Quote: Originally Posted by 01black_ac
For example, I'm going to use 8AWG wire over about 15' to power my Opus 120 (120Watt PSU). (I realize 8AWG is overkill for a 120W PSU, but I wanted the ability to add future devices later without having to run a new cable.) The Opus has an onboard 15Amp fuse, but its max draw is 10Amps... So wouldn't I want to use a 10Amp fuse on the 8AWG wire next to the battery? Or is it because the heat at 10AMPs will never come close to burning an 8AWG wire, so going higher than 10AMP fuse is perfectly safe?
I'm also going through a distro block once the 8AWG reaches the trunk. I was planning to load the distro block with a 10AMP fuse as well, but maybe I'm not calculating that correctly?
'01
Your Opus is already fused, so that's not a problem. The reason your adding another fuse is to protect the wiring. If your wiring shorts out 2" before getting to your Opus, it could start a fire. Your 8 gauge wire has a much higher amperage rating that what your Opus is going to pull, so you do have a lot of lee-way (sp?) there for the size of your fuse. Anywhere between 15 and 30 amps would be fine. I just wouldn't use a fuse that's exactly the same size as your Opus max rating. Give it a little bit of freedom. If Opus puts the fuse higher than it's max rating right from the factory, that there's no reason why you shouldn't do the same.