Ground Length?

[terra 5,000+ posts]

i always hear people saying keep the ground as short as possible...but then why is grounding to your battery a good idea? isnt that even further away?

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[IgnoreMe 5,000+ posts]

it doesnt matter.

making your ground less than 3' like everyone suggests doesnt do jack shit, because all your really doing is splicing into the chassis which will act like a wire extension (just like doing a full 1/0 ground run) that grounds the amps to the battery anyway.

i prefer a full ground run because i dont trust my chassis. if you got a full on frame and can utilize it, you can save some cash on wire and use the frame.

 

[helotaxi 5,000+ posts]

The ground is to the battery one way or another. Whether it goes from the amp to the chassis via a section of wire and then through the chassis to the battery via another wire or from the amp direct to the battery via a single run of wire, the result is a ground to the battery.

 

[terra 5,000+ posts]

ok thanks

 

[indosia 10+ year member]

They are talking about running an additional ground wire directly to battery. Why do you ask?

 

[squeak9798 5,000+ posts]

The idea is to have a ground path with the least resistance. The 3' rule is really just an arbitrary number that was essentially pulled out of the air.....no real basis for that specific length.

But the general idea is that the "wire" used for the ground from the amplifier will generally have more resistance than the chassis/body of the vehicle. So in order to have the least resistance, you would want to have the higher resistance medium (the wire) as short as possible and utilize the lower resistance medium (the chassis/body) as much as possible.

However the chassis/body can be a very poor conductor in some vehicles, which makes the use a dedicated ground wire back to the battery a better option. Also some people run large enough ground wire that the wire's resistance might actually be less than the resistance of the vehicle's chassis/body, even if it's a reasonably good conductor (as far as chassis' go). I've seen conflicting reports on the resistance of vehicle's chassis.....some state it's equivalent to ~17' of 2/0ga wire, others state it's equivalent to ~17' of 4ga wire.....and both were reliable sources. But regardless, if the wire itself has less resistance than the chassis (i.e. if your vehicle's chassis is equivalent to 17' of 4ga wire in resistance and you are running 1/0ga wire), it's a better choice to run the wire directly to the battery.