Troubleshooting Problems of Lights Dimming When a Heating Appliance Is Switched On

Change the location of a space heater. Move the space heater to another area of the house and plug it in. Determine if the lights are still dimming when it clicks on. If they do not, that is an indication that you were overloading the circuit in that location of the home. If the lights do dim, this an indication that the entire electrical system may be overloading and will need to be upgraded.

See if other high wattage appliances are running simulataneously. If the lights only dim when another appliance is running in conjunction with the furnace or the space heater, this is not as serious. For example, if the lights only dim when you are running the dishwasher or the dryer too, it is just a temporary overloading situation. You can either upgrade your home's electrical system or avoid running high wattage appliances at the same time.

Investigate potential wiring issues. If you smell something burning when the lights dim, or if they flicker on and off in addition to dimming, this is a very serious indication of a problem. In this case, the wiring may have a short and you may end up with a fire in your electrical system. Call an electrician immediately.