DCC Bus Voltage-Drop Calculator

A long or thin DCC power bus loses voltage before it reaches the far end, so distant locos run weak and short-circuit protection gets sluggish. Enter your wire and run to see the drop and whether to go heavier.

Drop is round-trip (2 × length × resistance × current) against a ~14.5 V HO bus; 3% is the comfortable target. The current is the load on that bus run — roughly 0.3–0.7 A per running loco. More on DCC power in the glossary.