View Full Version : Ground for amp

07-06-2009, 03:59 PM
Everybody ok running amp ground to battery?

Second, will too small a ground wire cause cut out?

07-06-2009, 04:36 PM
Running ground to the battery is fine. 4 gauge best, 8 guage ok, if it's a short run.

07-06-2009, 04:38 PM
Thanks - I am going to try that route before buying new speakers - that and replacing speaker wires as you suggested.

07-06-2009, 04:45 PM
Good luck. I just installed my third amp in the boat last week so I'm pretty familiar with the boat innards. You can get away with a pair (1 positive/1 negatieve, depending on the number of amps) of 4 gauge wire, and using a distribution block. 4 gauge in to two four gauge out per line. Not sure if I'm making sense or not, but let me know if you have any questions

07-06-2009, 04:59 PM
I have one of the distribution blocks mounted right to the terminal. But I am quite sure (boat is in a boat house) that the negative goes right to the negative terminal, no distribution block. This has worn us out for about 3 years - we have replaced amp, head unit, all wiring, just hard to narrow down - I think we had a problem we fixed, and now have another issue.

What do you think about cutting down the gain? I personally don't feel it is turned up too high now as it is cutting out at a moderate volumn - much lower than it will go and stay clear.

07-06-2009, 05:04 PM
Depends on the size of amps you are running. More powerful amps require bigger wire. Longer runs require bigger wire.

I ran 0 guage to my distribution blocks and then 4 guage to both amps. But both of my amps are pulling around 1000 watts. 2000 watts on a 4 guage wire over 10 feet is pushing it.

I love this site:


It has a wire size calculator as well in the section about wire.

07-06-2009, 05:21 PM
I will check the size wire I am running. My distribution block is not being used for the amp. I have one amp - Clarion 2 channel - 80x2.

Patrick Hardy
07-06-2009, 06:18 PM
Just to make sure you have a good ground, buy one of these and have all negative / ground wires terminate on it. http://www.productshipmarine.com/search.aspx?q=busbar
As for your wire size, how many batteries do you have? How long is the wire lengths? If you just have one battery and short wire lengths, then go with 4 gauge wires throughout.

07-06-2009, 07:53 PM
It might be obvious, but a busbar is not a ground unless one of the wires goes from the unit to the ground on the engine. Don't forget that wire;)

8 guage is going to be plenty big for a smaller amp like that.

Patrick Hardy
07-06-2009, 09:30 PM
Yeah, sorry my bad! I forgot the ground wire from the bus bar to the engine block or to the negative (-) wire/pole of your battery. I also recommend at least 4 gauge, because that leaves room for future stereo additions. Cheaper to wire it just once.

07-07-2009, 09:59 AM
should the negative on an auxilary battery go to a ground on the engine block?

Patrick Hardy
07-07-2009, 10:46 AM
The Negative Post on the auxiliary battery is a grounding location. Take your amp(s) ground wire and run it to this post. If you want to spend the money, then buy a longer wire and run it to the grounding bolt on your engine block. Either way you will have it grounded.

07-07-2009, 11:56 AM
i have a 1989 ps 190 - any idea where the negative ground is on the engine block?

07-07-2009, 03:06 PM
i have a 1989 ps 190 - any idea where the negative ground is on the engine block?

Follow the wire on the negative terminal on your battery and it will go right there. Most engines have them on both sides somewhere towards the front side of your engine before it is hooked to the tranny.

One possible worry is when you have a large stereo load and run big wires to the batteries, but the only ground is a smaller lead from the batteries to the engine. That can result in inadequate grounding. So make sure the lead to the engine ground is big enough for your system.