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Old 10-20-2013, 07:49 PM   #1
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Wiring a fuse block

Do I have to wire the fuse block to the battery ground or is the tub ground good enough? If I must ground to battery, whats the thinnest gauge i can go. I will be running 2 ga power. Thanks!

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Old 10-20-2013, 09:12 PM   #2
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If you running 2 gauge wiring to the fuse block, you must be planning to run some fairly high current circuits off of the fuse block. I would recommend running a ground return to the battery. If you require 2 gauge for the positive side, you will need 2 gauge for the return.

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Old 10-20-2013, 10:13 PM   #3
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I think its okay to run the ground to the tub if it is a bare metal connection. You just need to remove the paint at that area. This is the way my Alpine PDX-V9 amp was professionally installed. It does use the same size wire as the power wire which is wired directly to the battery with an in-line fuse. The amp power cable is huge, the same size as my battery cable. Those cables are super expensive. No sense in wasting that much money unnecessarily.
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Old 10-21-2013, 07:02 AM   #4
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I have a flat amp/speaker that is currently using 6ga, I also plan to run 3 pairs of lights, my CB, and internal LEDs currently. I bought the 12 line fuse block in case I decide to run more acc. The amp/speaker uses a 6 so i figured better safe than sorry by getting the 2ga. My battery looks like a rats nest, so that is why I bought the fuse block. The amp wiring kit I bought has ground to the tub. I read that you ground to battery because on a boat, there is no real other good place to ground as boats are fiberglass. Thanks for the advice all.
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Old 10-21-2013, 11:44 AM   #5
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Yes, you can just ground to the tub.... BUT!!!!! .... There must be a path for the energy to return to the battery. The frame / tub / block gives no actual ground, only a path back to it via the ground straps connected to the neg terminals. This is why simply disconnecting the negative lead from a battery de-energizes the entire vehicle.

Think of it like this... The intake on your jeep is positive, the exhaust negative. Regardless of how powerful our engine is, those two need to be properly matched - same with grounds. You couldn't use a 4" intake pipe and 1" exhaust and expect good 'power', for instance.

If you do go to the tub, make sure your ground strap from tub to batt grnd is 2ga as well.
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Old 10-24-2013, 03:10 PM   #6
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It actually comes out of the tub and flows into the positive.
Think most of the wires that are installed (mon$ter) are overrated and priced aren't they.
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Old 10-24-2013, 08:26 PM   #7
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A true 2 awg wire is rated to 200 amps (1200 watts) on a 25' run... There is almost no way all the equipment you plan to add is going to even come near that. Cut the length down on the run (you shouldn't need more than 12-18 ft to reach from the battery to the back) and you increase the current capacity of the wire; that makes 2 gauge overkill, and a waste of money, IMO.

Add up all the fuse sizes for the items you plan to run. My guess is that you will be around 100 amps. I would not run any individual item through the fuse block if it is fused above 40 amps. It's a better idea to leave the audio amp's dedicated battery and ground paths than it is to run them through your fuse block - excessive current on any of the individual current paths will most certainly start melting things. Depending on how long your run is and how much current your devices will consume, I would guess that 6 or 4 awg wire would be more cost effective and still allow for additional components to be added later on.

If you do find that your total current consumption does actually require the use of 2 awg wire, than you have a bit more work in front of you. Your factory battery cables and ground paths are 8 gauge at best; this means you will need to upgrade the factory battery to ground, alternator to battery, and engine block to frame cables. Since the factory was 8 awg and you added 2 awg, your looking at 1/0 awg cables here to properly free up your ground and charging paths. Next, you'll find that the stock alternator only puts out 90 amps continuous at best. A custom built, high output alternator is in your future, as your stock one struggles to keep up with the constant demand.

It's your money, but unless you really need it, and are prepared to spend the extra coin to do it right, it really is just a waste of money.


To answer your original question, I would also need to know where you are mounting the fuse block. If it's in the engine bay, I would battery or frame terminate the ground path. If you are in the tub, I would really consider running it out under the tub and frame grounding it, as long as the run doesn't have to be too long. If you can't do that, than a good solid panel of the tub will work - just be sure all the paint is scraped away and that it's not a piece of thin metal that's just tack welded to the actual tub. Generally speaking, it's best to keep the return paths as short as possible, so terminate the ground as close to the fuse block as possible, while still keeping the above in mind.
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Old 10-24-2013, 08:41 PM   #8
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Quote:
Originally Posted by dr_jenkem View Post
It actually comes out of the tub and flows into the positive.
Not really. In a DC circuit (direct current, ie battery power) the current flows from the positive to the negative, following the path of least resistance. When a device is installed, it completes a circuit and the current flows from the positive pole into the device, then flows out of the device and into the negative pole of the voltage supply. By grounding a device, you are supplying a return path for the current through the frame of your vehicle and then back to the battery through it's ground path. This is why, as BlueRidgeYJ already explained, you need equally sized cables on the positive and negative connections.

Quote:
Think most of the wires that are installed (mon$ter) are overrated and priced aren't they.
If you are comparing Monster's 4 awg to Wal-Mart's "4 gauge" than yes, it is over priced. The problem is, the Wal-Mart kit uses the term "gauge" instead of "AWG" or "American Wire Gauge" which is actually standardized. Gauge means they can use a 14 awg worth of actual copper and then just wrap it with 4 awg sized insulation. Compare the "4 gauge" kit to Monster's 14 AWG kit, and I think you will see an alignment of costs. Copper isn't cheap, so of course a true 4 awg wire will cost more than a fake 4 awg.
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Old 10-25-2013, 05:57 AM   #9
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Actually I got a 4ga amp kit, not 2ga. This is the kit I bought. http://www.amazon.com/gp/aw/d/B00AFL...f=ya_aw_oh_pit
You do make sense to leave the amp direct to battery. I plan to put it right inside past the fire wall now that you suggest not removing the amp wires. What I will be running to it is:
1. Fog lights stock, 2
2. Led lights 2
3. Rugged ridge lights 55 watt 2
4. CB
5. Interior led light strips total of 6 on control box

These are what I currently have to add to the block. With the shorter distance, i should be able to use the same wire and run 1/2 of it to power and 1/2 to neg battery. Any input on what size fuses to use in each?

Thank you all again, I sure dont want to melt anything
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Old 10-25-2013, 09:29 AM   #10
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Actually, so called conventional current flow is from positive post to negative post. In reality, electron current flow is from the negative post to the positive post as the negative has an excess of electrons that are attracted to the more positive electron deficiency of the positive terminal..
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Old 10-25-2013, 09:35 AM   #11
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Oh, and for the fuses, watts law says Power(watts)=Current(amps) x Voltage (volt). Example, 55watts ÷ 14.4volts = 3.8 amps...so one of the 55w bulbs should have probably a 5 amp fuse.
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Old 10-25-2013, 10:40 AM   #12
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Quote:
Originally Posted by I-Want-A-Jeep View Post
Oh, and for the fuses, watts law says Power(watts)=Current(amps) x Voltage (volt). Example, 55watts ÷ 14.4volts = 3.8 amps...so one of the 55w bulbs should have probably a 5 amp fuse.
Thanks

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