use old wiring

[fearturtle03 10+ year member]

I currently have 2 amps. One running like 300wRMS, the other around 200wRMS. They both use 8awg monster cable for power runs of about 8-10 feet.

I just got a new amp to replace the 300wRMS, and it will be capable of up to 850wRMS, however the sub only uses about 600wRMS. My question is what wire should i use? I have checked like 5 different sites and they tell mem different things. Crutchfield.com has a table that says 8awg would be fine, while others say 6awg and maybe 4awg.

I have 4awg wire right now in my house and may just run it to be safe, but if I did that what size fuse would you suggest. Since 4awg is overkill for 800wRMS, could i get away with fusing it at about 70amp, at the battery? I think the amp has 2x30amp fuses. Or could I get away with not fusing it at all if I am going such a high rated 4awg wire, for not tons of power?

Thanks

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