Circuit Breaker Voltage Ratings Explained — 120V, 240V, 480V, 600V
Every circuit breaker has a voltage rating that indicates the maximum voltage it is designed to interrupt safely. Installing a breaker with an insufficient voltage rating is a serious safety hazard. Here is a complete explanation of the common voltage ratings and what they mean.
120V and 120/240V
Most residential 1-pole breakers are rated for 120/240V. This means they can be used on 120V circuits (standard outlets and lighting) or on 240V circuits (when used as part of a 2-pole breaker). The dual rating reflects the fact that in a split-phase residential system, each hot leg is 120V to neutral but 240V between the two legs.
240V
240V is the standard voltage for residential 2-pole circuits: electric dryers, ranges, water heaters, and air conditioners. A 2-pole breaker rated for 240V controls both legs of the 240V circuit.
277V
277V is the phase-to-neutral voltage in a 480V/277V wye system, which is the most common commercial building electrical system in the US. Fluorescent and LED lighting in commercial buildings typically runs on 277V. Breakers for 277V lighting circuits must be rated for at least 277V.
480V
480V is the standard 3-phase voltage for commercial and industrial equipment: motors, HVAC systems, manufacturing equipment, and distribution panels. 480V breakers are used in motor control centers (MCCs), switchgear, and industrial distribution panels.
600V
600V is the maximum voltage for low-voltage circuit breakers under the NEC (NFPA 70). It is used in Canadian electrical systems (600V is the standard distribution voltage in Canada) and in some US industrial applications. Square D PowerPact H, J, and L frame breakers are commonly rated for 600V.
Voltage Rating Must Meet or Exceed System Voltage
A breaker's voltage rating must always meet or exceed the system voltage. A 240V-rated breaker cannot be used on a 480V system — even if the current rating is correct. The insulation and contact spacing in a 240V breaker are not designed to safely interrupt 480V faults.
Related Circuit Breaker Resources
- 1-Pole vs 2-Pole vs 3-Pole Circuit Breakers Explained
- What Is Interrupt Rating (kA) on a Circuit Breaker?
- How to Find the Right Replacement Circuit Breaker
Need a 480V or 600V breaker? The AllBreakerSales.com catalog includes industrial breakers in all voltage ratings. Request a written quote to confirm the required catalog number and current availability. Call (951) 903-9804.