3 Phase Circuit Breaker Rating Chart

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.

3 phase circuit breaker rating chart.

Nec 220 2 use nec 310 16 for ampacity. Use the correct size breaker. Conduit sizes may need to be increased if equipment grounding conductors or neutrals are also installed in the conduit. This rule states that an ocpd can be loaded to only 80 of its rating for continuous loads.

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. In applications with general load characteristics. 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. Warning voltage drop nec 310 16 wire ampacity tables do not take into account voltage drop only thermal limit.

A 3 poles circuit breaker can be used on 3 phase system using either 2 or 3 poles. Wire size chart and maximum amp ratings. If equipment terminations are rated for 60 c conductors only the 60 c ampacities. If your total 3 phase load in a 480v system is 50 000va what size breaker do you need.

Tripping characteristics bs en 60898 type b. Full load current and circuit protection data for three phase ac motors. For 3 phase loads you divide the va by the nominal voltage and by the square root of three approximately 1 732. 1 25a 25mm 2.

A single phase circuit breaker can t be used for three phase supply voltage levels. 50 000va 480v 1 732 60 2a. Maximum loading for any branch circuit is 80 of rating of circuit for ampacity of wire for any load. Note that some types of single phase loads are routinely supplied by a 3 phase panel.

This applies to not more than 3 phase conductors in 1 conduit. Circuit breakers are designed to carry 100 of their rated current while the nec dictates an 80 application. Magnetic setting between 3 and 5 in. 75 c rating 30 c ambient wire size awg no.

The next size up is 70a. Remember that 80 is the inverse of 125 0 80 1 divided by 1 25 and as such the rules are indeed identical in their end requirement.