Calculations & Theory — Texas Master Practice Questions

Exam tip

Always check if the total load exceeds 150% of the branch-circuit rating to determine the minimum required rating.

Why C is correct

According to 210.16(A), the minimum branch-circuit rating is the sum of the loads served. Here, 8 fixtures at 20A each equals 160A. However, 210.16(B) states that if the sum of the loads exceeds 150% of the rating of the branch-circuit, the branch-circuit rating shall be increased to the next standard size. 150% of 160A is 240A, which is the next standard size above 160A.

Exam tip

Always refer to 250.66 for the minimum grounding electrode conductor requirements based on the service voltage and type.

Why B is correct

According to 250.66(A), the grounding electrode conductor must be at least 4/0 AWG copper for a 3-phase, 4-wire, 480V service. This ensures proper grounding and bonding for the service.

Exam tip

Remember the specific exemptions for AFCI requirements in different locations as outlined in the NEC.

Why A is correct

According to 210.12(A)(2), circuits that supply kitchen countertop outlets are exempt from the AFCI requirement. This is because AFCIs are not required in kitchen countertop outlets, as specified in 210.12(A)(1).

Exam tip

Conduit wiring is often the preferred method when walls are accessible during installation.

Why D is correct

According to 300.4(A), conduit wiring is the preferred method when walls are open and accessible. It provides protection and organization for the wiring and is suitable for temporary or permanent installations.

Exam tip

Remember that the overcurrent protection for motors must be at least 125% of the full-load current.

Why A is correct

According to 430.52(A)(1), the overcurrent protection for a motor must not be less than 125% of the motor's full-load current. Therefore, 125% of 100A is 125A, which is the minimum required overcurrent protection.

Exam tip

Always check the specific requirements for weatherproof covers based on the location and type of electrical installation.

Why C is correct

According to 406.8(A)(2), a Type 3 weatherproof cover is required for receptacle outlets in outdoor swimming pools and similar locations. This type of cover provides protection against splashing water.