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amp wiring laws and why to go bigger?


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boostedkreation 
Member - Posts: 2
Member spacespace
Joined: March 09, 2010
Location: Indiana, United States
Posted: March 09, 2010 at 10:56 AM / IP Logged  
ok here is the deal. I am trying to explain to my boss as to why when you run bigger amps or multiple amps why 4 gauge wiring will or will not work. we recently did a install in a 94 camaro. We installed 2 12" L5's, JL 1000/1, and a JL 450/4. I used 0 gauge wiring to distribution block for the ground then 4 gauge to the amp and a fuse block holder for the power that is 0 gauge in 4 gauge out. either way I have been trying to search on here the laws as to why on bigger applications bigger wire is needed. he is old school and thinks that if he can run small wire in a home why not in a car. lol and he is just a mechanic not the installer at all. I am introducing him into this lovely world. so please help me out. thanks again.
P.S. please don't answer if you don't know what your talking about or if you have nothing valuable to say. All I am trying to do is explain this as easily as possible
tommy... 
Gold - Posts: 1,901
Gold spacespace
Joined: December 10, 2004
Location: United States
Posted: March 09, 2010 at 12:07 PM / IP Logged  

Here is a GREAT site for him to read through...Basic/Intermediate stuff... !

http://bcae1.com/

http://bcae1.com/wire.htm

http://bcae1.com/installationprimer.htm

Virtually all amplifiers have battery, ground and remote connections which must be connected for the amp to operate. The battery connection is the high current +B source that's connected to the battery via a properly fused wire. The size of the power wire is determined by the current the amplifier draws and the length of the wire (from the battery to the amplifier). The ground is another high current connection and is connected to the chassis (body/floor pan) of the vehicle. The ground wire is typically as large as the power wire. The remote connection is a  face low current control input that tells the power supply of the amplifier to power up.

Wire Gauge Current Flow Max Total Amp Power
Class AB (60% eff)
Max Total Amp Power
Class D (75% eff)
0 awg 330 amps 2731 watts 3414 watts
1 awg 262 amps 2168 watts 2710 watts
2 awg 208 amps 1720 watts 2151 watts
3 awg 165 amps 1365 watts 1707 watts
4 awg 131 amps 1084 watts 1355 watts
5 awg 104 amps 860 watts 1075 watts
6 awg 82 amps 683 watts 853 watts
7 awg 65 amps 542 watts 677 watts
8 awg 52 amps 430 watts 537 watts
9 awg 41 amps 341 watts 427 watts
10 awg 33 amps 271 watts 339 watts
11 awg 26 amps 215 watts 269 watts
12 awg 21 amps 171 watts 213 watts
13 awg 16 amps 135 watts 169 watts
14 awg 13 amps 107 watts 134 watts

Wire Gauge Recommended
Maximum Fuse Size
00 awg 400 amps
0 awg 325 amps
1 awg 250 amps
2 awg 200 amps
4 awg 125 amps
6 awg 80 amps
8 awg 50 amps
10 awg 30 amps
12 awg 20 amps
14 awg 15 amps
16 awg 7.5 amps
These are the recommended maximum fuse ratings for the corresponding wire size. Using a smaller fuse than what's recommended here will be perfectly safe.

M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
smtgolf 
Member - Posts: 44
Member spacespace
Joined: February 04, 2010
Location: Indiana, United States
Posted: March 09, 2010 at 12:07 PM / IP Logged  
If he's a mechanic, you could use this analogy:
Look at the electrical system in the car. What size wiring do they use to hook the entire car system up to the battery with? The reason they have 0 gauge equivalent (or multiple 4 ga, etc.) is that they need the capacity for the requirements of the cars electrical system. All the lights, radio, computers, gizmos, etc. They use a bunch of juice and you need wire which will not heat up, melt or fry itself due to the amount of power required being higher than what the wire is capable of carrying. Same principle applies to car stereo/home wiring. The more juice the wire will carry, the more copper (or capacity) it must have to avoid shorting or melting down.
You make sure you have enough capacity to meet any electrical requirement, even if it's just a momentary peak. Especially with music, those momentary peaks can mean a high amount of power required.
You don't want the car catching on fire because a system required 100 amps of juice and the wire melted because it couldn't carry close to that without failure.
Don't know if that might helps but he might understand the idea.
j.reed 
Copper - Posts: 716
Copper spacespace
Joined: January 05, 2009
Location: Arkansas, United States
Posted: March 09, 2010 at 12:18 PM / IP Logged  
smtgolf wrote:
If he's a mechanic, you could use this analogy:
Look at the electrical system in the car. What size wiring do they use to hook the entire car system up to the battery with? The reason they have 0 gauge equivalent (or multiple 4 ga, etc.) is that they need the capacity for the requirements of the cars electrical system. All the lights, radio, computers, gizmos, etc. They use a bunch of juice and you need wire which will not heat up, melt or fry itself due to the amount of power required being higher than what the wire is capable of carrying. Same principle applies to car stereo/home wiring. The more juice the wire will carry, the more copper (or capacity) it must have to avoid shorting or melting down.
You make sure you have enough capacity to meet any electrical requirement, even if it's just a momentary peak. Especially with music, those momentary peaks can mean a high amount of power required.
You don't want the car catching on fire because a system required 100 amps of juice and the wire melted because it couldn't carry close to that without failure.
Don't know if that might helps but he might understand the idea.
I think if you put in perspective of an exhaust system it would be even more under stood for them. A little old 4 cylinder Honda civic has like a 1 inch exhaust. If you tried to use that same exhaust for a big blown V-8 it would not work! The carts Tommy provided show how much current the wire can actually carry. It's really not rocket science.
amp wiring laws and why to go bigger? -- posted image.
tommy... 
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Gold spacespace
Joined: December 10, 2004
Location: United States
Posted: March 09, 2010 at 12:21 PM / IP Logged  
Read up on "The Big3"...This is the foundation...! Water is commonly used for explaining this... Or"thats like trying to suck a golfball through a garden hose"...Or..."Thats like trying to put 10 lb of manure , in a 5 lb bag"
M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
i am an idiot 
Platinum - Posts: 13,666
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: March 09, 2010 at 12:26 PM / IP Logged  
He uses small power wire in home applications because there is 120 volt supply.  Power = Voltage X Current.  Home equipment may pull 10 amps of current.  The current has to be much higher when there is only 14 volts to supply the amp.
tommy... 
Gold - Posts: 1,901
Gold spacespace
Joined: December 10, 2004
Location: United States
Posted: March 09, 2010 at 12:29 PM / IP Logged  

Where is tesla when you need him...?(kirchoff or ohm or edison or a rocket scientist...amp wiring laws and why to go bigger? -- posted image.)

M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!
raydawg357 
Silver - Posts: 769
Silver spacespace
Joined: June 17, 2003
Location: United States
Posted: March 10, 2010 at 10:09 AM / IP Logged  
If he still doesn't get your point, go buy him a thick milk shake and give him a mix drink stirring straw to drink it with.  Different analogy, same principal.
Do it right the first time
DYohn 
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Moderator spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: April 22, 2003
Location: Arizona, United States
Posted: March 10, 2010 at 1:06 PM / IP Logged  
oldspark 
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Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: March 10, 2010 at 6:52 PM / IP Logged  
Ray's milkshake got it.
I use the common water-electricity analogy.
Thin pipe for lots of water... friction, heat, and undersupply.
Same as restrictive oil lines, blocked filters etc.
Pressure (drop) is the voltage (drop); flow rate is the current.
If that doesn't work, the thinner the pipe/cable, the higher its resistance.
The bigger the demand/load, the more waterFlow/current is needed.
V = IR.
Also, P=VI so the same power in a home (120V) requires 10x the current in a car (12V), hence 10x the cable size. (Or here where it is (say) 240VAC, 20x the wire size.)
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