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Reducing 4ga to 8ga

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=55940
Printed Date: March 28, 2024 at 7:55 PM


Topic: Reducing 4ga to 8ga

Posted By: 704acc
Subject: Reducing 4ga to 8ga
Date Posted: May 17, 2005 at 9:42 PM

My alpine MRV-F450 accepts an 8 guage power wire.  I want to run a 4 guage power wire then reduce it to fit the 8 guage connection.   Any suggestions on how to do this and where I might find such a connector? {other than the local audio stores}

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Ray Kane



Replies:

Posted By: stevdart
Date Posted: May 17, 2005 at 9:49 PM
The accepted way is to use a fused distribution block that will accept 4 ga. in and has at least one 8 ga. out.  The distro has a slot for the fuse that will be necessary for the smaller 8 ga. wire.  Any other method you use for connecting a larger to a smaller power wire must include a fuse at the power supply end of the smaller wire.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: 704acc
Date Posted: May 17, 2005 at 9:55 PM

Thanks for your prompt response.

I am only using one amp, so I do not need a distribution block.  I am going to have a fuse or circuit breaker on the 4 guage wire about 10 inches away from the battery.  From there I will run directly to the amp under my seat.  At the amp end is where I have to reduce the wire size.



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Ray Kane




Posted By: stevdart
Date Posted: May 17, 2005 at 10:09 PM

stevdart wrote:

Any other method you use for connecting a larger to a smaller power wire must include a fuse at the power supply end of the smaller wire.

...which is why I wrote what I did.  The power supply end of the smaller wire would be where it connects with the 4 ga.  But another way to accomplish what you want is to simply clip outer wire strands on the 4 ga. until you reduce it to the point where it will fit the amp input.  No additional wire fuse would be needed this way.



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: 704acc
Date Posted: May 17, 2005 at 10:15 PM

So I should have a second fuse down stream from the one at the car battery since I am reducing the wire size?

Am I causing a hazard if I were to clip down the 4 guage wire at the amp like you said?



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Ray Kane




Posted By: RedKatanaX9
Date Posted: May 17, 2005 at 11:01 PM
If you are only running one amp, why would you want to run 4 gauge and reduce it to 8 gauge? All you need to do is run the 8 gauge from battery to amp.

Unless you plan to expand your system to have multiple amps later, then it makes sense to run 4 gauge now, but you should still use a distribution block, then 8 gauge out to your amp.




Posted By: 704acc
Date Posted: May 18, 2005 at 12:15 AM
The amp is a 5 channel setup @ 50x4 + 200x1  A lot of current for an 8 guage connection.  It is in a pickup truck and there will not be any other amps added.  I do not want to use a distribution block unless I have to.

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Ray Kane




Posted By: jeffchilcott
Date Posted: May 18, 2005 at 1:08 AM
distro blocks, cheaps ones are like $10 at wal-mart

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place




Posted By: TruckSystem
Date Posted: May 18, 2005 at 8:19 AM
Just clip off strands till it fits an 8 guage connector, no need for a distro block in that setup imo.

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2003 Chevrolet Silverado Standard Cab ~ Alpine CDA-9851
Diamond Audio D3600.1 ~ 2x Diamond Audio TM310D4
Diamond Audio D3400.4 ~ Diamond Audio Hex S600s
AstroStart RS5204 Remote Start/Alarm




Posted By: jcassonjr
Date Posted: May 18, 2005 at 10:29 AM
an 8 ga power source in an application like that should be fine. A chain is only as strong as its weakest link.

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Alpine cda-9855
Alpine Mrd-m1000
1 farad digital Rockford cap
2 Treo SSi 12's
Large centerport box




Posted By: RedKatanaX9
Date Posted: May 18, 2005 at 12:15 PM
8 gauge is more than adequate for amp that size. If you use 4 gauge and reduce/clip wires off so it will fit an 8 gauge connector, all the current floowing on the 4 gauge part will HAVE to go through the 8 gauge part, like Jcnssjr said, a chain is only as strong as its weakest link.




Posted By: glamisguy99
Date Posted: May 18, 2005 at 4:52 PM
That amp sounds like it was designed to power an entire system, not necessarily be part of a multi-amp setup.  With this being the case, if the manufacturer deemed it necessary to run 4 ga. power wire it would have included a 4 ga input.  If theres an 8 ga input this should suffice for the entire power line.  You trusted the manufacturer to build a quality component to put in your system, trust this too.




Posted By: jussam
Date Posted: May 22, 2005 at 8:19 PM

this will give you a cleaner look than shaving the wire

https://www.cardomain.com/item/LITRA48

posted_image





Posted By: the4biddendonut
Date Posted: May 27, 2005 at 10:33 PM

shaving the wire is ghetto if your asking me, but if you must try soldering the end up before sticking it in the 8 awg connector. 

one thing to keep in mind is, the reason you would want to run a bigger awg conductor is to carry more current.  when there is too much current, the wire produces heat, which translates to lost power disipated by heat.  if you did run 4 awg and then ran 8 awg to the amp, you'd better off than just running the 8 awg the whole way because the 8 awg section would be the weak link that is disipating the heat. 

my opinion is to just run 8 awg because you shouldn't be drawing that much current.



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I hope life isn't a big joke, because I don't get it. - Jack Handy




Posted By: samroza
Date Posted: May 28, 2005 at 2:33 AM

RedKatanaX9 wrote:

If you are only running one amp, why would you want to run 4 gauge and reduce it to 8 gauge? All you need to do is run the 8 gauge from battery to amp.

Unless you plan to expand your system to have multiple amps later, then it makes sense to run 4 gauge now, but you should still use a distribution block, then 8 gauge out to your amp.

Ding ding ding. If you reduce the size of the wire at your amp, you are effectively wrecking any advantage you gained by using 4ga wire from the battery. Heat, inefficiency, Etc could be the result.

Just run 8ga wire. cheaper, easier, no fiddling with cuttin gthe diameter of the wire down.

Sam



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Sam Roza




Posted By: the4biddendonut
Date Posted: May 28, 2005 at 11:44 AM

running a 4 awg, then switching to to an 8 awg would give you a little advantage over just running an 8 awg the whole way. here's why.

you'd have an advantage because the short 10 inch length of the 8 awg would be the only part dissipating heat, rather than having the whole 10-12 feet of 8 awg dissipating heat, which is lost power.  heat is the product of resistance in a conductor because the heat given off is due to a purely resistive load on the cable.  8 awg has a higher resistance than 4 awg.  it's not that hard to figure out that the 4 and 8 awg combination will have less resistance than the just straight 8 awg.  just make sure your connections are good,  i would use a distribution block.  for example a visegrip crimp is not a good connection, they pull apart every time.

it's not a huge advantage we're talking about here, but there is an advantage.  plus it gives you the option to go bigger later.



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I hope life isn't a big joke, because I don't get it. - Jack Handy




Posted By: audiocableguy
Date Posted: May 29, 2005 at 9:40 AM
Voltage drop is just as important as amperage. The higher the voltage you can get to amp the better.

Example: the following info is based on a 3% voltage loss chart from Wrangler Power Products for a 14.5 VDC system

50 amps @ 3 feet = 10 AWG
50 amps @ 10 feet = 8 AWG.
50 amps @ 25 feet = 6 AWG
50 amps @ 40 feet = 4 AWG

The amperage remains constant. The changing distance is what is adding the resistance. The larger wire would reduce voltage drop over that distance.

According to the chart, 8 AWG would be ok for a run of 10 to 12 feet @ 50 Amps. Personally I would run 6 AWG since it is good for 25 feet with less than 3% voltage drop..




Posted By: the4biddendonut
Date Posted: May 29, 2005 at 11:29 PM

is there a formula for figuring out voltage drop that you know of?  i know this one for figuring out the drop of conductors that are used for building construction.

voltage drop = (2 x K x L x I) / KcMil

where K is a constant resistance.  L is the length, and I is the load.  kcMil is the circular mil area.

the problem is that i don't know how the construction of conductors for building and for car audio differ.  does anyone know if this formula will work or not???



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I hope life isn't a big joke, because I don't get it. - Jack Handy




Posted By: stevdart
Date Posted: May 30, 2005 at 1:14 AM
I don't know what formula this calculator uses, but you might be able to check your formula against the answers given.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.





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