What size fuses to use?

[Rick Macdonald]

I blew the "acc" fuse while rewiring the autohelm 800 plug. (I haven't ever used the autohelm but I'm about to start playing with it. It came with my used boat).I stole the masthead/steaming ligt fuse for now, but I noticed quite a variety of fuses as I checked them all. They range from 5 to 30 amps if I'm reading them right. Well, ok, here's the list of what I found:running lts: 250V 5ACabin lts: 32V 7-1/2ASteam/Mast lts: 30Abilge pump: 32V 15AAcc: 32V 15A (this runs the BiData knot/depth, the AutoHelm 800 which I haven't ever used yet, a cigarette lighter socket with nothing plugged in but I assume I could plug in a power inverter such as my PortaWatts 300)There's nothing in my manual. How do I know what to use?

 

[Debra B]

depends on the device

You need to know how much each circuit draws, and then size the amperage of the fuse accordingly. For electronics, the mfg. usually says what type of fuse to use. This is why you don't want to wire just any 2 things together. For lights, the bulb should say wattage. Watts=Volts X Amps So you can figure out what you need.

 

[Ron Mehringer]

Amps

The primary purpose of fuses is to a prevent fire if there should be a short circuit. So ideally, you put in a fuse that's not too much higher than the maximum combined load of the devices on that circuit. To really do it right, any wiring on that circuit should be rated to carry at least as much current as the corresponding fuse. Otherwise one branch of the circuit could possibly draw more current than the wire could carry, and it would overheat, but the fuse wouldn't blow. When in doubt, start with a smaller fuse and if blows during regular use move up to a larger one. I believe failed wiring is the number one cause of boat fires. Wires often chafe thru the insulation, but since they are hidden the problem goes unnoticed.Ron Mehringers/v Hydro-Therapy

 

[arturo devitalis]

Same problem

Same problem. My 1993 manual does not list fuse sizes, and I know he previous owner monkeyed around with the panel, so I haven't got a clue what size fuse is needed for each switch. I'm going to phone Hunter and see what I can learn. Seems kind of strange for an owners manual to have a wiring pictorial layout stating 16 guage wire throughout, but no mention of fuses reqd.

 

[Ron Mehringer]

16 guage

Searching the internet, I found a site that says 16 guage wire can safely carry up to 22amps.Ron Mehringers/v Hydro-Therapy

 

[alan]

Don't forget to take into account the length...

...of the wire. In long runs you need to increase the wire size. alan