sizing the cable size and the CB for the capacitor sizing the cable size and the CB for the capacitor Alajji (Electrical) (OP) 10 Apr 16 10:16 when we design cable size for the capacitor we multiply the normal current by 1.35 and the CB shall be size to 1.5*normal current? does my statement above true? regards RE: sizing the cable size and the CB for the capacitor 7anoter4 (Electrical) 12 May 16 09:17 Indeed ,NEC Art.460 Capacitors. 460.8 Conductors. (A) Ampacity.: The ampacity of capacitor circuit conductors shall not be less than 135 percent of the rated current of the capacitor. B) Overcurrent Protection. An overcurrent device shall be provided in each ungrounded conductor for each capacitor bank. The rating or setting of the overcurrent device shall be as low as practicable. 240.4 Protection of Conductors. Conductors, other than flexible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G). In my opinion that means in order to protect the conductors CB rating has to be 135% also. 460.9 Rating or Setting of Motor Overload Device. “Where a motor installation includes a capacitor connected on the load side of the motor overload device, the rating or setting of the motor overload device shall be based on the improved power factor of the motor circuit. The effect of the capacitor shall be disregarded in determining the motor circuit conductor rating in accordance with 430.22.” In my opinion, that means in order to protect the conductors CB rating has to be 125% motor rated current.