Most RMS power on an 8 gauge wire?

[RSDXzec 10+ year member]

I'm considering upgrading to a second sub so I'll be going from 350W RMS to 700W RMS. I set my amp by multimeter so it shouldn't see any more than 700watts. Problem is I have 8 gauge wire and I know 700W is on the edge for this thickness. Should I be alright on this wire? do I really need to upgrade to 4 gauge?

I have a 60 amp fuse on it which came with my wiring kit and 700W/14.4V = 48.6Amps

Cheers.

Click to read more...

 

[05fronty 5,000+ posts]

you may get by dep on length. i would go bigger though. i use 8 gauge for my sub speaker wire ha

 

[akheathen Premium Member]

it doesn't quite work like that with amp current draw. the amp is not 100% efficient, so i would have to say it should be pulling up to 75-80a continuous at 700watts, depending on the amp. even at 60a, 8awg would be strained, and may see some voltage drop, and shortened life. i would suggest 4awg, or a second run of 8awg paralleled.

 

[chillin 10+ year member]

It depends on the length of the wire, but unless it is really short, i wout get some 4 gauge. Check out the bottom table in the link, and remember as said above, your amp is not 100% efficient so the input power will be about 25% higher than output.

Wire Gauge Tables

 

[TheUnderFighter 10+ year member]

Yea that's pushing it. I'd run 500w at most on 8 gauge.... I think you're best off just going with 4 gauge to ensure your best chances of safety, efficiency, and power.

 

[pro-rabbit 5,000+ posts]

What kind of 8 gauge wire do you have?

I would upgrade though, 4 gauge is a little "over kill" for that so you could get by with picking up cheaper 4 gauge and being just fine.

 

[RSDXzec 10+ year member]

ok now that you bring up the efficiency of the amp I will definitely be getting 4 gauge wire. But this raises another concern for me... my alternator is rated at 50Amps so I'm not sure if it would handle it. My battery is pretty decent with 330CCA and 55RC, and considering the alternator should have enough time between bass hits to recover, should I be fine on this electrical?

My speaker amp is rated at 45W RMS x 4. It's a very old car so there is hardly any power draw from anywhere else other than the audio system.

edit: I'm not sure what type of 8 gauge wire it is, I wasn't aware there were different kinds, but it came in a Fusion 8 gauge wiring kit.

 

[akheathen Premium Member]

what car is it? i would guess you are going to see a lot of voltage drop, and it would not hurt to up-size the battery.

 

[RSDXzec 10+ year member]

what car is it? i would guess you are going to see a lot of voltage drop, and it would not hurt to up-size the battery.

It's a 1984 Holden, I'm getting a voltage gauge at the end of this week to see how much voltage drop I'm getting with a single sub, then I'll decide If I go up to two subs.