07 December 2022
Three pole breaker use in two pole (single-phase) applicationProduct Line:
Powerpact and MasterpactResolution:
- A 3p breaker can be used on a 3 phase system using either 2 or 3 poles.
- A 3p breaker can be used on a 1 phase system only if indicated by the markings as noted below.
Powerpact M P and R
- Per NEC article 240.85: "A circuit breaker with a straight voltage rating, such as 240V or 480V, shall be permitted to be applied in a circuit in which the nominal voltage between any two conductors does not exceed the circuit breaker’s voltage rating."
- According to UL's White book, "3–pole circuit breakers are suitable for use on 3-phase systems only, unless marked to indicate use on 1-phase systems, such as, “For 1–phase connections, use two outside poles,” or an equivalent statement. A 3-pole breaker used in place of a 2-pole breaker on a 3-phase system, such as a 2-pole breaker used in a branch circuit that is actually two legs of a 3-phase system, is acceptable without the 3-pole breaker being specifically marked."
- Three-pole M, P, and R frame breakers have a marking on the cover that states "single phase any 2 poles."
Powerpact H and J
- Three-pole Powerpact L frame Micrologic breakers with all trip units (U31X, U33X, U43X, U44X, U53X and U54X) are marked for single-phase use, but on 240Vac circuits only. Use any 2 poles.
- Three-pole Powerpact H and J-frame thermal-magnetic breakers are marked for single phase use, including MCP.
- Three-pole Powerpact H and J-frame Micrologic breakers with standard trip units (U31X and U33X) are marked for single-phase use
- Three-pole Powerpact B frame breakers are not marked for single phase use.
EDB EGB EJB
- Three-pole Powerpact QB, QD, QG, QJ breakers are not marked for single phase use.
- Three-pole EDB, EJB, and EJB breakers are not marked for single phase use.
- Some three-pole legacy breakers are marked for single-phase use but most are not. Check the label for marking.