: Aluminum has higher resistance than copper. An aluminum cable must be roughly 1.5x larger to carry the same current as copper.
Disclaimer: Values are approximate and vary by specific manufacturer and installation conditions.
Ensure the cable is thick enough that the voltage doesn't drop more than 3–5% over the length of the run. cable size and current rating
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| Scenario | Action | |----------|--------| | Run length > 30m | Increase 1–2 sizes | | Ambient > 40°C | Increase 1 size | | More than 5 cables in trunking | Increase 1–2 sizes | | Motor or compressor (high start current) | Increase 1 size | | Cable passes through insulation | Increase 2 sizes | : Aluminum has higher resistance than copper
Example Approximation (for Copper Wire in open air/conduit):
The current rating is not a fixed number for a specific cable size. It changes based on the installation environment. Ensure the cable is thick enough that the
Engineering standards such as the or BS 7671 dictate specific sizing rules: