Electrical Code Calc. Level II, 2020 NEC

Calculate the resistance of a 6 AWG uncoated copper conductor 500 feet in length.

• 0.246 Ω

• 0.255 Ω

• 0.804 Ω

• 0.836 Ω

Answer explanation

Chapter 9, Table 8

What size copper wire is needed for a 240-volt, single-phase branch circuit supplying a 50-ampere load at a distance of 175 feet? Hold the voltage drop within the recommended Code limit.

• 8 AWG

• 6 AWG

• 4 AWG

• 2 AWG

Answer explanation

Chapter 9, Table 8, 210.19(A)(1), Informational Note No.3

What is the voltage drop on a single-phase, 240-volt circuit carrying 80 amperes on a 3 AWG copper conductor at a distance of 250 feet? (Use k = 13.2.)

• 5 V

• 10 V

• 12 V

• 18 V

Answer explanation

What is the voltage drop on a 3-phase, 480-volt circuit carrying 50 amperes on an 8 AWG copper conductor at a distance of 200 feet? (Use k = 13.2.)

• 7.8 V

• 8.1 V

• 13.8 V

• 16 V

Answer explanation

The lighting load for a two-story, single-family dwelling unit that has outside dimensions of 32 feet by 85 feet is   ?  .

• 5,440 VA

• 8,160 VA

• 16,320 VA

• 28,800 VA

Answer explanation

A unit load of 3 VA per ft² is applied for dwelling units.
32 × 85 = 2,720 ft²
2,720 × 3 × (2 floors) = 16,320 VA
lighting load = 16,320 VA

What is the maximum number of general purpose receptacle outlets permitted on a 15-ampere 120-volt dwelling unit branch circuit?

• 10

• 11

• 12

• Not limited by code

Compute the minimum ampacity for conductors of a branch circuit that supply a noncontinuous load of 13 amperes and a continuous load of 11 amperes.

• 24 A

• 26.75 A

• 27.25 A

• 30 A

Answer explanation

210.19(A)

conductor ampacity = noncontinuous load × 100% and continuous load × 125%
13 A × 100% = 13 A
11 A × 125% = 13.75 A
minimum conductor ampacity = 26.75 A

A fixed, nonmotor appliance in a dwelling unit has a nameplate maximum rating of 40 amperes. The maximum permitted rating of the OCPD required to supply this noncontinuous appliance is   ?  .

• 40 A

• 45 A

• 50 A

• 60 A

Answer explanation

422.11(E)

What is the minimum standard size fuse rating in amperes that can be used to protect a branch circuit supplying a 32 kW, 3-phase, 480-volt, in-duct type electric heater? According to 424.4(B), fixed electric heaters are considered as a continuous load for branch circuits sizing.

• 35 A fuses

• 40 A fuses

• 50 A fuses

• 60 A fuses

Answer explanation

320,000 ÷ (480 × 1.73) = 38.543 A
Continuous load = 38.54 A × 1.25 = 48.17 A
240.6(A) standard size fuses = 50 A

What is the service neutral conductor load (VA) for the electric ranges installed in a six-unit, multifamily dwelling when the ranges are rated 9 kW, 9 kW, 10 kW, 11 kW, 12 kW, and 12 kW?

• 12,400 VA

• 14,700 VA

• 15,400 VA

• 16,100 VA

Answer explanation

220.61(B) & 220.55

6 ranges = 21 kW or 21,000 watts
Neutral = 21,000 × 70% = 14,700 VA