Planning kitchen circuitry is a critical step when designing a new home, because stoves, refrigerators, microwaves, toasters and coffee makers draw significant amounts of electricity. In older homes built before the introduction of today's advanced appliances, a single circuit was usually adequate to service all of a kitchen's electrical needs. But when several modern cooking devices are used at once, it may cause the circuit breaker to trip. One way to eliminate that risk is to set up a separate circuit for the refrigerator.
Most household refrigerators draw between 500 and 750 watts of power during routine operation. With a 110-volt current, a 750-watt appliance will require 6.8 amps to operate. The formula for converting watts to amps is: Watts divided by Volts = Amps. A refrigerator will use roughly half of the available amperage of a standard 15-amp circuit, and over one third of a 20-amp circuit.
The National Electrical Code specifies that a circuit should only carry 80 percent of its rated load during normal operation. A 15-amp circuit under these circumstances would have an actual load rating of 12 amps. With a 6.8-amp load on the circuit, the recommended working reserve capacity would be only 5.2 amps. Increasing the capacity to 20 amps will give a larger safety margin, but care should still be exercised.
The leftover capacity of a 15 amp circuit would probably support an electric can opener. Attempting to operate a microwave or toaster on this circuit while the refrigerator's compressor is operating would result in a tripped circuit breaker. Any additional appliance on the same 15-amp circuit would need to be sized carefully.
One additional argument in favor of a separate circuit for refrigerators is the risk of an unnoticed power outage. In an overload situation, the breaker will shut off power to the circuit. When this happens, the breaker must be manually reset to restore power. This will not be a significant problem if the power is only off for a few minutes. However, if the outage happens while the homeowner is away for an extended period of time, the food in the refrigerator and freezer may become warm and spoil.