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Can a 3-pole circuit breaker be used in a single-phase application?

Product Line:
MCCB

Resolution:
  • 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.
For reference:
  • 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."
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