I have been experiencing lights flickering momentarily for several years one or two times a day. It became more evident when I hooked my computer and tv to seperate UPC battery backups last fall. Now the UPC will click when the lights flicker. I have had the power company check the incoming line, tighten the incoming wires to my 400 amp distribution box and put on a recording meter which showed what they call a minor (114 to 124) fluxuation in the voltage. I have had an electrician tighten the wiring in each of my two distribution panels. Both the electrician and the power company thinks it may be the 240 heat pump. However the drop in voltage as measured when the heat pump came on was 5 to 6 volts over 5 to 10 seconds. What I am experiencing is a voltage fluxuation of less than a second. The voltage dip or sag also occurs in the evening after the heat pump shuts off or during times of low temps when the furnace is using propane back up.
The outdoor transformer is relatively new and is rated at 50kv? and serves 5 houses. One of my neighbors says they also experience a sag, the others don't notice it. Two of the neighbors have new heat pumps. I also have a small spa heater that goes on and off and a septic pump motor (but I can hear when the septic pump goes on and it does not coincide with the sags).
The house wiring is installed in 1974.
I hope I have given enough information for some one to say " aha I know the answer"! Thanks in advance for any help you can provide. :)