Understanding Voltage Drop in Welding and How Technology Can Address It | MillerWelds

Understanding Voltage Drop in Welding and How Technology Can Address It

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Learn what causes voltage drop and how technology can help make welders’ jobs easier and reduce this problem on jobsites.
The framing of a structural steel building as it is under construction.

Reducing voltage drop problems

The day-to-day challenges on a construction jobsite can take up a lot of time and attention. A shortage of experienced workers, demanding project deadlines and costly welding rework are all factors that affect how quickly you can finish one job and move on to the next.  

One common jobsite struggle that may fly under the radar — even though it can be an everyday hassle — is voltage drop in weld cables and the problems this can cause. 

Learn more about what causes voltage drop and how one technology can help make welders’ jobs easier and reduce this problem on construction jobsites. 

Signs of voltage drop problems 

Voltage drop is the result of resistance in the weld circuit. While there is always some level of inherent resistance in the circuit due to physics, some practices can result in additional resistance — and therefore more voltage drop. As voltage drop increases, it can become more problematic. 

Here are some common signs of excess voltage drop: 

  • Stumbling arc: The weld parameters being used should produce a good arc but if you see a stumbling or stuttering arc this may be a sign of problematic voltage drop. If you think you may have voltage drop problems, one of the first things to look for is an arc that is short or tight. Operators may keep bumping up the voltage to address this, but it’s really a sign of excess voltage drop somewhere in the circuit. 

  • Hot connections: If you feel a lot of heat at the cable connection or crimp, this can be a sign of overheating due to added resistance and excess voltage drop. 

  • Repeatedly Adjusting Voltage: If you’ve set a voltage at the power source but find yourself repeatedly having to increase it over extended periods during welding — this is a common sign of voltage drop. 

Common causes of voltage drop

Voltage drop can be caused by several factors on the jobsite. It often requires troubleshooting to find the culprits behind it. Following best practices and choosing the right equipment can help operations minimize the amount of resistance in the weld circuit and therefore the amount of voltage drop they see. How severe the voltage drop is depends on several factors. 

Consider these common causes of excess voltage drop:  

  • Undersized weld leads: When the cable isn’t large enough for the amperage being used it can quickly overheat, which adds resistance and increases voltage drop. To avoid this, don’t skimp on welding leads. Operations can set themselves up for success from the start by investing in properly sized leads. Welding power source owner’s manuals typically include weld cable sizing charts, so it’s a good idea to refer to that information. Also, be sure to include the entire weld circuit when sizing cables. Operators may forget about the work side of their welding cables when they are choosing cables or adjusting voltage. If they are 50 feet from the welding power source, they may estimate the voltage needed based on that 50-foot distance. But in reality, the cable runs out and back — the positive and negative cable — meaning there is 100 feet of cable to account for.

  • Long weld leads: On large construction jobsites, weld cables can be hundreds of feet long and strung out over several stories. Even when weld cables are correctly sized, if they are long this will cause more voltage drop. Try to upsize to a larger size cable to help reduce voltage drop on long leads.

  • Bad connections: A bad connection or damaged crimp on the copper lug can increase resistance in the circuit. Just because weld cables are new doesn’t mean the crimps that connect to the machine are in good shape. Be sure to check all connections for dirt or mud. These connections need good surface contact to provide the continuity necessary for the least resistance in the work clamp. Also, clamps should be appropriately sized so that they are capable of carrying the necessary current without adding resistance. One indicator that your connections or work clamps are bad is if they get very warm during welding. That heat is power that should be going to your welding arc, and it means there is added resistance in the circuit. 

  • Using less conductive metals and extra connections: Some operations use a steel strap to create weld circuit current paths. However, steel is not a good conductor of electricity, and it will increase resistance in the circuit. Be aware of multiple connections and also the material that the weld current runs through, as some materials conduct electricity better than others and multiple connections in the circuit add opportunity for additional voltage drop in the weld circuit and stray weld current paths.

Address voltage drop with technology 

In some cases, voltage drop reaches the level that it interferes with the welding arc or produces a poor-quality weld. When this happens operators must either walk back to the power source to adjust the voltage — which can be a game of trial and error that requires several trips to get the right setting — or they may need to radio a helper who will adjust the voltage at the welding power source for them. Either way, it is a time-consuming hassle. 

Cable Length Compensation (CLC™) technology from Miller eliminates these added steps and takes the guesswork out of addressing voltage drop — making it easier and more convenient for operators. As a result, operators stay under the hood longer, which improves the operation’s productivity. 

With CLC technology, the welding power source automatically calculates the amount of voltage drop in the circuit and adjusts the voltage as necessary, all while the operator is welding. This ensures that the voltage an operator sets is the voltage they get at the wire feeder. 

Having an easy solution to excess voltage drop reduces the effects this issue has on the welding operation — saving time and money, helping operators be more productive, reducing operator fatigue, improving weld quality and reducing the expense of repairing welds made with bad weld parameters. Operations should still follow best practices that help minimize voltage drop, but CLC technology removes the guessing game around adjusting voltage. It also helps produce the most consistent results. 

CLC technology is available on ArcReach®-technology enabled power sources and wire feeders from Miller, including the XMT® 350 FieldPro™ and XMT 650 ArcReach Systems designed for construction jobsites. 

Voltage drop problems and solutions 

Voltage drop is among the many challenges on construction jobsites that cause hassles and waste time. CLC technology delivers simplicity and consistency in helping address excess voltage drop — making it easier for operators to complete quality welds and stay under the hood longer. Reducing the effects of voltage drop on the welding operation can have a positive impact on the entire project, helping contractors complete jobs faster.