BoatHowTovideo
Should Fuses protect DEVICES or CABLES ?? 🤔 | Ask The Expert with NIGEL CALDER
June 28, 2025 · 3 min · 4K views
What this video covers
Fuses and circuit breakers protect conductors, not the devices at the end of a circuit — a point Nigel Calder calls a common and complete misunderstanding among sailors.▶ 0:35 A short circuit can drive hundreds of amps through a conductor, melting it along its entire run back to the battery; if that conductor runs in a bundle, it melts adjacent conductors and triggers multiple simultaneous short circuits.▶ 1:13 The fuse or breaker must sit at the source-of-power end of the circuit, not in front of the load, so it can interrupt the high-current flow before the conductor fails.▶ 1:46 Placing a fuse directly ahead of a device protects nothing upstream.▶ 2:27 Jan Attenstedt and Calder note the rule applies equally to DC and AC circuits, and that the fuse must be within a few centimeters or inches of the power source when exact placement is impractical.▶ 2:14 The discussion references the BoatHowTo Boat Electrics 101 course and a free primer article by Calder for detailed guidance on overcurrent protection device placement.▶ 2:58
More from BoatHowTo
From BoatHowTo — see the channel’s boat, crew, and every analyzed video.
The Sailing Directory Newsletter
One email with the fleet's best finds — the moments, boats, and stories worth your watch time. Enter your own address to get your own copy.