One reason to use a fuse in addition to a breaker is to protect smaller gauge wire. In many panels (like mine) breakers are 15A, which would require all wire runs to be 10-12ga (maybe 8ga on larger boats for long runs) in order to supply 15A without wire damage. Of course, C&C didn't use this size wire for most runs, so to protect them, a small fuse sized for the intended load and wire gauge should be used. Otherwise, a short in the circuit could cause wire damage before a 15A breaker trips.
-- Shawn Wright shawngwri...@gmail.com S/V Callisto, 1974 C&C 35 https://www.facebook.com/SVCallisto On Wed, Mar 11, 2020 at 11:01 AM Dennis C. via CnC-List < cnc-list@cnc-list.com> wrote: > Dave, > > Piggybacking the supply from one fuse to another is pretty common, > especially in older boats. Just need to ensure the proper wire size to > carry the load to all the users. Pre-made breaker panels have a solid buss > bar which carries the power supply to each breaker. The piggyback wiring > is philosophically analogous. > > Personally, there are better ways to do it. If there's a place for a buss > bar, you can route the power from the rotary switch to the bar then connect > each fuse to a connection on the bar. I would not stack a bunch of > separate wires on the switched connection on the rotary switch. > > On Touche', I have a Powerpost Plus, which is on the switched connection > of the battery rotary switch. That is, when the battery switch is "ON", > the Powerpost is live. A properly sized wire from the powerpost supplies a > couple of buss bars in Touche's breaker panel. Each breaker is then > supplied individually from the buss bar. > > Not sure about your comment on a fuse before a breaker. A better pic > might help. > > You should have a fuse at the battery. I have these on Touche': > > https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A > > Dennis C. > Touche' 35-1 #83 > Mandeville, LA > > On Wed, Mar 11, 2020 at 11:58 AM David Knecht via CnC-List < > cnc-list@cnc-list.com> wrote: > >> I understand the wiring in general and how the circuit works. I am not >> sure what the logic is to have created the double crimp tabs in order to >> bridge power from one fuse to the other. I get that each fuse will >> function for the circuit that goes to the panel. What I am unclear on is >> #1, why have a fuse before a circuit breaker on the panel >> #2- is this the “right” way to accomplish safe wiring. I could instead >> bring separate wires off the + from the rotary switch to each fuse rather >> than the bridging setup if I replace the current fuse holders. >> >> Thanks- Dave >> >> S/V Aries >> 1990 C&C 34+ >> New London, CT >> >> _______________________________________________ >> >> Thanks everyone for supporting this list with your contributions. Each >> and every one is greatly appreciated. If you want to support the list - >> use PayPal to send contribution -- https://www.paypal.me/stumurray >> >> _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
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