The cable, not the appliance. A fuse is sized so that it opens before the wire it feeds can overheat, which is why it belongs as close to the battery as possible — the length between the battery and the fuse is the only unprotected part of the circuit.
Protection is the part of an installation that does nothing at all until the day it does everything, and it is the part most often sized by guesswork.
Why the cable is the thing protected
An appliance has its own internal protection or its own failure mode. The cable does not: it simply carries whatever current is asked of it until its insulation gives way. Sizing the fuse to the cable is what stops a fault from becoming a fire, and it is why a bigger fuse is never an upgrade.
Why position matters
Everything between the battery terminal and the fuse is unprotected, because nothing stands between it and the full current the bank can deliver. Installation guides therefore speak of centimetres rather than convenience.
DC ratings are their own thing
Alternating current passes through zero a hundred times a second, which helps an arc extinguish itself. Direct current does not, so a switch, a breaker or a fuse intended for mains use is not automatically suitable on the battery side. Devices made for this work say DC on them and give a voltage.
What else belongs in the circuit
An isolator so the bank can be disconnected deliberately. A holder rated for the fuse type rather than the nearest one that fits. Terminals that clamp the full cross-section of the cable. The manufacturer’s instructions for each component describe how it is meant to be installed, and they do not all agree with each other — which is the reason to read them rather than assume.
What people ask before they order
Can an AC-rated fuse be used on a DC circuit?
Not interchangeably. Direct current does not cross zero, so an arc is harder to extinguish, and fuses and breakers carry separate DC ratings for that reason. The rating printed on the part is the one that applies.
What is breaking capacity?
The largest fault current the device can interrupt safely. A battery bank can deliver an enormous current into a short circuit, which is why this figure matters more here than in most other wiring.
Last reviewed 16 September 2026