I am working on a house that has a 4" well, there are 3 wires coming out, 1 red, 1 black and 1 yellow, could someone tell me how to wire it to a pressure switch, I am not sure if it is 120 or 240 volts, thanks !!!!
You're serious??? You don't even know if it is 120v or 240v, yet you want someone to tell you how to wire it??
Red, black and yellow is an indication of a remote capacitor start. You need a control box along with the pressure switch.
Might I humbly yet strongly suggest hiring someone to do this for you.
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.