Choosing the correct electrical cable size isn’t about aesthetics; it’s about safety, efficiency, and protecting your expensive appliances. In this guide, we’ll demystify cable sizing so you can power your projects with confidence.

You cannot choose a cable size based solely on the length of the run. You must calculate based on three specific factors:

| Myth | Reality | |------|---------| | “Cable ampacity tables are safe for any length” | Long runs need voltage drop check, which often dominates. | | “Copper is always best” | Aluminum (higher resistance) may be economical for large feeders (>50 mm²). | | “Neutral can be half size” | Illegal in many codes; must be ≥ phase for circuits with harmonics. | | “Buried cables run cooler” | Actually run hotter if soil is dry or clay – lower thermal conductivity than air. |