I could use some clarification on art 204.21(B) Feeder Taps and 430.28 Feeder Taps.
I have an outside 480 volt (HRG) switch rack in a Class1, Div 2 location fed from an 800 breaker to a trough with bus bars.
We are adding a size 2 explosionproof starter for a 20HP motor (27amps) above the trough in conduit less than 10 ft away and a 30Amp explosionproof breaker for a 25 KVA transformer more than 25 ft away.
My questions are what size wire is required for the taps?
The size 2 starter, art. 430.28 (1) states they be protected by an overcurrent device on the line side, the rating or setting of which shall not exceed 1000 % of the taps conductors ampacity. In other words 1/10 Th of 800 amps = 80 amps and a # 4 awg (Table 310.16, 75deg) should be used.
The 30 amp breaker should comply with art 240.21(B) Feeder Taps.
Art 240.21(B) (5) Outside Taps of unlimited length does not specify a minimum size conductor for the tap and therefore we could use #10 awg.
If I can use # 10 awg for breaker, why would be different for the starter?
I have an outside 480 volt (HRG) switch rack in a Class1, Div 2 location fed from an 800 breaker to a trough with bus bars.
We are adding a size 2 explosionproof starter for a 20HP motor (27amps) above the trough in conduit less than 10 ft away and a 30Amp explosionproof breaker for a 25 KVA transformer more than 25 ft away.
My questions are what size wire is required for the taps?
The size 2 starter, art. 430.28 (1) states they be protected by an overcurrent device on the line side, the rating or setting of which shall not exceed 1000 % of the taps conductors ampacity. In other words 1/10 Th of 800 amps = 80 amps and a # 4 awg (Table 310.16, 75deg) should be used.
The 30 amp breaker should comply with art 240.21(B) Feeder Taps.
Art 240.21(B) (5) Outside Taps of unlimited length does not specify a minimum size conductor for the tap and therefore we could use #10 awg.
If I can use # 10 awg for breaker, why would be different for the starter?