One of the most essential (yet oftentimes overlooked) pieces of welding equipment is the welding cable, which is the conductor for the welding current. Welding cables are made of a series of fine copper strands which are wrapped inside a durable, non-conductive jacket made of typically natural or synthetic rubber in different colours. The copper strands provide the welding cable with flexibility, unlike other types of electrical conductors, and the insulating jacket is especially designed to withstand repeated movement over rough surfaces.
As the level of current increases (typically measured in amps or amperage), the diameter of the welding cable set and the cross-sectional area of the copper stranding needs to increase as well. The modus operandi is similar to how water flows through a hose, and as you know, you need a hose with a larger diameter to carry a higher volume of water. In other words, the fire department uses a much larger hose than you would use to water your garden.
That being said, the amperage rating (capacity) of the welding cable set refers to the maximum amount of current the welding cable can safely conduct. Some other factors that impact the capacity of the cable are the resistance rating, the length, temperature rating, ambient temperature and insulation material. Generally, shorter cables are capable of carrying more current than longer cables, provided that they have the same diameter.
The temperature rating of welding cables is usually either 75°C, 90°C or 105°C. And even though the copper wire can probably handle much higher temperatures, that would usually result in the insulation which protects the wire being damaged. Furthermore, the ambient temperature of the cable is usually 30°C, and any ambient temperature higher than that can negatively impact their ability to dissipate heat into the working environment, thus reducing their capacity. Additionally, multiple cables tightly packed together can also have a reduced rate of dissipating heat, so for that reason, they should be slightly spread apart.
Worth knowing is that even though copper is a great electricity conductor, it’s still somewhat resistant to the flow of electrons. That being said, some amount of resistance heating is inevitable. Furthermore, it’s perfectly normal for a correctly sized cable to feel warm to the touch after being used for a long time. However, if the diameter of the cable is too small for the amount of current flowing through it, then the cable can overheat and become a fire hazard or damage the cable. Additionally, the insulation jacket can breakdown and cause an electrical shock. On the other hand, if the diameter of the cable is too large, it’s very likely that it will come at a higher price because these contain more copper strands, which is quite cost-ineffective.