When I turn on my air conditioner, the lights go dim. What is going on?

This is usually caused by the air conditioner and the large amount of electricity that is needed to start such a large appliance. When the unit turns on, the current draw is so great in your panel, that there is not enough for all of the other devices that are running at the same time. Most of the time the dimming is so quick that it usually is not that noticeable. Other times lights will dim slowly and not return to full power for few seconds. When this happens, it is time to have the electrical system inspected as soon as possible by a qualified electrician. A hot summer day is not the time to find out that you’re electrical system cannot handle the load. That wouldn’t be cool.