3 Phase Circuit Breaker Rating Chart

Note that some types of single phase loads are routinely supplied by a 3 phase panel.

3 phase circuit breaker rating chart.

For 3 phase loads you divide the va by the nominal voltage and by the square root of three approximately 1 732. In applications with general load characteristics. A 3 poles circuit breaker can be used on 1 phase system only and only if indicated by the markings or instructed by user manual. Circuit breakers are designed to carry 100 of their rated current while the nec dictates an 80 application.

50 000va 480v 1 732 60 2a. This applies to not more than 3 phase conductors in 1 conduit. A single phase circuit breaker can t be used for three phase supply voltage levels. Conduit sizes may need to be increased if equipment grounding conductors or neutrals are also installed in the conduit.

The wire size chart below shows allowable ampacities of insulated conductors rated up to and including 2000 volts 60 c through 90 c 140 f through 194 f not more than three current carrying conductors in raceway cable or earth directly buried based on ambient air temperature of 30 c 86 f. 75 c rating 30 c ambient wire size awg no. Nec 220 2 use nec 310 16 for ampacity. The next size up is 70a.

Miniature circuit breakers ratings 1 to 63a breaking capacity 15ka 13 c60hb type b 3 5in applications protection and control of circuits against overloads and short circuits. Use the correct size breaker. A 3 poles circuit breaker can be used on 3 phase system using either 2 or 3 poles. Magnetic setting between 3 and 5 in.

Wire size chart and maximum amp ratings. 1 25a 25mm 2. Maximum loading for any branch circuit is 80 of rating of circuit for ampacity of wire for any load. If your total 3 phase load in a 480v system is 50 000va what size breaker do you need.

Full load current and circuit protection data for three phase ac motors. If equipment terminations are rated for 60 c conductors only the 60 c ampacities. Dual element time delay ul class rk5 fuse used with properly sized o l relay circuit breaker instantaneous trip circuit breaker continuous amp rating single phase units 115v 8 4 14 15a 15a 208v 230v 4 4 4 2 14 8a 7a 7a 115v 11 12 15a 15a 208v 230v 5 5 5 4 14 12a 10a 15a. Tripping characteristics bs en 60898 type b.

This rule states that an ocpd can be loaded to only 80 of its rating for continuous loads. Conduit sizes are for three conductors per circuit for three phase motors and two conductors per circuit for single phase and dc motors.