I attempted to install a programmable thermostat today. I got the old one off and the red wire that was supposed to be RH (mine had a #4) fell off. Before I messed with it it looked like the RC and RH were connected somehow. So I installed the system as if it were a 4 wire system leaving the factory jumpers on (short red wire that connects the RH to the RC on the thermostat board). I ran the heat and it came on, then I ran the air and left it on. Well, I was sitting at my computer and all the power to the house 'blinks' and everything shuts off, but comes back on. I checked the breaker box and everything was still on as well. I'm a little scared at the trouble I've caused...there was one wire left over, a blue one, but it wasn't connected to anything when I started. Do I need to cut the sheath back on the bundle to make sure there isn't another red wire I missed??? This house was built in 1986...and I *think* it is a 24v system..not sure tho...

shunned

Most likely it IS a 24V transformer running your stat so I would not be worried that you may have done something to cause a spike in your electric service. With this heat some electric companies do experience some power fluctuations..