My daughter in law called because she had tried to replace an ugly ceiling fan and light fixture with a light only fixture and whenever she threw the wall switch it tripped the breaker. I thought it would be easy to figure out but not so.
The old fixture (which she had already removed) was controlled by two light switches and a variable speed fan control. The light switches are at each end of the room - so a three way circuit is in place and the fan control is boxed in a two gang with one of the toggle light switches.
The ceiling fixture has a black, red, white and ground. The red is always hot regardless of how the switches or fan control are set. I even removed the fan rheostat completely and capped off the wires in the wall. Red was still hot regardless of the toggle switch positions. The black wire is hot when the wall switches are on. The white is never hot. When I wire a simple light load across the black and white wires, turn on the wall switch, the black is no longer hot and the light doesn't work.
I can't understand how this could ever have worked. There seems to be no connection between the fan control on the wall and the ceiling fixture. Why does hooking up the light between black and white kill the power entirely. Nothing seems to switch off the red!! Arrggh. Any ideas anyone? Any other tests I can run on the setup which may throw light on what is happening?