p = resistivity
L = length
R = resistance
A = cross sectional area
A = p * (L/R)
What I don't understand is how it's physically possible to determine the appropriate gauge wire without knowing the volts OR amperage.
I learned this formula in a book for apprentices of electrical work and in the book this formula was used in a couple examples to solve for cross sectional area and from that determine which gauge wire is appropriate. This may be an odd question which I'm sure you guys get plenty of sense you're working in a field of magic but to clarify my conundrum: right now the only way I can make sense of this formula is to assume that the volts you are working with is an assumed variable.
Also I'm an apprentice for electrical work so I think a big source of my confusion comes from the fact that the which gauge wire I run in a home depends on amperage and amperage solely. What am I not getting?