Quote: Originally Posted by Pepe
http://www.rbeelectronics.com/wtable.htm
(Third chart down)
These values are just recommendations, as you'll find lots of charts like that all over the net with different recommendations, but I've found this one to be the best IMO. But I always choose wire at least one gauge larger than what it shows, then select a fuse that's more than the current value your going to be drawing and at or below the rating of the wire.
So for example, if your computer is going to be pulling an average of 20A
@12V over a length of 20' of wire, the recommended gauge is 12. I would then use 10 gauge (slide down to the next lower gauge on that chart under your length), and add a 30A fuse.
Sure there will be people that say "I've ran this and this off that gauge wire for years with no problem...", but a little extra resistance in the wire can make a big difference, resulting in the possibility of your wiring catching fire.
Okay, so I guess I'm still not entirely clear on something. I see from the chart you linked where you would get 12AWG wire over 20' when drawing 20Amps, and I understand dropping to a slightly heavier AWG just for a little added buffer... But why the 30Amp fuse if you've already stated the system will be drawing only 20Amps...? Isn't it safer to have the fuse as close in Amps to what you're actually going to be drawing as possible?
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