Part of having a safe and efficient home electrical system is protecting certain appliances with their own circuit breaker. This kind of design is known as a dedicated circuit. While the National Electrical Code (NEC) requires certain appliances to be on their own circuit, there are times when it is advisable to place other appliances on their own circuit even though it isn't required.
High Wattage 120-Volt Appliances
Any appliance that uses a large number of watts should be on its own circuit. For a 20-amp circuit at 120 volts, the maximum wattage that circuit can handle is 2400. However, the recommended "safe load" for any standard circuit is a total wattage of 80 percent of the circuit's capacity. For example, the safe load for a 20-amp circuit is 1920 watts (2400 x 0.8 = 1920). It is safe to assume that a 1500-watt load or greater should have a dedicated circuit, also known as an individual branch circuit. A 120-volt baseboard heater is a good example. Many appliances will require a dedicated circuit, so check the manual before using a new piece of equipment.
Any 240-volt appliance will need its own circuit. These types of appliances have special plugs or connections that cannot be used with standard 120-volt outlets. Depending on the energy demands of the appliance, it may need a 30-, 40-, or 50-amp 240-volt circuit. Electric ovens, dryers, water heaters and heat pumps are all 240-volt appliances that need their own dedicated circuit.
Although the NEC does not require a dedicated circuit for the fridge, it is a good idea to dedicate it. Fridges can use a lot of energy and they will operate more efficiently and last longer if they have a dedicated power supply. Even if a fridge only requires a 15-amp circuit, it is a good idea to provide a 20-amp circuit for improved operation.
Exceptions for Gas Appliances
Gas appliances that only require power for a spark or starter, such as a gas oven or clothes dryer, can share a circuit. These appliances will have a 120-volt cord and plug connection. For example, a gas dryer located next to an electric washer can share a circuit. The power demands of the gas appliance are so low that its load is negligible.
Small Appliance Circuits
The NEC requires a minimum of two dedicated small appliance circuits serving the kitchen countertop areas. These circuits provide power to small appliances such as toasters, mixers, blenders and juicers. Additionally, a dedicated circuit must serve any basin or sink, including the bathroom and laundry area. In all of these cases, the circuit must be a ground-fault circuit interrupter (GFCI)-protected circuit.
Additional Dedicated Circuits
In addition to the appliances mentioned, the following appliances need a dedicated circuit: heating units, sump pumps, water pumps, hot tubs and garage door openers. Dedicated circuits for garbage disposers and microwaves often are recommended and may be required by local code. If you have any question of whether an appliance needs its own circuit, consult a certified electrician.
- Electrical Wiring: Residential; Ray C. Mullin
- Wiring a House; Rex Cauldwell
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