Right now i have 8 awg wire run.... but i was told running a 500w memphis power refrence amp i would need 4 awg... what would happen if i left the thinner wire in there ? just less risk of fire ?

 

I would go with 0 gauge or 4 gauge at least.

 

0awg for 500w? Maybe if your installing the amp in the trunk of a stretch limo... Depending on how long the run is 4awg would be more then enough. 8awg will work as well though you may be losing some power output. While it won't hurt to run a 0awg or 2awg it really isn't necessary unless you are running more power then that.

 

Wellyour right. Maybe 0 guage might be overkill, but it doesn't hurt to have the largest power wire you can get.ThenI guessitsdepending on the system your setting up.
BTW how do you like the sound of those JL audio speakers you got?

 

I love them! The 6.5s are so bright and clear yet not harsh at all. The highs and mids are unbelievable, and the bass is ok. The bass is better then I had thought from what I read online. I have them crossed at 100hz anyways. I was a little disappointed with the 6x9s as the highs aren't as bright but still very clear. But the mids and bass are very punchy. Sound quality is fantastic in both speakers. If I had to get any other speakers it would be JL C5s, but those are a little hard on the wallet. These speakers are a great value at only $180 a pair.

EDIT: Well 0awg is a lot of copper, and copper prices aren't exactly going down. I spent $20 on 0awg just enough to do the big three, so enough for an amp run isn't going to be cheap.

 

Id use 4 gauge. 8 gauge is a little slim for that draw and when you factor in the resistance built up over 20 feet of run, it could get a little tight.

There wont be any danger of fire if its quality wire but the added resistance can cause a pretty signifigant voltage drop by the time it gets to your amp which will cause a very noticeable lack of power.

 

i once was running 4 guage power wire and 8 guage ground wire. it worked but amp would cut off after knocking too long. after switching to 4 guage ground wire everything worked fine..

so stick to one size.

 

Yes definitely. Using a ground smaller than the power can cause issues cause you now have different resistance. Dont know if it can cause your car to blow up but can overheat the amp and make it cut off.

 

Im using 0 from the battery to about half of my car. then a distribution block to 4. Works good.

 

8ga. is @ 85% recommended capacity at 408W
6ga. is @ 85% recommended capacity at 561W
4 ga. is @ 85% recommended capacity at 714W
2 ga. is @ 85% recommended capacity at 969W
1ga. is @ 85% recommended capacity at 1122W
1/0 ga. is @ 85% recommended capacity at 1275W

These #'s are for 12V nominal using Type UF wire as a basis of comparison. This is the worst case for copper wire. I use 85% because that is what is used for maximum circuit ampacity vs. wire sizing for buildings. Info is from NEC, 2005.