grounds and the big 3

I got a few questions about this topic. First ill start with grounds, i read that posting about measuring it and the ohms should be less than 1, but i just wanted to know when your using your Digital multi meter set to 200 ohms where do you put the positive needle and where do you put the negative needle. Also heard people say ground wires should be short and others say doesnt matter can someone elaborate and usually most manuals for amps say that short is better too, WHOS right and why .  Secondly about the big 3, i read that you put a bigger gauge like 4 or 2 from your battery negative to you chasis thats ok but when your adding a cable from the positive of your battery to your alternator some say putting a 100 amp fuse the flat (WAFER) kind is better and others say  no fuse is necessary i want to know which is right and why. Also is doing all that make an improvement with an average battery and factory alternator or should you just do it with better ones (im asking this hypothetically with a good audio system for say 2 amps  1 1000rms other 4 by 75 rms).   Thanks for your time.  the duce

well..the reason for upgrading the ground wires is you've got a large 4 guage wire comming off your battery going to your audio system and a 10 ga ground wire comming off your battery. right there you're over doing the small 10 ga ground wire, the larger ground wire off the battery will help the flow of power but it will also allow it to take alot more current  where as a 10 ga wire would melt.  the larger wire from the alternator to the battery is the same basic idea. your takeing alot more out of your vehicles stock charging system so to help it perform better you upgrade the wire size allowing better flow of power.  and i'm not sure about a long ground versus a short ground, but i've always run a short ground because it's going to the chassis anyway. find a good common point for all your amps to be grounded to that's fairly close and run your amps there. i mean, why run 10 feet of wire when you only need 2?Tri County KustomZ

certified installer

how do you measure a good ground? I heard you use a DMM,  but i dont know where to put the needles and your suppose to get a ohm reading of less than one for a good ground spot. the duce

thanks man and before you measure you disconnect the postive battery terminal correct?the duce

no need to disconnect the + terminal.

really, it says that in the instructions in this forum but doesnt mention which one and i was guessing the positive because they tell you to measure this in a dead circuit ?the duce

ALright so .5 or less is a good ground? And just say if you want to do it the other way you disconnect the positive battery terminal correct? Just for knowing pupposes.the duce