Fordmods Logo

Wire Question 

 

Page 2 of 3 [ 35 posts ] Go to page Previous  1, 2, 3  Next

 
Posted: Mon Jul 30, 2007 8:26 am 
Tyre Shredder
Offline
User avatar

Age: 110

Posts: 379

Joined: 20th Aug 2006

Gallery: 3 images

Ride: BA Predator

Location: HERVEY BAY
QLD, Australia

outlawxr6 wrote:
Atz88, I think you need to check your electrical theory my friend

"an ova 3m u will get no detectabe current lose. the thicker the wire the more resistence it will have tho. "

Firstly, you don't lose current you lose voltage from effect of current and resistance.

Secondly, the thicker the cable the LESS resistance not more, otherwise there wouldn't be thicker cables if this was the case...

Thirdly, how can a larger cable create a noticably larger magnetic field? A magnetic field is directly related to the amount of current being passed through the cable...


thanks for the answers

i was planing on running the cable down the centre of the car so it would not affect any of the audio wires running already running along the sides

also the reason for spliting the wires in the first place was so it wouldnt leave a huge bulge in the carpet,

all the other cars ive done ive run 4g down the side (speaker's n" rca's down the other)

was going for something a little better this time
Top
 Profile  
 
 
Posted: Mon Jul 30, 2007 8:40 am 
Getting Side Ways
Offline
User avatar

Posts: 2945

Joined: 24th Jan 2005

Gallery: 18 images

Ride: XW, EL, Territory, VFR800

Power: 129 rwkw

Location: Adelaide
SA, Australia

Hey Shadow, I know the question has been answered but, check this website out, very helpful for any power wiring stuff... http://www.bcae1.com/wire.htm
Top
 Profile  
 
 
Posted: Tue Jul 31, 2007 12:27 am 
ACT Cruise Moderator
Offline
User avatar

Age: 36

Posts: 6275

Joined: 24th Nov 2004

Ride: '06 BF GT-P

Power: 293 rwkw

Location: Canberra
ACT, Australia

To answer the question about multiple cables. You need to find the resistance of each cable. For example (look up or measure the real values, I'm plucking values from thin air).

1x 0GA cable has a resistance of 0.001Ohm / Metre
1x 4GA cable has a resistance of 0.005Ohm / Metre

Say you have 5 metres of cable (as most of us with Falcons and a front battery would)

The 0GA will have a total resistance of 0.005Ohm, and the 4GA a total of 0.025Ohm.

Put 100A through each (4GA maxs out at about 140A, so we're keeping safe here). And starting with a healthy 13.8V battery on alternator charge at the far end we'll be left with....
0GA - 13.3V a loss of 50W of power into the cable (heating it).
4GA - 11.3V a loss of 250W of power into the cable (heating it alot)

Now for two 4GA runs in parallel. Resistance in parallel is the average of all runs. So 2x 4GA runs will have a resistance of 0.0025Ohms per metre. Again with a 5 metre (0.0125ohm total) distance from the front battery to the amp in back with a 13.8V alternator charge, we have....
2x 4GA - 12.55V a loss of 125W into the cables (heating them).

The more 4GA runs you add the closer you'll get to the 0GA, eventually beating it.

The hardcore SPL cars, have sometimes as much as 8 times the cable they need, to ensure voltage drop is a small as possible. I've seen a SPL car with 16 runs of 0GA!

Personally, I have a single 4GA power run, and a 2GA earth run powering ~1400WRMS of amps, and a 120A circuit breaker.

SPL guys don't run fuses or breakers as they add more resistance.

edit: IRL 0GA isn't 5 times better than 4GA, it's slightly less than 2 times better, so two runs of 4GA will out perform 1 run of 0GA.

 

_________________

1998 DL LTD in Sparkling Burgundy, daily, 302W, stereo, slow - 97.5rwkw
2006 BF GT-P in Ego, mods. 293rwkw - 12.427@109 - 0-1000m 24.838@221

Top
 Profile  
 
 
Posted: Tue Jul 31, 2007 12:41 am 
Tyre Shredder
Offline
User avatar

Age: 110

Posts: 379

Joined: 20th Aug 2006

Gallery: 3 images

Ride: BA Predator

Location: HERVEY BAY
QLD, Australia

Groovey,i will look into the resistance when getting my cables, and keep all that has been said in mind, however im not planning to go in any SPL comps any time soon.
Top
 Profile  
 
 
Posted: Tue Jul 31, 2007 1:24 am 
ACT Cruise Moderator
Offline
User avatar

Age: 36

Posts: 6275

Joined: 24th Nov 2004

Ride: '06 BF GT-P

Power: 293 rwkw

Location: Canberra
ACT, Australia

For most people, a single 4GA run will suffice. If you want the capacity of 0GA without the bulky cable, then two 4GA runs will do.

 

_________________

1998 DL LTD in Sparkling Burgundy, daily, 302W, stereo, slow - 97.5rwkw
2006 BF GT-P in Ego, mods. 293rwkw - 12.427@109 - 0-1000m 24.838@221

Top
 Profile  
 
 
Posted: Tue Jul 31, 2007 6:20 pm 
Stock as a Rock
Offline
User avatar

Age: 41

Posts: 180

Joined: 21st Jul 2005

Gallery: 4 images

Ride: FG XR6

Location: Geelong
VIC, Australia

Perfect answer data_mine.

 

_________________

Subtle but high quality audio system.
Alpine processor and amp / Focal Utopia splits / Soundstream Exact sub

Top
 Profile  
 
 
Posted: Fri Aug 03, 2007 10:09 pm 
Oompa Loompa
Offline

Age: 29

Posts: 46

Joined: 27th Dec 2006

Location: Wagga
NSW, Australia

a thicker cable carries more current true, the creation of a magnetic field is directly proportional to current which flows perpondicular to the cable.

the thicker the cable the more resistance u get because of the more electrons flowing through it consequently creating heat an resistance, obviously the resistance isn't great because its metal an won't even be noticable on multimeter but in acturley fact it does create a higher electro magnetic field an more resistance.

so maby u should get ur facts right buddy.

if you don't beleive me run a 20g wire next to ur rca's then compare it to a 0g wire... n hence is y u cross rca's at 90 degrees to the power cables if u must cross them..

 

_________________

Soon to be the finest Sounding BA Ute

Top
 Profile  
 
 
Posted: Fri Aug 03, 2007 10:52 pm 
Tyre Shredder
Offline
User avatar

Age: 110

Posts: 379

Joined: 20th Aug 2006

Gallery: 3 images

Ride: BA Predator

Location: HERVEY BAY
QLD, Australia

wouldnt a 20g be smaller? ie 8g is smaller than 4g & 4g smaller than 0g?
Top
 Profile  
 
 
Posted: Fri Aug 03, 2007 11:06 pm 
Stock as a Rock
Offline
User avatar

Age: 41

Posts: 180

Joined: 21st Jul 2005

Gallery: 4 images

Ride: FG XR6

Location: Geelong
VIC, Australia

You're wrong Atz88 - you may want to apologise

In simple terms:
A thicker cable doesn't mean more magnetic field - like you said yourself the magnetic field is caused by the current flowing through the cable.
The more current - the stronger magnetic field. The size of the cable doesn't have anything to do with it.
A thick cable can carry a small current too. The magnetic field would be small. If you have 10 Amps flowing through a thick cable it's the same magnetic field as a thin cable.

In advanced terms:
The formula to calculate magnetic field around a current carrying wire:
B = (µo I)/(2 pi r)
where
µo, permeability of free space = 4 pi x 10-7 Tm/A
I, current flowing through the wire, measured in amps
B, magnetic field strength, measured in Tesla
r, distance from the wire, measured in meters

So basically current (I) and distance away (r) are what determines the magnetic field at a point.



Source:
http://dev.physicslab.org/Document.aspx ... gWires.xml

 

_________________

Subtle but high quality audio system.
Alpine processor and amp / Focal Utopia splits / Soundstream Exact sub

Top
 Profile  
 
 
Posted: Fri Aug 03, 2007 11:23 pm 
Oompa Loompa
Offline

Age: 29

Posts: 46

Joined: 27th Dec 2006

Location: Wagga
NSW, Australia

yeh thats wot i ment 20g u will be able notice a large difference compared to 0g.

an with a battery of 550 coldcracking amps a cable of thicker size will induce more amps through it to a amp compared to a 20g wire.

 

_________________

Soon to be the finest Sounding BA Ute

Top
 Profile  
 
 
Posted: Fri Aug 03, 2007 11:48 pm 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 582

Joined: 20th Nov 2004

Ride: xr6

Location: Brisbane
QLD, Australia

Hmmm I think we have a serious short coming in ohms law here Atz88

"the thicker the cable the more resistance u get because of the more electrons flowing through it consequently creating heat an resistance, obviously the resistance isn't great because its metal an won't even be noticable on multimeter but in acturley fact it does create a higher electro magnetic field an more resistance.

so maby u should get ur facts right buddy. "

Where did you get this load of dribble from as it is certainly not based on any from of electrical theory.
If a thicker cable has more resistance then it would NOT be able to carry more current as it would generate more heat and the voltage drop would be higher as well defeating the point.

So maybe you should check some electrical theory and use some actual facts before sprouting garbage like this.......
The more area of copper he lower the resistance full stop!!!!!!!!!!

 

_________________

Do it once, Do it right!!!!!!

Top
 Profile  
 
 
Posted: Sat Aug 04, 2007 12:16 am 
ACT Cruise Moderator
Offline
User avatar

Age: 36

Posts: 6275

Joined: 24th Nov 2004

Ride: '06 BF GT-P

Power: 293 rwkw

Location: Canberra
ACT, Australia

^ bingo.

bigger cable is good for everything (less resistance, more current flow, less voltage drop). The amount of magnetic field generated has nothing to do with the thickness of the cable, only how much current is flowing (true you can get more current down a thicker cable, but it's the more current making a bigger field, not the bigger cable).

I've already posted the essential maths required.

 

_________________

1998 DL LTD in Sparkling Burgundy, daily, 302W, stereo, slow - 97.5rwkw
2006 BF GT-P in Ego, mods. 293rwkw - 12.427@109 - 0-1000m 24.838@221

Top
 Profile  
 
 
Posted: Sat Aug 04, 2007 12:31 am 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 582

Joined: 20th Nov 2004

Ride: xr6

Location: Brisbane
QLD, Australia

Exactly as I said earlier.....

I don't know where some people come up with this rubbish....

 

_________________

Do it once, Do it right!!!!!!

Top
 Profile  
 
 
Posted: Sat Aug 04, 2007 12:40 am 
Tyre Shredder
Offline
User avatar

Age: 110

Posts: 379

Joined: 20th Aug 2006

Gallery: 3 images

Ride: BA Predator

Location: HERVEY BAY
QLD, Australia

data_mine wrote:
For most people, a single 4GA run will suffice. If you want the capacity of 0GA without the bulky cable, then two 4GA runs will do.


sounds like the go to me thanx data_mine
Top
 Profile  
 
 
Posted: Sat Aug 04, 2007 1:45 am 
Oompa Loompa
Offline

Age: 29

Posts: 46

Joined: 27th Dec 2006

Location: Wagga
NSW, Australia

lol buddy im tellin u a thicker cable gives more resistance to electrons because there are more atoms in the cable they hit each other an create more heat an resistance this has nothing to do with ohms law, this is how u get resitance over km's of cable because there are more electrons flowing thus creating more atom collisions in lamins terms.

hence y i said the resistance isn't measurable in a simple 3m setup, its apon km's of cable u get resistance. an electro magnetic field generated is directly proportional to the current passing through it.

 

_________________

Soon to be the finest Sounding BA Ute

Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 2 of 3  [ 35 posts ]  Go to page Previous  1, 2, 3  Next

Who is online

Users browsing this forum: No registered users and 10 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

 

 

It is currently Thu Dec 14, 2017 12:23 pm All times are UTC + 11 hours

 

 

(c)2014 Total Web Solutions Australia - Australian Web Hosting and Domain Names