Originally Posted by
MLA
The downside to the above rule-of-thumb from wiki, is that's its assuming that the 8ga is of adequate size for each amp to run from the block to the amp.
Depending on each amp's potential current draw, and the distance from the block to each amp, 8ga may or may not be sufficient. You may need 4ga, so this would change the whole equation.
The wire ga chart I use has 8ga carrying up to 60A for a length of up to 5ft. In most installs, the amp will not be more then 5 ft from the distribution block . More then 60A or further then 5ft, you should step up to 4ga.
In the grand scheme of things, wire is inexpensive, so you would only be talking a few bucks more to step up to 4ga for all 4 amps. $.02