Master Electrician Questions With Complete Solutions

According to the National Electrical Code, the minimum size TW copper conductor for a 5 HP, 3 phase, 230 volt, squirrel cage motor started at full voltage shall not be less than # ___ AWG. correct answer: 14 How many AWG #12 THHN conductors are allowed in a 1" RMC nipple? correct answer: 35 wires How many AWG #12 THHN conductors are allowed in a 1" RMC? correct answer: 26 #12 THHN conductors The circular mil area of a #18 AWG would be ___ CMILS for solid or stranded. correct answer: 1620 According to Table 8 of the NEC and assuming solid uncoated copper conductor; cross-sectional area of 10,380 CM; resistance of 12.6 Ω/circular mill-foot (KF), calculate the conductors resistance at 75 degrees C. ("R" is resistance in Ohms, "L" is the length of the conductor. Use the formula: R=KL/CM.) correct answer: 1.2 Ohm/1000 ft. Using the information in the National Electrical Code, table 8, calculate the total resistance of 495' of uncoated, 18 AWG, stranded, copper. correct answer: 3.85 to 3.93 ohms A compressor motor is rated 1HP, 115V, 16 amps. It is connected to a receptacle providing 120 volts with a 100' extension cord. Due to the load conditions, the maximum voltage drop allowed during starting lockedrotor condition is 30% of motor voltage rating. Using 96 amps for locked-rotor current. Resistance equals impendence. Use resistance values in Table 8 & 9. What is the minimum size of uncoated copper? correct answer: 10 AWG The cross-sectional area of a conductor is decreased by a factor of 4. What is the new conductor's resistance? correct answer: 4 times resistance