What is the Difference Between Single-Pole and Double-Pole Circuit Breakers?

26 Jul, 2017
Posted by: Circuit Breaker Wholesale

There are many kinds of circuit breakers in existence, designed for varying purposes in home electrical systems, commercial use, and industry.

The most common breakers utilized in home systems are single-pole and double-pole circuit breakers.

Difference Between Single-Pole Double-Pole Circuit Breaker

Physical Circuit Breaker Differences

Physically, single-pole and double-pole circuit breakers have obvious differences. Single-pole breakers are thinner and have a single switch for on/off positions.

A double-pole breaker will have the appearance of double the width of the single-pole breaker, with the appearance of two switches, bridged to function as a single switch.

Double-pole breakers will also require twice the space in a breaker panel as their single-pole counterparts.

Electrical Differences

Single and double-pole breakers (SP and DP) vary in the number of conductors connected to the breaker, as well as the power and amperage ratings of the breakers.

Single-pole breakers:

Provide 120-volt service
Are rated for 15-20 amps
Connect with two wires – one hot and one neutral

Double-pole breakers

Provide 240-volt service
Handle amperage ratings 20-60 amps
Have three conductors – two hot and one common neutral connection

Application of Single-Pole and Double-Pole Circuit Breakers

Single-pole breakers are most appropriate for non-heating or low amperage household use:

Typical household lighting
Light appliances such as vacuums, hair dryers, light power tools
Outdoor lighting

SP breakers are wired with a single hot wire and neutral wire. In the event the circuit exceeds the breaker’s rating through a short or overload condition, the breaker trips, breaking the power source to that single circuit.

Double-pole breakers are warranted for power sources requiring higher voltage and amperage ratings:

Electric water heaters
Central air conditioners
Electric ranges
Electric clothes dryers

Wiring a DP breaker includes two hot connections, sharing a single neutral wire. In a circuit protected by a DP breaker, if either of the hot connections causes a short or overload, the breaker will disrupt power to both sides.

DP breakers are most often utilized to protect such devices as listed above, but they may also be used to protect two lower-voltage (120 volt) circuits. When the breaker is wired and used in this manner, it’s important to remember that a short in either connection will create a break in power to both sides of the breaker.

SP breakers can also be utilized to protect 240-volt equipment, by utilizing two single-pole breakers, connecting each side of the appliance such as an electric dryer to a single breaker. The critical issue with this type of wiring is that if a short is detected on one circuit, only that breaker will trip. The remaining circuit to the appliance will still be hot, which could create a very dangerous situation.

National and local codes typically restrict this use of dual SP breakers for 240-volt service requirements.

Find the Circuit Breakers You Need

When replacing or adding circuit breakers to your existing service panel, be certain to utilize a breaker that is the same as the original or has been verified to be compatible with the unit being replaced. It is generally inadvisable to install breakers manufactured by someone other than the maker of the panel.