i just wanted to doubble check with you guys to see what fuse size i should be using for my subs. i have 2 10in subs powered by a 275watt amp. im using an 8 gauge wire with a 30amp fuse right now without any problems.

I run that size fuse as well with about a 300 watts RMS system, though I'm using four gauge wiring. Eight gauge wiring supposedly has a current capacity of 100 amps, but I'm not sure if wire length has to do with this.

i thought the fuse size has to do with ur amp(s)... so whatever is on ur amp u would get one that is equal (or less) than ur amp... 30amp fuse seems real small...

Go by the fuse size on the amp. If the amp has a 40 amp fuse run a 40 amp on your power line. If your amp has two fuses say two 20amps add them up 20+20= 40 again use a 40 amp fuse and so on...

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This is what i go by. I also go with same size ground wire as power. that gauge wire btw is fine for that high of a load. A good unproffesional way to check it, is after you listen to them for a while, touch the wire, see if its warm, if so you may consider replacing it with a bigger gauge. But you should be fine.

You are fusing for the wire not the amp....

The amp already has its own fuse. You are fusing the power cable in the event the power cable might get a slit in it and short itself out to the car body which will quickly turn into a fire.

Fuse as close to the power source as possible as the length of cable before it is still unprotected.

From http://www.bcae1.com/
Wire Gauge Recommended
Maximum Fuse Size
00 awg 400 amps
0 awg 325 amps
1 awg 250 amps
2 awg 200 amps
4 awg 125 amps
6 awg 80 amps
8 awg 50 amps
10 awg 30 amps
12 awg 20 amps
14 awg 15 amps
16 awg 7.5 amps
These are the recommended maximum fuse ratings for the corresponding wire size. Using a smaller fuse than what's recommended here will be perfectly safe.