Am I calculating correctly?

**sonicdevo** · 10-01-2006, 04:20 PM

I've done my research the past few days, and I think I understand how to calculate the power draw from my batt, the wire gauge I need, fuses, etc.... would you guys tell me if my calculations look correct, or if I need to start over?

My Opus 150W PSU... that would give me 150watts/12volts=12.5amps ... over 15ft (to be safe) would be a 10 gauge wire ... 8 gauge to be really safe, right?
Then for a 600W amplifier ... 600watts/12volts=50amps ... again over 15ft, would put me right on the cusp of an 8 gauge, probably a 4 gauge wire.
THEN, the wire from the distro blocks to ground and batt would be the additive of these... 12.5+50=62.5amps ... over 15ft (again, to be really safe) would be a 4 gauge wire.
In the distro block, I'll need fuses of 20 amps and 80 amps ... and in the line from the batt, I'll need a 80 amp fuse.

Thanks for any help.

**PhilMayfield** · 10-01-2006, 09:26 PM

Not sure if Im reading it right, but are you wanting to run a 15ft ground wire?

Everything else looks good to me. And ya 4ga for the amp. Id suggest 4ga to a distro in the back. Then you can use 8ga for your shorter lines once back there. But no more than a couple feet.

**sonicdevo** · 10-02-2006, 01:06 AM

Yea, I just calculated the ground wire at this length to match the wire from the batt (unnecessary, I know) ... but adds an extra margin for safety. Thanks for looking at this for me! Looks like I'll be tearing my seats and carpet out tomorrow and going crazy!

**PhilMayfield** · 10-02-2006, 01:59 PM

Very cool, good luck on the install.

What I would reccomend for the ground situation, would be to have a ground disto block in the back where you have your power distro block. Then, ground to the chassis within 18in of the ground distro block. The shorter ground wire will help ensure you dont get any weird feedback.

I grounded mine under my rear seats. I drilled a hole, ground off the paint around it to guarantee I was getting a solid metal to metal connection, and mounted the ground with a couple washers.

**Bugbyte** · 10-02-2006, 02:32 PM

The ground distro block is helpful because it gives you a single point to ground to. If you ground to one part of the car, then another, it introduces the possibility of a ground loop.

Grounding to a single point will help prevent this.

Kudos to you for finding the info and figuring this stuff out on your own!