What Happens When an Electrical Circuit Overloads?

Electrical Circuits are designed to handle a limited amount of electricity. An overload occurs when you draw more electricity than a circuit can safely handle. Circuits are made up of wiring, breaker (or fuse, in old wiring systems), and devices (such as light fixtures, appliances, and anything plugged into an outlet). The electricity usage of each device (when running) adds to the total load on the circuit. Exceeding the rated load for the circuit wiring causes the circuit breaker to trip, shutting off the power to the entire circuit.

Circuit Overload

If there were no breaker in the circuit, an overload would cause the circuit wiring to overheat, which could melt the wire insulation and lead to a fire. Different circuits have different load ratings so that some circuits can provide more electricity than others. Home electrical systems are designed around typical household usage, but there’s nothing to prevent us from plugging in too many devices on the same circuit.

In order to prevent circuit overload, you have to know the basics. Know which appliance requires a dedicated circuit installed. A “dedicated circuit” is a circuit that serves only one home appliance. This help protect your appliances, your home, and your family.

• Refrigerator
• Freezer
• Electric range
• Microwave
• Water heater
• Washer
• Dryer
• Dishwasher/garbage disposal
• Furnace
• Heat pump
• Air conditioner (central and window)
• Sump pump
• Hot tub/Sauna/Jacuzzi

Rule of Thumb: If the appliance is fixed and has its own motor or if its critical to your comfort or safety, it probably needs its own dedicated circuit.

Having multiple major appliances on a single circuit will usually overload the circuit and “trip” the circuit breaker, halting the flow of electricity.

After tripping too many times, the breaker wears down and won’t trip. If the breaker does not trip, the electrical overload will overheat the wiring insulation—possibly leading to an electrical fire.

Signs of Overloaded Circuits

The most obvious sign of an electrical circuit overload is a breaker tripping and shutting off all the power. Other signs can be less noticeable:

• Dimming lights, especially if lights dim when you turn on appliances or more lights.
• Buzzing outlets or switches.
• Outlet or switch covers that are warm to the touch.
• Burning odors from outlets or switches.
• Scorched plugs or outlets.
• Power tools, appliances, or electronics that seem to lack sufficient power.