Cable Size Chart [exclusive] Jun 2026

When in doubt, always consult with a licensed electrician. Electrical codes (like the NEC in the US or BS 7671 in the UK) are the final authority on safety. Use this guide as your roadmap to understanding the logic behind the wires that power your life.

(one-way distance from breaker to load). cable size chart

Approximate rule of thumb for copper:

Even if the wire doesn't catch fire immediately, chronic undersizing degrades the insulation over years. This can lead to a short circuit years later in a wall where you cannot see it. When in doubt, always consult with a licensed electrician

Below is a comparison chart converting AWG to Metric sizes, along with their typical ampacity (current-carrying capacity) for standard copper wires. (one-way distance from breaker to load)

This is the #1 mistake DIYers make. A cable is a resistor. The longer the cable, the more resistance it has. Resistance drops voltage.

You cannot choose a cable size based solely on the chart above. You must consider three specific variables for your specific project.