Grounding: battery vs. frame


Unregistered guest
when grounding audio components, is it better to use random points on the chassis, or to use a distribution block wired directly to the neg post of the battery (using large guage wire of course)?

i've read that grounding all components to a single point can help to eliminate noise and ground-loop problems. also, i would assume one could get extra points in competition for being creative and also for making the ground wiring accessible - like the power (+) wiring generally is.

Bronze Member
Username: Donp

Detroit, MI USA

Post Number: 12
Registered: Oct-04
The OLD school says to ground everything directly to the battery. I like running a thick #4 or larger from the negative battery terminal through the firewall and have a clamp to ground it there. Then, have a strap going off that wire to the in-dash player, then continue the wire to the amplifier in the rear. Also have a clamp to ground the wire to the chassis near the amplifier. That way the ground wire will be in parallel with the chassis and give you the best possible ground.

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4608
Registered: Dec-03
old school? who told you that one?
you keep the ground wires as short as possible, and ground to bare chassis metal.
the only time you'd go to the battery terminal is if you can't get to a metal ground any closer, such as in unibody fiberglass sportscars.

regardless of ground points though, ground your battery with the same size power wire you use to go to the amplifiers.
also recommended you use the same cable gauge between alternator and battery.

Unregistered guest
okay, the score is 1 to 1. any others?

question for glasswolf: is bare chassis metal a better conductor than pure copper? If so, please elaborate.

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4633
Registered: Dec-03
bare chassis metal is connected directly to the frame of the car (assuming the car has a frame of course.)
you just find a metal spot close to where the amp is mounted, make sure it's not directly over any brake, fuel, or electrical lines on the other side of the sheet metal, then sand or grind the paint off of the metal spot.
drill a pilot hole as needed, then use a self-tapping sheet metal screw or bolt to attach the ground cable via a ring terminal to the sanded metal.
that's how ya get the best ground point for an amplifier.
use less than a 24" run of ground cable if possible, and use the same gauge cable as you need for the power line from the battery or distribution block. (usually 8ga or 4ga)
The reason you keep the ground lines short is to avoid introduction of noise from other sources.
the more cable you use, the more chance of picking up EMI and RFI.

Unregistered guest
okay, but what about unibodies? there's no frame to ground to, so what then?

also, if you can pick up noise on the ground, can you pick up noise on the posi wire as well?

thanks for your input.

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4674
Registered: Dec-03
well, any time signal and power lines come within proximity of each other they can pick up noise.
that's what shielding is for, and why you run power and signal lines on opposite sides of the car.
as I said with a unibody you can run to the negative battery terminal, or use one of the bolts holding your seatbelts possibly.
always test ground points for continuity to be sure.

Silver Member
Username: Jeremyc

Kunsan AfbSouth Korea

Post Number: 113
Registered: Jun-04
I agree with glass again. Something else for you to remember is that electricity travels from ground to positive. Thats the reason you want the ground wire shoter to keep emi and rfi as low as possiable. The longer the wire the more it can pick up and the more it can introduce into your stereo.
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