A dedicated electrical circuit is one that serves a single appliance or electrical fixture. It's required by the National Electrical Code for certain critical-use appliances and many fixed appliances. No other appliances, fixtures, lights, or outlets can be served by these dedicated circuits. They are most commonly required for appliances that have motors, to ensure there is sufficient power for the start-up load and to run at peak performance. More importantly, dedicated circuits prevent the inconvenience of circuit overloads.
When more than one appliance is served by a single circuit, there is the potential for these appliances to draw more power than the circuit is designed to handle. The result is a tripped circuit breaker or fuse. This is a fairly common occurrence in kitchens in older homes that were installed at a time when the National Electrical Code did not anticipate such a large number of appliances that would be featured in modern kitchens.
Kitchens lean heavily on appliances with motors (mixers, garbage disposers, can openers) and appliances that heat (toasters, pizza ovens, electric grills). Both these types of appliances are notoriously heavy power users. If, for example, you are using a toaster and pizza oven on the same circuit, it's quite common to overload the circuit and trip the circuit breaker. This is especially common in an older kitchen with only one or two 15-amp circuits that are already powering the refrigerator and microwave oven.
Modern kitchens, though, have been installed with at least four, and maybe as many as six or seven 20-amp circuits, and there is much less chance of overloading any individual circuit—especially since the major appliances will have their very own dedicated circuits that can't be used by other fixtures.
The National Electrical Code requires that any appliance or device dedicated as critical-use be served by its own dedicated circuit to eliminate the chance of another appliance or device tripping the breaker and shutting down that critical fixture. These critical appliances include things like furnaces, water heaters, sump pumps, even refrigerators. If one of these breakers trips and you don't know it, you could end up with a flooded basement, a freezing house, no hot water, or a refrigerator full of rotten food.
Appliances That Require Dedicated Circuits
Here's a list of the typical appliances that require dedicated circuits. In addition to these, your local building authority may specify additional appliances or equipment that need a dedicated circuit. And the National Electrical Code, which is revised every three years, may also periodically add additional appliances to this list:
- Electric range (also cooktop, oven)
- Electric water heater
- Furnace (also heat pump)
- Washer (technically a designated circuit)
- Garbage disposal
- Sump pump
- Air conditioner (room and whole-house)
- Bathroom heater (including vent-fan heater units)
- Laundry room receptacles (outlets)
Checking for Dedicated Circuits
Your home's electrical service panel (breaker box) should have labels indicating all dedicated circuits. If you see that any of the above appliances are doubled-up on a single breaker or that they're combined with other equipment, such as lighting or receptacles, talk to an electrician. This is a safety hazard in addition to a nuisance. Electrical circuits that are not up to Code can also be a hindrance to selling your home.