LED Strip Cable Size

Load current - I = P / U. With dual-end feed the cable runs to both ends of the strip from the same PSU, so the current in each wire is half - the same cross-section then reaches twice as far (or the same length needs half the cross-section). Wire size comes from the voltage-drop formula for a two-wire DC line: S = 2·I·L·ρ/ΔU, ρ = 0.0175 Ω·mm²/m (copper). The size is then also checked against the wire's continuous current rating - the result is never smaller than the wire size table allows: for high-current 12 V strips, sizing by voltage drop alone can under-size the wire relative to its safe current.

This only covers the feed cable from the PSU to the strip. The strip itself has its own trace resistance, and beyond about 5 m a single-end feed causes a visible drop toward the far end regardless of how thick the feed wire is - for longer runs, feed both ends or inject power every 5 m. Size the PSU with a 20-25% power margin over the strip's rating. This is a reference calculation; for critical installs (architectural lighting, large RGB runs) check the strip manufacturer's documentation.