  3/02  3/02  3/02  4/0
10001003  3/03  3/03  3/03  3/03  3/0
12001004  4/04  4/04  4/04  4/04  4/0
15001005  4/05  4/05  4/05  4/05  4/0

These values come from

How Can I Tell If My Welding Leads Need To Be Changed Out?

There are several different variables that can come into the equation when it comes time to replace your welding leads. I know people that have been using the same welding leads for 20 years or better. This doesn’t mean that it’s a good idea, but some welding leads do last longer than others, especially if the welding machine is not used frequently. Once an individual starts having a problem, they do not want to blame the welding leads because they’ve been working fine for so long. This is actually what can cause the welding leads to become inoperable or damaged.

Look at the shielding around the cable, do you see any breaks? Is there any wire exposed and do you see any corrosion built up around the ends of the leads? These are all good signs to look for when deciding whether or not your welding leads need to be replaced. Having said that, there is a way of telling how much resistance the lead has built up. In order to check the resistance of the lead, you need both ends and an ohmmeter. Checking a lead from end-to-end with an ohmmeter will give you a resistance reading. Every cable will have a certain amount of resistance per foot. using the chart below, calculate the resistance that your cable should have and see how it compares.

The Measurement that Maters

If you noticed that the resistance is a good deal higher than what it should be, then you need to replace your cables and possibly even your connectors. The following values are taken from “Electric Welding” on page 18, published by Ethan Viall, McGraw-Hill in 1921.


Quality and Safety

Anytime you replace the welding leads on your machine, you want to make sure you’re getting the right gauge of cable that will support your machine. You also want to make sure that it is of good quality. Products that are not designed or manufactured the right way can also cause a problem. Make sure to read reviews and see how they stack up to others in the same category. Plus, if you’re going to replace your connectors, you want to make sure they are of good quality as well.

A higher price doesn’t necessarily mean a better quality, you could just be paying for the name. I have known a few welders in my life that preferred some of the cheaper connectors because they offered advantages that the more expensive ones did not. For instance, one brand they used to use had two hex head screws that secure the cable into a connector instead of just one. This made a safer more secure connection.

In Conclusion

In doing the research for this article, I’ve come across many principles that I had not used or thought of before. Before this, I’d simply changed my cables every so often to see of it solved a problem. Now, I have a way of telling whether or not my cables are they issue. Having said that, there are other things that I take into consideration and not just the resistance. Welding leads do get damaged occasionally and I’m not one to take a risk on something like that. Safety is very important to me and I want to make sure that anybody else around me will not get hurt either.

Having said that, once you have learned about properly testing your leads and about the correct signs that tell you when you need to replace them, it actually makes your welding experience a lot better. The hope for this article is that you will be able to take the information that I provide and use it to improve your process. Welding leads that are old or damaged can cause different types of welding issues which in turn can cause a good amount of frustration to the end user. If you are noticing any of the symptoms that I have outlined in this article, check your leads out. If you do find that your welding leads need to be replaced, now is as good a time as any. So let’s replace your leads, find a project, and get to enjoying that welder again.

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