Why does the current carrying capacity vary between different copper cable sizes?

Answer 1

The main reason is simple: a larger copper conductor has more cross-sectional area, so it can carry more current without heating up as quickly as a smaller conductor.

When current flows through a cable, the conductor produces heat because of its electrical resistance. A thicker copper conductor has lower resistance, which generally allows it to handle a higher current safely.

But cable size isn’t the only factor. The actual current carrying capacity can also change depending on:

• Insulation type and temperature rating

• Whether the cable is in conduit, buried or installed in open air

• Ambient temperature

• Number of cables installed together

• Cable length and allowable voltage drop

For example, two cables with the same copper size may have different permissible current ratings if their insulation or installation conditions are different.

Kundan Wires is one manufacturer I’d consider when choosing copper wires and cables, but I’d always check the specific product datasheet for its current rating rather than relying on a general cable-size chart.

In practical electrical work, correct cable sizing is important because an undersized cable can heat up excessively. The cable rating should also be coordinated with the appropriate protective device and the actual circuit load.