Selecting an incorrectly sized welding cable can be dangerous. The wires can overheat and burn the insulation layer, which leads to electric shocks and fires.
The correct size ensures safe and efficient welding. But, sizing a cable size is not straightforward.
So, we prepared this guide to help navigate the nuances and terminology that may confuse even experienced welders.
We also created a helpful chart to quickly find the right cable size based on your welding setup parameters.
What is a Welding Cable?
Welding cables, also called welding leads, connect the ground clamp and electrode holder with the power source (i.e., the welding machine).
Durability and flexibility are crucial aspects of welding cables. They must be resistant to cuts, wear, and insulation damage and flex and bend easily. You need to manipulate the welding electrode with ease and access every part of the welded joint. Imagine how difficult welding would be if the cables were too stiff.
Cable Core – Copper or Aluminum
Hundreds of finely-stranded wire conductors form the cable core. The higher the strand count of the cable, the better the flexibility.
Copper is a better conductor than aluminum. So, aluminum-core welding leads require a larger cable diameter than copper-core leads. But, aluminum is lighter and less expensive than copper.
Cable Insulation – EPDM, Neoprene, or PVC
EPDM and neoprene are preferred insulators for welding cables because of their flexibility and ruggedness. These materials endure abrasion, moisture, and dust and are good at preventing cuts and insulation breaks.
However, PVC is the best choice for tear and cut resistance. But it’s less flexible. If you weld in typical conditions, stick to EPDM and neoprene. But if you plan to work on particularly rough surfaces or harsh environments, the PVC insulating jacket is better.
What Size Welding Cable Do I Need?
Welding cable size depends on the maximum amperage output of the welding machine, the rated output duty cycle, and the total length of the welding circuit. But the current type (AC or DC) does NOT affect the welding cable size.
You may have heard that the cable length determines the cable size, but this is only half true. You need to take the entire welding circuit into account. This includes both welding leads, the ground clamp and the electrode holder.
The ampacity, also referred to as current carrying capacity, is the maximum amount of current (amperage) the cable can safely conduct without exceeding the rated operating temperature. Electrical flow generates heat, and you need a cable that will not overheat.
Some ampacity calculations rate cables only based on the cable length and wire diameter, which is not the most accurate way to calculate the cable size. As we discussed above, you need to consider the whole circuit length.
The ampacity rating decreases as the cable length increases. This drop occurs because the longer the cable is, the higher the resistance, which increases the operating temperature. If it gets too hot, the heat can damage the cable insulation.
But, as the welding cable diameter increases, the ampacity rating rises. There is less resistance to the electrical current flow if the cable’s cross-section is larger. Less resistance means cooler cable, which increases the ampacity rating.
Every welding machine is rated for an operating duty cycle. This percentage rating notes the portion of a 10-minute interval the welder can run at a specified amperage before resting for the remainder of the time.
For example, a 40% duty cycle at 200A means that the power source can output 200 amps for four minutes before resting for another six minutes.
The higher the duty cycle, the larger the cable needed. At a high duty cycle, the cable has an extended period to heat up beyond the safe temperature and a shorter time to dissipate the accumulated heat. So, you need a beefier cable with high-duty cycles.
Welding Cable Size Chart
The larger the cable diameter, the higher the allowed ampacity. Thin and long welding cables cannot carry high currents because there is too much resistance, causing the cable to overheat and damage its insulation. This is dangerous and can lead to fires, burns, or electrical shocks, especially since you are likely to make physical contact with the cable as you weld.
Complex calculations to select the cable size involve the machine’s duty cycle, maximum amperage output, circuit length, and cable diameter. Luckily, cable sizing charts simplify the process. But, before we show you a table covering most welding needs, we must discuss the wire gauge rating.
Cables are typically categorized by an American wire gauge (“AWG”) size. The AWG rating works in reverse — the smaller the AWG number, the larger the cable’s diameter. For example, AWG 20 cable has a far smaller diameter than AWG 5 cable.
But, there is an important AWG rating rule you need to know. Size zero is often referred to as “AWG 1/0,” not as “AWG 0.” So, “AWG 1” is smaller than “AWG 1/0.” Additionally, there is a double-zero rating “AWG 2/0,” triple zero “AWG 3/0,” etc. The cable diameter gets larger with more zeroes.
Be careful to avoid a classic beginner’s mistake. It is easy to read the chart below and determine you need an “AWG 3/0” cable but mistakenly buy an “AWG 3” cable. This would be a dangerous error.
The AWG 3 is six sizes smaller and could never handle the ampacity of the AWG 3/0 rated cable. So, pay particular attention and double-check you have the correct AWG-rated cable when ordering.
Extension cables work similarly to welding cables. Essentially, you need a cable that can handle the welder’s input amperage and voltage for the desired extension cable length.
We wrote a complete guide on determining the necessary AWG cable gauge, how to choose a cable to buy, and how to build your extension cord as a DIY solution.
Where To Buy Cables
Many tool stores sell welding cables, but it’s easiest to get them on Amazon because of the wide selection. We link to commonly used cables below, but you should know that welding leads are sold either standalone or with an electrode holder, ground clamp, lugs, and DINSE plugs.
If you buy cables at the welding stores, you have the advantage of buying by the foot. But, if you buy on Amazon and similar online stores, you will usually get a fixed length. Still, it’s more convenient to get the cables online, and you can save the extra length for other needs.
A Complete Package – 100 ft.Tweco Leads
- 100 FT Welding Cable - Size 1/0 Gauge
- Tweco 300 Amp Ground Clamp
- Tweco 250 Amp Electrode Holder
- Tweco 2-MPC-1 Cable Connectors
- (2 ea) Tweco 2-AF Lugs
This 100 ft. welding cable comes with a high-quality 300A Tweco ground clamp and 250A electrode holder. It also includes DINSE plugs and standard Tweco 2-AF Lugs if your machine doesn’t use DINSE connectors. The cable is AWG 1/0 gauge (AWG zero, as discussed earlier).
Many people don’t need a 100 ft. welding circuit, but this cable is still a popular choice because you can trim it and save the rest for future needs. Your welding leads are bound to break at some point, so it’s good to have a spare cable for replacement.
100 ft. EWCS 2 AWG Cable – Made in the USA
- Sunlight Resistant
- Water Resistant
- Highly flexible 30 guage copper stranding
- Ships as a coil
- Specially packaged and printed by EWCS to assure quality
If you need a cable to weld using about 200-250A at 30-60% duty cycles, this AWG 2 cable from EWCS is a good choice. It has a 100% copper core and offers excellent insulation and conductivity. Plus, EWCS cables are made in the USA and they specialize in cable production.
But if you need more amperage, the same brand also offers a flexible, durable AWG 1/0 100 ft. cable.
Welding cables must have an adequate diameter for your specific setup. The cable length, amperage, machine’s duty cycle, and the cable’s insulation rating dictate the necessary size.
The larger the diameter (e.g., the lower the AWG rating), the higher the amperage the cable can transport over longer distances and at a higher duty cycle.
If you are ever in doubt, it’s best to choose a cable one-size larger.
Cable ratings are not always 100% accurate, and they are usually rated at a 40 Celsius ambient temperature.
If you weld in an area with a higher temperature, you’ll need a slightly thicker cable. So, it’s always a good idea to go with a larger diameter, if your budget allows it.