Originally Posted by Champ
This thread got me thinking.
My battery and master solenoid are rear mounted with a #2 wire to the engine side of the firewall where it connects to the starter solenoid and ANL fused #8 line back into the cockpit buss.
Is the master solenoid at the battery enough protection on the #2 line or should it also have an ANL fuse? It would have to be a pretty big fuse to handle starter current.
The master contactor is the 'protection'. It's accepted practice in certificated a/c. With proper care in routing and installation, you shouldn't ever have an issue, but if it somehow gets its insulation cut by a/c structure (typically a bulkhead pass-through), it'll quickly burn the hole big enough to remove the short. Sounds crazy, but the short to ground is effectively self fusing. You'll likely know it happened (;-) ), and can repair when safely on the ground.
An ANL fuse big enough to handle starter current will net you the same result as what I described above, if you had a fault to ground.