Does anyone know the formula for calculating total AMPS? For example if you add up all your gear's maximum wattage and say you come to 1,000 watts, how many amps is that?

I know you're also supposed to add 10% of buffer to prevent overloading the circuit.

Hi
anyone remember this stuff :) anyway, I know of someone who has a ton of
Ampex 765 (i think its 765-anyway its close) this is 1" data tape on 12"
reels and it all looks in pretty good shape. Anyway the question is can I
use this tape on my 1" machine for recording music. Will I experience
problems with it? will is cause excessive head wear?