rotaryrocket7

So I have a small issue. I have 4 guage wire running to a distribution block, which has 4 8 guage outputs. I have 3 amps, 2 of which accept 8 guage wire, the 3rd takes 4guage power and ground.

I've run the system with 8 guage going to every amp, and everything works fine.


Can I run 2 8 guage wires to the power input of the amp that accepts the 4 guage... I don't see why this wouldn't work, but I'm no expert.

Thanks for any input.

PS, I considered replacing the main power wire, dist. block but couldn't find the parts necessary in the time required.

DHCrocks

what kind of amps are those? A single 4ga seems to be undersized for 3amps unless they are low power.

Lsmith9523

Rotaryrocket,,,,Running two 8g wires to the 4g power input of your amp will do very little. The need for a 4g set up is to allow sufficient power to pass to the amplifer. Also,,,as DHCrocks said above,,,,powering three amps off of one 4g supply from the battery is straining your electricial system. Have you thought about running 0/1 g wire from your battery to distribution block? Just a suggestion...I hope this helps,,and I am sure there will be other people that will offer more help as well...Good luck,,,let us know how things turn out.

rotaryrocket7

I'm running about 1100 watts, with a 12 foot run of main power. Based on 12volt.com's power size grid I should be borderline between 4 and 2 guage wire. The sub amp is digital, so its pretty efficient compared to a class AB.

The amps are PPI (these are pre-directed electronics taking over at PPI, so pretty good quality) and Phoenix Gold for the sub amp.

Help me understand why running 2 8 guage wires to the amp that accepts up to 4 guage won't help. If I essentially double the amount of area to transfer power via two 8 guage wires, why wouldn't I transfer more power than a single 8 guage wire?

Thanks for the responses!

DHCrocks

since you're running over 1000W you should be either running a single 1/0 gauge and spiltting it in the back or two 4ga and using one for the sub amp and splitting the other for the two smaller amps.

two 8ga is not equivalent to one 4ga, the cross sectional area is much smaller. Also don't forget that your grounds should be the same size as your battery connections.

tattoo60012

Just as an FYI two 8 AWG wires is actually better than one 4 AWG wire. Check it for yourself if you don't believe me but nominal AC ampacity of 8 awg wire is 40A @ 60 Deg. C If you use 2 wires that gives you a nominal ampacity of 80A @ 60 Deg. C (and yes it does work that way REF: NFPA 79.1 wiring for industial electronics) Nominal Ampacity of 4 AWG wire is 70A @ 60 Deg. C. I know the circular mils of a single 4 AWG is greater than that of two 8 AWG, the higher ampacity is due to the greater external surface area of the wiring to disperse heat.

On a completely separate point however, you may wish to check your ground wire going from your battery to your chassis. Remember you are only as strong as your weakest link. If your battery cable to the chassis is 4 AWG there is no point in going larger than that on your power wire because your return is your limiting factor, for that matter it doesn't even make sense to use a 4 AWG wire because the balance of the load from the rest of the electrical system in the car is sharing that single ground effectively de-rating the maximum usable ampacity of your ground lead. It's like having a 2" supply line going into your sink, and a 1/2" drain, you are limited on both sides of the load, so don't overlook that side of things. Everyone always says bigger is better, which in general is true, but there is a limit and then you have to start changing more stuff.

rotaryrocket7

I did replace the big 3 with 4 guage (i.e. alternator to battery,battery to ground,etc...) so my power and ground through the system are the same. Based on Tattoo's response I'm going to hook up the 2 wires and see what happens. Like I said before, it worked for over two years with a single 8 guage wire running to the sub amp...so it'll work now as well...I hope j/k

Thanks everyone for the feedback

StreetOC192

iTrader: (7)

About a 1/4 of the way down this page: http://www.bcae1.com/wire.htm shows that over a 15 foot run, 4awg will show a only 1/2 volt drop up to 131 amps. It is my belief that you can't say "you should run 0awg wire for over 1000 watts". I believe it should be determined by the amp ratings of the amplifiers used. Some class amps are more efficient than others.

To the OP: Add up the fuse ratings of all 3 of your amps and refer to the chart on the page I linked above.

StreetOC192

iTrader: (7)

Or better yet, Here is a graphic that you can input your info and it will recommend what the minimum wire sizes are:
http://www.bcae1.com/images/swfs/sys...nassistant.swf