installing ceiling fan, when remove light fixture, it has 4 wires system, wires used: white red and green with one light switch, what is black for, it has a wire nut, but has nothing connect to it
Look in the box where the switch is installed. Is there a black wire that also has a wire nut on it? If so, someone used a little forethought when they ran the wires to this switch. You will connect one of the wires (red or black, doesn't matter which) to the black wire of the fan, and the other goes to the blue wire of the light kit on the fan. Then connect the white to white, and the ground wire goes to the mounting bracket or bare copper wire of the fan. At the switch box, you will need to add another switch for the fan. If there is only room for 1 switch, you can buy a combination fan/light switch that fits in the space of 1 switch, but has controls for both the fan and the light. Hope this helps.
people use a four wire system when they are going to operate one fixture in more than one location or continue power to another fixture or outlet. Red and black are always hot. If the black wire was only wire nutted, then don't use it, just leave the wire nut on it. Sometimes people run a four wire because that is what they had lying around. Also, if you want to run the fan independently from the light, you could use a four wire to run power independently from a switch where one side of the switch runs the fan and the other runs the light.
Either way green is ground, white is common, red is live and black is live. It is technically irrelevant which is which but black and red are one each for the fan and optional light. If black has a wire nut on it leave it that way it is for the optional light.
Does the switch turn on from another location? Red should be hot, white neutral and green ground. Buy a cheap tester to be sure. Easy way? reconnect whatever way the light was functioning. Black should be a hot wire, but bear in mind white can be hot in a switch loop. Test it. You need 1 hot, a neutral and a ground.
Before I answer this again I would like to know. What has 4 wires the ceiling box or the fan/light kit. Are they comming out of a three wire together? (one piece of romex) from differant directions? Black is hot. colored(other than green) is wired to hot and may be hot also. White is neutral same as ground but should not be wired to or with a ground Green or bare copper is ground
