Question 1

Per NEC Table 314.16(B), what volume allowance must be counted for each 14 AWG conductor when calculating box fill?

Accepted Answer

Table 314.16(B) assigns 2.0 cubic inches of volume per 14 AWG conductor. A 12 AWG conductor counts as 2.25 cu in. Always include conductors, devices (2x the largest conductor), and clamps in the total fill.

Question 2

When a raceway contains more than two current-carrying conductors, what is the maximum conduit fill percentage permitted by NEC Chapter 9, Table 1?

Accepted Answer

NEC Chapter 9, Table 1 limits fill to 40% for three or more conductors, 31% for exactly two, and 53% for a single conductor. The reduced percentages account for heat dissipation and pulling tension.

Question 3

What is the recommended maximum voltage drop for a branch circuit under the NEC informational notes (210.19)?

Accepted Answer

The NEC informational note recommends a maximum 3% voltage drop on a branch circuit and 5% total for feeder plus branch circuit combined. These are recommendations, not enforceable requirements, but they appear frequently on exams.

Question 4

Per NEC Table 250.66, what is the minimum copper grounding electrode conductor for a service with 3/0 AWG copper service-entrance conductors?

Accepted Answer

Table 250.66 requires a 4 AWG copper grounding electrode conductor for service conductors sized 2/0 or 3/0 AWG copper. The grounding electrode conductor is sized from this table based on the largest service-entrance conductor.

Question 5

What is the minimum number of 20-ampere small-appliance branch circuits required for a dwelling-unit kitchen per NEC 210.11(C)(1)?

Accepted Answer

NEC 210.11(C)(1) requires at least two 20-ampere small-appliance branch circuits to serve the kitchen, pantry, dining room, and breakfast-room receptacles in a dwelling unit.

Question 6

When sizing conductors and overcurrent protection for a continuous load, the load must be multiplied by what factor?

Accepted Answer

Per NEC 210.19 and 210.20, conductors and the overcurrent device for a continuous load must be sized at 125% of the continuous load (a load expected to operate for 3 hours or more).

Question 7

Per NEC 430.22, a single continuous-duty motor branch-circuit conductor must have an ampacity of at least what percentage of the motor full-load current?

Accepted Answer

NEC 430.22 requires branch-circuit conductors for a single continuous-duty motor to be sized at 125% of the motor full-load current (FLC) taken from Tables 430.247 through 430.250.

Question 8

Per NEC Table 250.122, what is the minimum size copper equipment grounding conductor for a circuit protected by a 20-ampere overcurrent device?

Accepted Answer

Table 250.122 requires a 12 AWG copper equipment grounding conductor for circuits protected at 20 amperes. The EGC is sized from the rating of the overcurrent device protecting the circuit.

Question 9

Under the NEC 240.4(D) small-conductor rule, what is the maximum overcurrent protection for 12 AWG copper (absent a specific exception)?

Accepted Answer

NEC 240.4(D) caps overcurrent protection at 20 amperes for 12 AWG copper, 15 amperes for 14 AWG copper, and 30 amperes for 10 AWG copper, regardless of the higher ampacities the ampacity tables might otherwise allow.

Question 10

A 2,000 sq ft dwelling is calculated under the 2023 NEC. What is the general lighting load before demand factors are applied?

Accepted Answer

Under the 2023 NEC, the dwelling general lighting load is 3 VA per square foot: 2,000 sq ft x 3 VA = 6,000 VA. Demand factors from 220.42 are then applied (100% of the first 3,000 VA, 35% of the remainder) to size the service or feeder.

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