The 120 volt circuits require a single pole breaker, using only one phase of the electrical service. These circuits provide power to lighting, outlets and furnaces. The breakers are usually sized at 15 or 20 amps.
In a 240 volt circuit, a two-pole breaker uses both phases of a circuit. Examples of 240 volt appliances would be an electric range, an electric stove or central air conditioning.
These appliances don’t work unless both “A” and “B” phases are working. Most of these examples would require a two-pole 30 amp breaker.
Remember to size your breaker by the name plate rating on the device you are connecting to.
