Power and Ground Wire Size

[LT206]

I figured out today that I'm going to have about 16 feet from my battery to my distribution block. I'm using 1/0 power and ground wire. I was planning on running the ground back to the battery (for shorter distance) but I noticed that the negative battery cable which goes back to ground at the engine block near the starter is 2 ga. wire. Is this smaller wire between the battery and ground at the engine block going to cause me problems if I stop my amp ground at the battery? Or should I just run the amp grounds all the way back to the engine block? This makes it like a 22 foot run of ground wire.

Or maybe I'm totally misunderstanding the ground system on a boat - any ideas would be appreciated....

[Mikeski]

RE: Power and Ground Wire Size

Basically your stereo will be running off the battery and your alternator will be charging the battery. So your block to battery wiring only needs to be sized for your alternator and brief starting load. The main reason for the large gauge of the stereo leads is to eliminate the voltage drop over the 16' run. Run the 1/0 up to a distribution block and run the entire audio system off this block including the head unit. You can run a switched lead off the boat harness if you must have a keyed source, I prefer a dedicated accessory switch that is also sourced off the distro block.

[LT206]

RE: Power and Ground Wire Size

Ok, that solves the ground location.

including the head unit, hmm.. why do you need to do that? why can't you just run the head unit off the factory harness? since the amps inside the head unit aren't hooked to anything the only power it needs is to power on and send a signal to the amps. tell me more...

I was going to use the remote turn on lead (blue and white wire on the xmd1) from the head unit to the amps to tell the amps when to turn on, but I hadn't thought about running the head unit off the dblock too. Is that what most folks are doing?

[LT206]

RE: Power and Ground Wire Size

remote turn on lead (blue and white wire on the xmd1)

Edit - the remote turn on for the XMD1 is the solid blue wire - not the blue and white wire (that's the antenna turn on wire)

[mgswed]

RE: Power and Ground Wire Size

Why dont you just ground it at the negative side of the battery? Run your positive to your distribution block (Dont forget the fuse by the battery), then run power wire at whatever guage the amps need from the distrib block (dont forget the correct fuses after the distrib block). Then ground everything to another distrib block and 0/1 back to the battery. -MG

[LT206]

RE: Power and Ground Wire Size

Why dont you just ground it at the negative side of the battery? Run your positive to your distribution block (Dont forget the fuse by the battery), then run power wire at whatever guage the amps need from the distrib block

That is exactly what I'm going to do. I was just wondering if I needed to add an additional 1/0 ground from the battery to the engine block, but it sounds like I don't.

Mikeski threw me a loop with powering the head unit off the distribution block because I hadn't thought about that, and I was wondering why that would be better than powering the head unit from the factory wiring harness.

Another thing I wasn't planning on doing was fusing the 1/0 supply wire at the battery, but I may need to reconsider that too.

[Mikeski]

grounding

Running the head unit off the factory harness is probably the most common mistake people make when they upgrade their systems. The unit will play but you will almost certainly have engine whine in your system. The cause is a difference in voltage potential between the deck's ground and the boat harness ground. If you take the extra time to do it right now your system will sound much better and be more trouble free in the long run. This also solves most other noise issues that depth finders, perfect pass, and other boat systems introduce into the audio system.

[mgswed]

RE: grounding

LT206, You definately want to put in a fuse as close to the battery as possible, also as close to the distrib block on any reduction in wire size (preferably the fuses held in place by the distrib block). If you don't you run the risk of a wire frying and possibly starting a fire. -MG

[Mikeski]

RE: grounding

Fusing the 1/0 is a debateable issue. You will notice that the factory does not fuse the starting lead. If the wire has the ability to carry the short circuit current then it does not necessarily require a fuse. My stereo system has the capability of pulling in excess of 100amps. If I ran a fuse on the main lead it would need to be over 100 amps. A 90amp short could definately cause a fire in my boat. So, I used good marine rated power wires, ran them carefully, and insulated them well at every connection point, with no fuse between the batteries and the distribution block. I believe this is how the factory would do it if they offered a high current power distribution system. This is an instance where boats are very different than cars.

A fuse will not protect you from potential issues that could arise from poor wiring practices.

[LT206]

RE: grounding

Mikeski - where did you find marine rated power wire - I ordered Stinger HPM 1/0 wire - oxygen free copper - don't know if it's tinned or not.

Really there are only two connections in the main power wire - at the battery and at the distribution block that the wire could get shorted.

I'm going to fuse it anyway - using a 250 amp fuse that way the wire can carry it's full load but will not fry if it shorts. I will never see a 250 amp load from my amps.

[Mikeski]

RE: grounding

Search this number on e-bay: Z290065539710 for marine pre tinned power wire, it's not cheap but it is the best stuff I have found.

Even with the 250 amp fuse, a partial short will not cause it to blow but will cause a fire. Do what makes you comfortable, use plenty of tie wraps, make sure there is slack at each end, use another foot or two of wire so you can run it out of harms way.

Good luck!

[brichart]

RE: grounding

I was just getting started with my "winter project" on my '95 SN. Adding a new amp. (total of two - 1 is 600w and the other is 150w), a new sub. and four new 6 in. (total 6). The existing amp. and head unit appear to be running from a spliced factory power wire and factory harness respectively. Obviously, from this discussion, the previous owner was "playing with fire," literally.

I need to know what your talking about with regard to 1/0 wire. I don't know what this is and if it's necessary. I would presume that running a hot wire and a ground directly from the battery is advisable. I don't know what to do from there. Some advice would be greatly appreciated.

Incidentally, with the head unit powered into the harness I have heard occasional engine noise, especially before the system warms up.

-Brian

[mgswed]

RE: grounding

0/1 wire is just the gauge of wire. It's a thick wire that allows for a lot of amps to be drawn through it. Some people say you should fuse any wire that comes from the battery, others say that with that thick of wire, the amount of power going through it isnt going to matter in regards to safety because you'll never draw enough for it to burn up. Typically you would run whatever guage necessary from the battery to a distribution block and then for every reduction of wire gauge you need run wires from the distrib block with fuses if the distrib block doesnt already contain them to the amps. Then run your grounds together (probably back to another distrib block) back to the negative side of the battery (some people choose the engine block). You head unit should be attached to switched power and the remote turn on wire should run to your amps. This way when you turn on the ignition breaker, power will go to the head unit and in turn, turn on your amps. For the gauges of wire check the install manual for each amp and the fuse sizes should be in there as well. For you main power and ground runs 0/1 will be good, maybe a little over kill. Someone else on here might be able to give you a better idea on what size wires to run. I just havent done it in a while and cant remember. -MG

[TRBenj]

Re: RE: grounding

This way when you turn on the ignition breaker, power will go to the head unit and in turn, turn on your amps.

I think he meant ignition key.

[brichart]

Actually, I understood the "ignition breaker" to mean the ignition button on the dash that initially powers the boat. My current stereo allows for play without the key activated provided the ignition button is depressed.

Thanks for the info. MG. I looked at the American Wire Guage guide and learned that 1/0 wire is 55 mm. Wow, overkill indeed. But I understand your point about not burning it up.

I will use the distribution block as suggested and probably 8 guage wire...unless my local electrician yells at me, because I'm only powering two smaller amplifiers. The setups I've seen involving the 1/0 wire seem to be powering two and sometimes three good size amplifiers.

I've seen some pictures in this forum of some incredibly complicated and impressive systems. Since I don't intend on sharing my music with the rest of the lake (at least that's what my wife says), I'm going more modest. But I think the Infinity equipment will sound nice.