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What amp rating is 8 Gauge wire?


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#1 Viper

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Posted 21 November 2009 - 10:49 PM

Hey guys, just a quick one... what amp rating is gauge 8 wire/cable??

#2 ls2lxhatch

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Posted 22 November 2009 - 12:37 AM

8 gauge is 3 mm which is rated by Narva to 10 amps.

#3 Viper

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Posted 22 November 2009 - 01:09 AM

Are you sure? its supposed to be my main power feed from the battery to the main fuse for the loom and the fuse is 70amp...

#4 TerrA LX

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Posted 22 November 2009 - 06:40 AM

8 gauge is 3 mm which is rated by Narva to 10 amps.


The current rating is listed based on permissible voltage drop and not conductor heating.

The ability of a wire to carry a given amount of current is affected by a number of additional factors, which is not included in the AWG table. Temperature of the surrounding air, wire insulation, and number of other wires bundled together.

#5 76lxhatch

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Posted 22 November 2009 - 07:25 AM

Constant rating and what the current may surge to in an instant are way different and your fuse has to deal with the latter

#6 Bomber Watson

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Posted 22 November 2009 - 09:56 AM

8 guage is a waste of time to run from the boot (i assume this is what your doing)

0 guage is the go.

Go to a welder supply place and buy the 0 guage earth cables for the big welders, most good shops should have it on a roll for about $5-6 a meter, cheep is bro and the big welders run 300+ amps through it :D.

Edit, while i think about it and after re reading a bit, how long is this cable going to be??? Main fuse should be a maximum of 200mm from the battery....

cheers.

Edited by Bomber Watson, 22 November 2009 - 09:57 AM.


#7 Viper

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Posted 22 November 2009 - 11:47 AM

Nah isnt the main feed from the battery...

Battery is in the boot and a BIG cable runs from that under the car to the starter motor. then from the starter motor it says to run a 8 gauge wire to the "maxi-fuse" which is a 70amp fuse and from there a 8 gauge wire to the fuse box which everything runs off.

#8 JadeGreenLHSLR

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Posted 22 November 2009 - 12:50 PM

With electric wires the yanks use guage, auto uses mm and us electricians use mm2 which is the cross sectional aera of the copper.
Catalogues with give u different values, but heres some basic ones.

3mm automotive wire is 1.13mm2 and rated to 10 amp

4mm automotive wire is 1.84mm2 and rated to 15 amp

5mm automotive wire is 2.9mm2 and rated to 25 amp

6mm automotive wire is 4.59mm2 and rated to 50 amp

now if you are using cables that electricians use they will come it sizes that dnt directly match the auto sizes, these are the standard sizes we use.

1mm2 is 10 amps.

1.5mm2 is 15 amps

2.5mm2 is 20 amps and so on.

Extra to this there is allowances that work on how much heat is produced by the cable and how much heat it can disapate due to the inmediate surroundings of the wire acting like a blanket. The bigger the cable for the same amount of amps means less heat due to less resistance of the wire. If your still with me this means if you want 10 amps you run 1mm2, but its at its limit and if the cable is run in a bunch or where its not free to air it will get hot. So now you jack the cable up to the next size, 1.5mm2. and you get cable capable of carrying an 5 extra amps which means less resistance which equals less heat generated. much like a smaller light bulb putts out less heat and light.
So if you over compensate one size on your judgement you should be right. When running battery leads from the boot and such, consult the Aust standards on current carring standards or talk to ur cable dealer, they should want to know how many amps you require, length, volts and surrounds of route, under carpet, etc. But they should be rather large and ul probably be after big welding flex. thats just a bit of what i know, google is also good because a lot of diy ppl talk about what they have done n if it works.
Hope that is understandable.
Waz

#9 Bomber Watson

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Posted 23 November 2009 - 09:46 PM

Thanks for that JadeGreenLHSLR

Nah isnt the main feed from the battery...

Battery is in the boot and a BIG cable runs from that under the car to the starter motor. then from the starter motor it says to run a 8 gauge wire to the "maxi-fuse" which is a 70amp fuse and from there a 8 gauge wire to the fuse box which everything runs off.


Ok, in that case, yeah 8ga will do so long as your only running the standard stuff off it.

Cheers.

#10 Viper

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Posted 23 November 2009 - 09:59 PM

Ahuh... But still what amp rating is 8 gauge??? I have some 6mm cable which is rated at 50amps so wondering if thats enough?

#11 _torbirdie_

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Posted 25 November 2009 - 09:22 PM

Ahuh... But still what amp rating is 8 gauge??? I have some 6mm cable which is rated at 50amps so wondering if thats enough?


lol, reading the thread I share your fustration.

8 gauge is listed as ~70amps for chassis wiring, see: http://www.powerstre.../Wire_Size.htm.

In terms of voltage drop, what are you running that will be absolutely is critical that you get the full 12.6V without the engine running? regardless it aint going to matter much 1.5 metres of 8gauge is only going to create a voltage drop of ~0.2V at 70A.

#12 Viper

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Posted 26 November 2009 - 07:57 AM

Haha yay, cheers mate... Seems like I made a mistake putting the 50amp wire in then... Ill swap it for 8gauge then just to be safe :)

#13 _torbirdie_

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Posted 28 November 2009 - 04:16 PM

Haha yay, cheers mate... Seems like I made a mistake putting the 50amp wire in then... Ill swap it for 8gauge then just to be safe :)


You mentioned the 50 amp wire was 6mm?, but what was the diameter of the conductor itself?-that's the really the only thing that counts for current carrying

Edited by torbirdie, 28 November 2009 - 04:17 PM.


#14 Viper

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Posted 28 November 2009 - 05:46 PM

Not sure if their "6mm" wire is the OD or the Wire Diameter... but it says its rated at 50amp.

#15 SS Hatchback

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Posted 29 November 2009 - 11:38 AM

Not sure if their "6mm" wire is the OD or the Wire Diameter... but it says its rated at 50amp.


If its good for 50amps then i would says its closer to the 6mm2, because 6mm (OD)cable is good for over 100amps more like in between 2 or 3 gauge wire that cable size.
.

Edited by SS Hatchback, 29 November 2009 - 11:39 AM.





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