Over Hill Sailing Club
Join Date: Feb 2009
Location: Adirondacks NY
Thanked 99 Times in 96 Posts
Rep Power: 7
This is really interesting...and a bit distressing because the amp ratings on these things seem to be largely meaningless. Why not call a 300 amp fuse a 300 amp fuse???? It seems a little silly (and dangerous) to call a fuse that will NEVER blow before 440 amps a 300 amp fuse. I have always ass-u-med that these physical fuses, in contrast to a circuit breaker, would be MORE accurate when matching wire sizes to circuit protection. It's like saying it's ok to put a 30a fuse on a #12 wire in your house--not a good idea.
The starter on my Yanmar 3GM30F has a current rating (from service manual) of "460a. or less" under a load, although looking at the torque curve, it appears that above 8v. it would never draw>350a. Even a 400a fuse would be cutting it close which is why I have a 500a ANL in place at present which will , in actuality only help for a dead short. Now...if a 500 amp fuse is ACTUALLY a 600 amp fuse, maybe I can knock it down to 400 amps (or even 275 if the chart is accurate), still well above 2/0 wire ratings but a bit less likely to melt off insulation in a partial short.
This is all a good reason to use additional conduit (as I mentioned above) to protect starter wires. If these things weren't so expensive, I'd like to experiment with them to get some real results.
Last edited by smurphny; 09-13-2011 at 01:22 AM.