While it is certainly true that the fuse (or breaker) must be small enough to protect the wire, I disagree that "the only question that counts is, what size is the smallest wire you are trying to protect".
I also take into consideration the load and size the fuse to carry the load but not much more. This adds a further safety margin at no cost. I think he rule about sizing the fuse for the wire stems from household wiring where the load is unable to be determined because one can plug as many (1500 watts seems to be the largest single load allowed by law) loads into a single wire as there are receptacles, so sizing the fuse to protect the wire is the right thing to do. But on a boat where most often the 12 VDC loads are hardwired this rule can be modified toward the side of increased safety. While here, I want to remind folks that electrical fires can happen even when the current flows are below the trip current of the protective device, so be careful out there... Norm S/V Bandersnatch Lying Julington Creek 30 07.695N 081 38.484W > That said, there should be no guess work on selecting the size of fuse > for any given application. The only question that counts is, what > size is the smallest wire you're trying to protect. Then, use a chart > to determine the ampacity of that wire. Then, install a fuse (or c/b) > that limits the current to that ampacity. The key concept her is, > fuses protect wires. Specificlly, they prptect wies from overheating > due to current overload. Wires run in places that are inaccessible, > and of course, if they overheat, that's where the fire will be, too. > > _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
