I have 20 Amp power run to part of my house. The conduit that carries it runs down one of the walls of my garage. I've cut the conduit, inserted a metal junction box, and intend on putting in a single 20 amp outlet in my garage for power tools, etc.
The conduit carried four wires: blue, yellow, gray, gray. As it turns out, I'd thought about this as I turned off two breaker switches, but yes, the conduit is actually carrying two 20 amp circuits. I cut the wires too quick without thinking about it though, and now find myself wondering if it matters which power is matched with which neutral.
I tested by installing the outlet with yellow, and one of the grays, and turned the breakers on (and off) one at a time. I thought that if a lamp plugged in to the outlet turned on, I would have my match. Problem is, I know which breaker is for yellow and blue respectively now, but the lamp works with either neutral.
Given that this is two distinct circuits, AND one of the circuits powers a room with expensive electronics, I'm paranoid.
So, does it matter which neutral is connected in pair with which power? If so, how do I test and figure out which neutral is which?