amp wiring laws and why to go bigger?

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

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

https://bcae1.com/

https://bcae1.com/wire.htm

https://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.

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

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.

smtgolf wrote:

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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.

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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.

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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"

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

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.

Where is tesla when you need him...?(kirchoff or ohm or edison or a rocket scientist...)

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

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.

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Do it right the first time

https://www.the12volt.com/info/recwirsz.asp

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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.)

raydawg357 wrote:

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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.

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Couldn't agree more.

Thanks a bunch guys for all the info. Its funny you referred to the exhaust issue cause me and him have had that debate as well! He thinks the bigger isn't better... i told him it honestly debates on the point of what the application is. and I tried the garden hose effect but to no avail. So this should help out a lot better.

He's probably oldskool....
For exhausts, bigger isn't better - until you go bigger again....

Based on what a guru once said to me....
The calcs for exhaust performance (extractors etc) involve exponentials etc. They are curves that vary with differing setups (ie, height, peaks, troughs, the number of peaks etc).

Anyhow, this took place in the dark ages when people were not only dumber, but lacked computers (I jest - only the latter is true).
So computations were complex....
They would solve a given system and find that a 2-1/2" exhaust was the lowest impedance (whatever). Increasing to 2-3/4", 3" etc made things worse. Hence the conclusion "bigger isn't always better".

The problem was, they would have found that maybe 6" and 12-1/4" were other solutions....

These days the mathematical technique of differentiation is used
to find where the highs (or lows) are. You then solve that equation to find when it equals zero. (Because differentiating something is to find its rate of change or gradient, and the gradient at max & mins is zero. Same as distance - velocity - acceleration.)

Or we just plug the values in to a computer and see the displayed solutions.....

And of course there is the same old same-old....
Our equations are only models - they are NOT the real thing. (I love it when someone says it can't be done because the model doesn't fit, yet they are staring at the impossibility. I think those infinite and macro lenses fitted that - ie, they broke Lenses Law (1/f = ...) - they are the lenses that show an ant eating up close yet the distant mountain all in focus...)