Re: Big watt home theater speaker wiring
If this is a home stereo system using non commercial (consumer or audiophile) amplifiers the NEC doesn't apply and you are free to use any wiring method you choose regardless of output wattage. What to use? Just as always more power=bigger wire. The amplifier specs should recommend minimum sizes. The on- line audio dealer websites abound with this stuff. Just don't fall for the $$$ oxygen free litz wound garbage. Plain old copper wire is just fine.
Commercial amplifiers, on the other hand, will have the NEC class of wiring required (Class 1, 2 or 3) marked near the output terminals. This is determined by UL and has no rhyme or reason. I have seen 600 watt amps require Class 2 wiring and 400 watt amps require Class 1 wiring. The only way to determine commercial amplifier wiring requirements then is to look at the back panel of the amplifier. Nothing in 725 is applicable.