Grounding question

[Dafaseles]

This is my first post in this forum, hello everyone! Hoping for a little help.
I'm worried about if my grounding is going to be legit. I'm going to be installing 2 Sundown Salt 4's (using dual 1/0 to single 1/0 reducers), 1 cresendo S4, and 2 JL JX100.4's running if a Limitless Cyber 12k. What I was thinking was running 6 1/0 grounds (4 from the amps, 2 from the battery), and 3 4 awg grounds to a solid distribution block, then 4 or 5 runs of the knukoncepts 4/0 cable to a plate welded to the frame.
How does this sound to you all? I'm worried because, I know it's not the absolute rule, but I've always been told to keep my ground under 18". There's no way I can think of to keep my grounds under 18". The amps will be mounted under the box in the bed of my truck. Any info/ feedback would be greatly appreciated. Thanks in advance

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[jt4x4]

I personally have never understood why shorter grounds are recommended. Especially since some insist on running your ground all the way back to the battery.

 

[Dafaseles]

I personally have never understood why shorter grounds are recommended. Especially since some insist on running your ground all the way back to the battery.

I don't know either to be honest. It's just one of those things that I've always been told, but have never been in a situation to test out myself, so you just tend to take it as the gospel so to speak.
I also read about grounding back to the alternator bracket. There's no way people that do that have grounds shorter than 18". I've read that you want your ground path no longer than your power path and I think the ground path ends at the alternator bracket, though I might have misread that completely.
This being my first "big" build, I'm just trying to learn as much as possible so I do it right the first time.

 

[SlugButter]

I’ve always went by the short ground rule also. I’be always just assumed that the longer the wire, the more resistance it naturally has.

 

[nate0]

I run equal amount of ground cable or more if possible. If I have 2 runs of pos 2/0 from my alternator to my cells I run two 2/0 grounds from that circuit, usually one to the front frame from the alternator and one off the battery hookup both 2/0. If I have 2 2/0 runs from an amp, I run 2 2/0 ground runs from my amp to the cell, and 2 2/0 runs from the cell to the frame.

 

[Dafaseles]

I’ve always went by the short ground rule also. I’be always just assumed that the longer the wire, the more resistance it naturally has.

That makes sense. I'm going to try to make mine as short as possible, but their most likely going to be over 3 feet from the amps

 

[Dafaseles]

I run equal amount of ground cable or more if possible. If I have 2 runs of pos 2/0 from my alternator to my cells I run two 2/0 grounds from that circuit, usually one to the front frame from the alternator and one off the battery hookup both 2/0. If I have 2 2/0 runs from an amp, I run 2 2/0 ground runs from my amp to the cell, and 2 2/0 runs from the cell to the frame.

So you ground everything to the battery? Then the battery to the frame? My battery will be in the bed of the truck with the amps, but I won't have enough space to ground all 5 amps to the battery first unfortunately. As far as as many grounds as positives, I've always used that rule as well. I was thinking the 4/0 wire would be good for 1 and a half 1/0 wire. If I put the amps and the battery grounds to a distribution block, then used the 4/0 to the frame, I was thinking that'll take out from 9 grounding points down to 5, just kind of making it easier to deal with I guess. Does that sound like a logical idea? Or a bad idea do you think?

 

[nate0]

So you ground everything to the battery? Then the battery to the frame? My battery will be in the bed of the truck with the amps, but I won't have enough space to ground all 5 amps to the battery first unfortunately. As far as as many grounds as positives, I've always used that rule as well. I was thinking the 4/0 wire would be good for 1 and a half 1/0 wire. If I put the amps and the battery grounds to a distribution block, then used the 4/0 to the frame, I was thinking that'll take out from 9 grounding points down to 5, just kind of making it easier to deal with I guess. Does that sound like a logical idea? Or a bad idea do you think?

Yes. I ground to my battery because it is going to have multiple spots too, like a bus and easily accessible. In the back and because I built a buss bar for the battery yes all my grounds hit the battery buss first. If you have separate bus bars you can ground there then to the battery then frame, either way it is the same thing. The main thing is having equal grounds capacity for your positive runs. The current needs ample room to roam, length is not always a factor unless you just do like one ground or just are limited due to some other reason, and need a short stubby. It take the path of least resistance, and even if you have like huge 4/0 and 4 runs at like 5-8ft I doubt you will have issues with heat due to ground. You could have a short stubby ground but the place you choose to ground it could be poor...

Try whatever it is you want to do, you will know if there comes an issue due to grounding.

 

[nate0]

The main thing is complete the circuit and match the capacity of your total amperage draw. If your battery is capable of dumping 700-1000 amps in a single shot and you want that available for your amps, then beef up all runs to handle that load if possible. The battery reserve may not perform if you leave it out of the loop. Just like your front stock battery has 1 positive main and one negative main for like around 80-100amps, you would do the same for your reserve battery, where having 5 amps each with their own grounds then you should match that weight in positive feeds obviously then with negative run capacity to the frame from the battery.

This is one main reason I hate running multiple amps. I have stuck with 2 amps for the longest time and probably will just do 2 amps until I am forced to run a third, because it becomes a spaghetti of welding cable all over the place...

 

[Sierra Nate]

I think the reason you hear about the short ground wire rule is more related to the fact that there is always a good location for a ground within 18 inches of where you need it. Wire will inherently have resistance. The bigger the wire the less resistance per foot of wire. Shorter lengths have less resistance than longer. If you go Longe then you also need to go bigger in order to keep resistance equal. Your not going to get a bigger ground wire than your frame in most cases. Even a unibody has less resistance than a 30 foot long piece of 0 awg wire. Properly grounded to the chassis is always going to be the best ground...unless you can run a short 0 wag to the negative post. If your ground is over 18 inches then grounding to the chassis is probably better.

All that said...there are plenty of ways to run a proper ground more that 18 inches.

 

[Dafaseles]

I think the reason you hear about the short ground wire rule is more related to the fact that there is always a good location for a ground within 18 inches of where you need it. Wire will inherently have resistance. The bigger the wire the less resistance per foot of wire. Shorter lengths have less resistance than longer. If you go Longe then you also need to go bigger in order to keep resistance equal. Your not going to get a bigger ground wire than your frame in most cases. Even a unibody has less resistance than a 30 foot long piece of 0 awg wire. Properly grounded to the chassis is always going to be the best ground...unless you can run a short 0 wag to the negative post. If your ground is over 18 inches then grounding to the chassis is probably better.

All that said...there are plenty of ways to run a proper ground more that 18 inches.

I kind of get what your saying. Everything is going to be in the bed of my truck. Amplifiers mounted to a board under the box. Battery mounted behind the box so I can access the terminals if I need to. Not being a unibody truck, would grounding to the frame with a distribution block to big cable be better even though the runs will be longer? Or would it be better if I just ground to the floor of the bed of the truck with the cable coming out of the amplifiers? I've never grounded anything to the bed of a truck before. I don't know if it's different than inside the cab. Sorry if I sound like an idiot, just trying to get as much information from people who know more than me as I can