Originally Posted by josrulz
I have a follow-up question, which I believe is directly related to Maine Sail's post. Perhaps someone here can help.
Our boat has no fuses on primary battery cables, as was common in 1984, but I'd like to remedy the situation. I plan to install a negative busbar and a positive bus bar adjacent to the house bank, and use 1/0 cable for all the battery cables. If I protect the house bank between the POS bus and the house batteries with an MRBF fuse, do I need a fuse in the cable between the POS bus and the battery switch? The cable will be the same, 1/0. Since it's the same size wire, wouldn't the MRBF fuse at the battery protect it?
Yes it will. If the wire is all the same then one fuse can protect from the switch to the battery BUT if you pull other loads off that buss bar then they need to be protected for the wires ampacity rating. If you lowered the ga of the wire from the buss bar to the switch from 1/0 to 1ga then you'd need a smaller fuse unless the fuse protecting the 1/0 was not to the max of the 1ga wires ampacity limit.