What Does It Mean When Your Heater Is Making the Electricity Flicker?

Voltage Drop

• When an appliance like an electric heater draws a heavy current, the available voltage level may drop when it turns on. An incandescent light on the same circuit will momentarily dim as the current flow increases to compensate for the voltage decrease. When the heater turns off, the voltage level returns to normal and the current flow to the light decreases. The changing current flow and varying voltage level cause the light to flicker.

Circuit Loading

• Circuits that are already moderately loaded may be partly responsible for the cause of flickering lights when an appliance like a heater is added to them. All wires have resistance, which causes voltage to drop. Each light or appliance adds to the drop; when it becomes significant, the changing voltage level caused by the heater becomes noticeable as a flicker in the lights. Operating fewer loads on the circuit may pinpoint this as the cause of the flickering.

House Wiring

• The wiring in a house may contribute to flickering in conjunction with an electric heater. Poorly made connections cause voltage drops and overheating. If wire splices or terminal connections don't make good contact, the splice or connection causes another voltage drop because the resistance is high. A lighting circuit without the heater won't flicker because the load does not change. When the heater is added, the thermostat that turns the heating element on and off changes the load and makes the lights flicker.

Issues

• A flickering light should always be investigated. Whether the flickering is caused by an electric heater or another appliance, it could indicate a problem with your home's wiring. Poor connections in wire splices or terminals can overheat and cause fires.

  Flickering that occurs on one circuit and not on another, if you move the heater, indicates a potentially serious problem that should be checked by a pro. So do lights that flicker rapidly, or when some dim and others brighten.

  A continuously low voltage may cause problems with other appliances, including motors that burn out and poor or inefficient operation.