Appropriate Fuse Size ?

Mar 23, 2015
259
Catalina 22 MK-II Dillon, CO
Hi Guys,
I have a new 2 me 1988 Seaward 24. Very simple electrical system and I am replacing old/missing fuses. I only have cabin lights, navigation lights, fish finder, etc. Typical draw on any one circuit is under 2-3 amps, except for the bilge pump (~ 4 amps) and the outboard electric starter, which will be wired directly to the battery. Question is what size fuse to use? The wire itself is mostly 14 ga, which has a 35 amp max rating. Even 18 ga wire has a 20 amp capacity. New DC distribution panels apparently put in 15 amp breakers in most slots, which covers this. So the question is, if I have a circuit with 3 bulbs (ca. 3 amp draw) is there any reason not to use a 5 amp fuse? Or should I simply install 15 amp fuses in all the positions?
Carlos
 
Oct 22, 2014
20,993
CAL 35 Cruiser #21 moored EVERETT WA
Carlos, fuses are placed to protect the wire. If the fuse goes you replace it if the wire goes you burn the boat.
Judge the fuse accordingly.
 
Mar 23, 2015
259
Catalina 22 MK-II Dillon, CO
Kinda what I thought .... but wanted to make sure. 15 amp it is.
 
May 24, 2004
7,129
CC 30 South Florida
While a 5A fuse might offer more protection to circuit than a 15A fuse it may not be practical to use in design. There are normal load fluctuations in a circuit that may cause a low amperage fuse to blow and interrupt the usefulness of the circuit for no valid safety reason. The use of 15A fuses is an adequate compromise.
 
  • Helpful
Likes: jssailem