Re:Preventative Medicine - get a UPS (Score 1)

It sounds like you may have a bad neutral. In the US, we get two hots and a neutral from the electric company into a building. From each hot to neutral is 120 volts for receptacles and the like; across both hots you get 240 volts for heavy loads like stoves, dryers, and central air units. If the neutral opens up the voltage doesn't divide evenly. It will sag on the more heavily loaded hot leg and soar on the other. You notice this when you switch on heavier loads like a refrigerator or toaster. Open, or half-open neutrals are not rare. The connections outside can corrode due to aging. Old boxes, especially in a cellar or other damp location, are another culprit. We had this happen due to an incompetent electrician. He replaced the circuit panel and forgot to tighten the neutral screw. The kitchen lights got super bright when we turned on the one of the stovetop elements, and dimmed when we turned on a second. Among other things we lost the doorbell transformer, the garage door opener, and a few digital clocks. Settlement was a lot of fun. The real estate agent had brought this guy in to replace the box for a finicky buyer. The damages came out of their commission. They didn't argue much - it was their electrician, and he could've burnt down my house.