There is an incandescent ceiling light on the upper floor on my house (built in 1992). It's not a can light. The attic is above this light fixture. The fixture is controlled by 2 3-way switches, one on each end of the hall. There is no dimmer connected to this circuit. 99% of the time, the fixture works perfectly. However, on some afternoons, always on hot days, the lights in the fixture turn on, although no switch has been turned on. When this happens, they appear slightly dimmer that normal. If either wall switch is turned to the "ON" position, the lights in the fixture turn on to full brightness, and if the switch is turned to "OFF", the lights are slightly dimmed. After a few hours, the lights turn off, and everything works normally. Since this never happens at night, and always during hot afternoons, I keep thinking it has something to do with the heat in the attic. But that doesn't make sense, since I've had other light fixtures that overheat, and when that happens, the light turns off, not on. A professional electrician replaced both of the wall switches, but the strange behavior still occurs on hot afternoons. The electrician, and others in local hardware stores are stumped. Have you ever heard of this happening? Any ideas that you have on what is causing this are greatly appreciated! Thank you.

Hello - I have a situation where I have a fan that I occasionally want to turn when when cooling loads come up - and I want to link it to two thermostats (in two different locations), plus a timer - so that whenever any of the three close, the fan will come on. If you take a look at the attached drawing - it shows the (existing) primary fan (not of consequence to this question), plus the proposed secondary fan on another leg and a single thermostat (there are actually two) and a timer. What I am concerned about is how I am proposing wiring this thing - so that there are basically three switches and a looped circuit. What I'm not sure about is if I can connect hot/hot, neutral/neutral and ground/ground - and what, if anything, would happen if two of the switches closed (say, the timer is already closed, and the thermostat closes) at that same time. Would it short if wired this way? Could power present on the open side (or closed side) of a switch be an issue? Thanks in advance for your input - it's appreciated.