Wire gauge question..

[Bryan]

I have a service orinented business that includes lots of windshield time... While driving I often think of random things. Today something crossed my mind that I'd never contemplated before and I know you guys will have the answer I seek...

Why does a 1000 watt amp require 1/0 gauge power and ground cables to make that power, yet only 12 gauge speaker wire to supply it to a 1000 watt sub?

[Bryan]

Nobody??

[chpthril]

Why does a 1000 watt amp require 1/0 gauge power and ground cables to make that power

This side of the amp is DC. However, that 1K watt spec is the AC output, so ohms law cant be strictly applied. In other words, you cant calculate the 1K AC watts with the 12 volt DC to get the DC amp draw.

Why does a 1000 watt amp require 1/0 gauge power and ground cables to make that power, yet only 12 gauge speaker wire to supply it to a 1000 watt sub

This side of the amp is AC.

[kx250frider617]

The length of the power wire also plays a role in selecting gauge of wire. You don't NEED to run 1/0 gauge if your batteries are only 2 feet way.

[kx250frider617]

http://www.the12volt.com/wiring/recwirsz.asp


heres a good guideline to follow.

[Bryan]

Thanks guys.. I've seen the calculators and know what size wires to use and all that.. I was asking more along the lines of whats causing the need for the separate sizes. Example: if I'm using the 12 awg on the input side of a 1000 watt amp, I've got a fire, yet it's ok to use on the output side to push a 1000 watt sub.. I guess I was wondering what the difference is.. Technical info that I didn't know.. Mike hit it with the DC to AC conversion, didn't realize that's what was happening.. Now I'll go research why DC melts wires and AC doesn't

[chpthril]

the12volt site has some good info, but the wire gauge charts can be misleading so use caution. That site is automotive 12V based, so their amp cable charts may factor in that the ground cable is less than 18". In a typical boat system, the B- is as long as the B+, so the total distance is 2X what it is in a car. Also, their "speaker wire size by length and load" makes no sense. Speaker impedance (load) has no bearing. The wire only knows voltage and current running through it, not the impedance of the speaker. Now, the speaker impedance influences the amp's wattage output, but the amp is a huge variable thats not accounted, and cant be accounted for, in that chart. The "Current draw by power" chart looks to factor the efficiency of class-A/B amps. Kinda outdated with the number of more efficient class-D amps out there. Either that or the chart lists the potential peak amp draw for an amp with said RMS. Just seems to be about 2X to the high side.