If I have a fuse near the battery on a 4 guage that runs to a distribution block in the trunk, do I also need fuses on the power line of each component that gets power from the distribution block, even if each component has (a) built in fuse(s)?

 

as long as you have the fuse up near the battery you are fine

 

No need for extra fuses when you already have the main one...it just adds to what you have to troubleshoot if there's a problem.

 

Any drawback to using a circuit breaker near the battery versus an inline fuse? (other than cost)

 

No actually to me they're a great idea. You can break it whenever you want and if it pops, you just reset it. Come to think of it...maybe i'll get one

 

If you are using a distrubution block to smaller gauge wire for the components you should be using fuses. The fuses in the power wire system are not to protect the amps but for the wires themselves. So it is possible for the main fuse to protect the 4 ga wire, but have too high an amp rating for what the smaller 8 ga wire can handle.
Obviously it's not an absolute requirement and will work without extra fuses, but the idea is the extra measure of safety.

 

What exactly would you be protecting the wires from?

 

Overload. It's the same reason for the main power wire fuse. Example.. if for some reason a wire gets cut and exposed to direct ground without a fuse the wire will overheat and burn up, melting the plastic coating if you are lucky, starting a fire if you are not

 

getting hot and melting

 

http://www.bcae1.com/fuses.htm

That's why the main power wire fuse is supposed to be as close to the battery as possible ( i believe the standard is 12" or less) because it is unprotected from the battery to the fuse.

 

Uhm, more like, if a wire gets cut and hits ground the MAIN FUSE will break and the wire will no longer get power.

It doesnt matter where the power wire is, how big it is or how long it is, how many times its been distributed. If it touches ground, the main fuse will pop. That will end power throughout the entire circuit.