Voltage Drop Calculations (NEC Code Questions)

Question 1: What is the minimum NEC recommended voltage for a 230 volt load connected to 240 v source?

• 230 V
• 228 V
• 232 V
• 225 V

Question 2: If a 115 volt load is connected to 120 V source. What is minimum voltage that is supplied to the load as recommended by NEC?

• 114 V.
• 115 V
• 120 V
• 117 V

Question 3: What is the voltage drop of two 10 AWH THHN conductors that supply 16 A, 115 V load located 50 ft from the source?

• 1.92 V
• 0,96
• 2.4 V
• 1.8 V

Question 4: Two 12 AWG THHN conductors are placed to connect 8A, 120 V load to the source which is 100 ft distance. What is maximum voltage drop in conductor?

• 3.2 Volts
• 6.4 Volts
• 1.92 Volts
• 2.4 Volts

Question 5: A 3 phase 18 KVA, 208 volts load is connected to panel board with 100 ft length of 2AWG THHN copper conductor. What is the approximate voltage drop in the conductor?

• 1.68 volts
• 3.2 Volts
• 2.4 volts
• 3.8 volts

NEC Reference: NEC 12.9

Question 6: A 12 KVA , 3 phase 480 Volts load should be connected to panel board with a distance of 220 ft. What size conductor is required to prevent the voltage drop from exceeding 3 %?

• 12 AWG
• 10 AWG
• 8 AWG
• 14 AWG

NEC Reference: NEC 12.9

Question 7: A 4 AWG THHN is used to connect a 480 V 3 phase 35 kVA transformer to panel board. what is the maximum length of conductor that can be used in which the voltage drop doesn't cross 3% ?

• 640 ft
• 320 ft
• 720 ft
• 540 ft

NEC Reference: NEC 14.4

Question 8: What is the maximum voltage drop that is recommended by NEC for both branch and feeder conductors?

• 3 %
• 4 %
• 5 %
• 6 %

Question 9: What is 3 phase load that can be connected to a 220 ft, 8 THHN, 480 V conductor with out exceeding the NEC recommended voltage drop?

• 40 KVA
• 42 KVA
• 48 KVA
• 53 KVA

NEC Reference: NEC 12.9

Question 10: What is maximum voltage drop in percentage recommended by NEC for branch circuit conductors?

• 3 %
• 5 %
• 2 %
• 4 %