The answers to this post probably should be added to an FAQ section for Stereos. What I would like to know from the experts on this board is this:

1. What are the speaker wire size cut off points by wattage?

Meaning how many watts is 18ga. good for, how many watts is 16ga. good for, etc...

2. What are the power wire cut off points for an amp by watts?

Meaning how many watts is 10ga. good for. How many watts is 8ga. good for, etc.....

I realize that the length of the run will make a difference so to make it easier, assume 16" runs for the amps (since that seems to be the average length for kits)

There is a formula to covert watts to amps but I can't remeber what it is. You should choose by amount of amps used. here is a chart that tells you wire size with the length of wire considered http://www.partsexpress.com/resources/cablecalc.html

I was thinking Watts of output doesn't necessarily means amps of power usage for an amplifier. I probably worded the question incorrectly. Thanks for the chart!!! I'll see if my instruction show and amperage usage.

My amp puts out 850 watts and I was wondering if I should use 8 gauge or 4 gauge wire. I'm probably going to use the 4 gauge. I'd use 6 gauge if it was easy to find in a high quality wire. Everything I'm finding is either the 8 or 4...

Here is a website that has a lot of conversions for you, just not the one I needed......

http://www.onlineconversion.com/

LOL they are good for nothing... i won't use ANYthing less them 4ga for anythign... i myself am running 1ga in my car.

The formula is PIV and VIR. WHere P = Power (Wattage) I = Current (Amps) R = Resistance (Ohms) and V = Voltage (Volts).

So if you have 2 you can always find the third. Voltage / Current = Resistance of the circiut, Current * Resistance = Voltage, voltage / Resistance = Current. Aaaaand Current * voltage = Wattage, wattage / Current = Voltage and Wattage / voltage = Current.


Dunno if that heps but at least you can convert now. hehe

It's been 27 years since I had my basic electricity and electronics class in the Navy. I've forgotten a few things since then.....



Actually what I did was look at my instructions for my amp. While it didn't tell me what my power consumption would be, they did say I needed a 50 amp fuse in the line. So I looked at the chart in the link (Which I pasted in Microsoft word and saved to my computer) and determined that I require 4 gauge due to the length of the run. Better a little too much than a fraction too little. Thanks a lot for all the help!!!!!



I've already got 14 gauge to my front and rear speakers. They will be handling 50W RMS. I'm going to run 12 gauge to my Sub since it will have 200W RMS going to it.

:rockon:

as an installer of many years,here's what speaker manufacturers have told me: a tweeter should never ever have a larger guage wire,they want a smaller guage because it will add resistance thus affording a little extra protection. subs do need a larger guage and the longer the wire run the larger guage needed because distance=resistance. as for power 10 ga is good for 35-40 amps,8ga is good for about 60 amps,4ga up to 125 amps. one thing that always seems to be overlooked is the ground. if you're running 1000 watts,that factory 10-12ga body ground ain't gonna get it.always use the same ga body & amp ground as the power wire.it also doesn't hurt to run a 4ga strap from the alt to the battery(leaving the factory lead on,also).you would be suprised at how much that alt lead and body ground help out. :rockon:

Just to add to this. Power=(I^2) x R and Power=(V^2)/R. This will help you convert if you don't always know V & I. Just thought I would throw this in.

I have a 4 gauge power wire from my one wire alternator going to the battery. I also added a 4 gauge ground wire directly from the battery to the body in addition to the ground wire to the engine and the ground strap from the head to the firewall. The one wire alternator was the best thing I ever did to that car. No more weird gauge readings or replacing battery and alternator every two years.......

My speakers are full range and not components so the 14 gauge wire should be ok. I figure I need to run 12 gauge to the Sub in any mounting point. I'm not sure where the amp is going yet so I am not sure of the length of the wires..... 8 gauge would work for the power wire if I mounted it under the drivers seat. If I have to mount it in the trunk area, it will be borderline 4-6 due to the length. If it's borderline, I would rather have the larger gauge. I also planned on running the ground wire all the way back to the battery instead of going to the body. What's your opinion of that idea?????

if you have a 4ga body ground,then you're ok.think of the body as a BIG ga ground but be sure to sand off paint so that amp is grounded to nice shiny bare metal,you can repaint over ground once you've done that terminal and all.the less resistance,the less chance of eng noise or other problems

I even use silver solder to solder any connections with splices or crimped ends just to ensure they are good!!!! In fact, I would rather solder two wires together and seal them with shrink tubing than use a crimp connector.