power wire size?

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Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=115715
Printed Date: May 11, 2025 at 2:18 AM

Topic: power wire size?

Posted By: boatcapt
Subject: power wire size?
Date Posted: August 17, 2009 at 10:53 PM

I'm about to install a amp with two 20A fuses and a amp with two 25A fuses, 4 gauge should be sufficient for this. But my question is down the road if I upgrade the first amp to a amp that has 3 35A fuses would 4 gauge do the job? It will be about a 7 or 8 foot run. I guess the question is how many amps is the 4 gauge good for on this length of run? Awesome forum by the way.

Replies:

Posted By: audiocableguy
Date Posted: August 17, 2009 at 11:30 PM

I'm on the conservative side:
100 Amp 4 AWG
200 Amp 2 AWG
300 Amp 1/0 AWG

Assuming a 5% voltage drop @ 15 feet.

With the upgraded amp I would run 2 AWG with a 150 to 200A Fuse.
Remember to fuse every time you change wire size.

Posted By: KPierson
Date Posted: August 18, 2009 at 5:14 AM

Max amperage for a 4awg wire is 150A.

Your "proposed" setup is fused at 155A at the amps themselves, which means you could get away with running a 150A main fuse.

This would be pushing the limits of the 4awg wire and I, too, would recomend just putting in 2awg now so that you have some flexibility in the future.

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Kevin Pierson

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