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Reducing 4ga to 8ga

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Member - Posts: 10
Member spacespace
Joined: May 13, 2005
Location: United States
Posted: May 18, 2005 at 12:15 PM / IP Logged  
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.
Member - Posts: 32
Member spacespace
Joined: April 21, 2005
Posted: May 18, 2005 at 4:52 PM / IP Logged  
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.
Copper - Posts: 78
Copper spacespace
Joined: June 03, 2004
Location: United States
Posted: May 22, 2005 at 8:19 PM / IP Logged  

this will give you a cleaner look than shaving the wire

Reducing 4ga to 8ga - Page 2 - Last Post -- posted image.

Member - Posts: 23
Member spacespace
Joined: April 10, 2005
Location: United States
Posted: May 27, 2005 at 10:33 PM / IP Logged  

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.

I hope life isn't a big joke, because I don't get it. - Jack Handy
Member - Posts: 43
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Joined: May 27, 2005
Location: United States
Posted: May 28, 2005 at 2:33 AM / IP Logged  

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 Roza
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Joined: April 10, 2005
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Posted: May 28, 2005 at 11:44 AM / IP Logged  

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.

I hope life isn't a big joke, because I don't get it. - Jack Handy
Copper - Posts: 630
Copper spacespace
Joined: January 27, 2003
Location: Idaho, United States
Posted: May 29, 2005 at 9:40 AM / IP Logged  
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..
Member - Posts: 23
Member spacespace
Joined: April 10, 2005
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Posted: May 29, 2005 at 11:29 PM / IP Logged  

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???

I hope life isn't a big joke, because I don't get it. - Jack Handy
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Posted: May 30, 2005 at 1:14 AM / IP Logged  
I don't know what formula this calculator uses, but you might be able to check your formula against the answers given.
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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