Controls & Disconnects — Texas Master Practice Questions

6 questions · 4% of the NEC Knowledge exam

Worked questions

1. A healthcare facility is required to install an emergency lighting system. According to the 2026 NEC, what is the minimum required duration of illumination for emergency lighting in this facility?

A1 hour
B90 minutes
2 hours
D3 hours

Exam tip

Remember that healthcare facilities have specific requirements for emergency systems, including lighting, that are more stringent than general occupancy requirements.

Why C is correct

Healthcare facilities are required to have emergency lighting systems with a minimum duration of 2 hours of illumination according to 2026 NEC Article 700.10(A)(1). Option A, B, and D are incorrect as they do not meet the specific requirements for healthcare facilities.

2. In a commercial building, a 100-ampere branch circuit is supplying a piece of equipment that requires a 125-ampere overcurrent protection device. According to the 2026 NEC, what type of overcurrent protection device should be used?

A100-ampere circuit breaker
125-ampere circuit breaker
C100-ampere fuse
D125-ampere fuse

Exam tip

Be aware of the requirements for overcurrent protection in relation to the rating of the equipment and the branch circuit.

Why B is correct

The NEC requires that the overcurrent protection device for a branch circuit be equal to or greater than the rating of the equipment being protected. Therefore, a 125-ampere circuit breaker should be used to protect the 100-ampere branch circuit.

3. In a motor control center, the disconnecting means for each circuit must be accessible from the point of control. According to the 2026 NEC, what type of disconnecting means is typically used for this purpose?

Circuit Breaker
BGround Fault Circuit Interrupter (GFCI)
CIsolating Transformer
DManual Motor Starter

Exam tip

Familiarize yourself with the types of disconnecting means required in various applications as per the NEC.

Why A is correct

Circuit breakers are commonly used as disconnecting means in motor control centers, as they provide the necessary isolation from the source of power and are accessible from the point of control. GFCIs, isolating transformers, and manual motor starters are not typically used as primary disconnecting means for this purpose.

4. In a multi-family dwelling, the NEC requires the installation of arc-fault circuit interrupters (AFCIs) in all branch circuits to protect against electrical fires. What is the primary purpose of an AFCI?

ATo provide overcurrent protection
To detect and interrupt arcing faults
CTo prevent electrical fires
DTo provide grounding protection

Exam tip

Recognize the importance of AFCIs in preventing electrical fires and understand their operation and requirements as per the NEC.

Why B is correct

The primary purpose of an AFCI is to detect and interrupt arcing faults, which are a leading cause of electrical fires. Overcurrent protection, preventing electrical fires, and grounding protection are not the primary functions of an AFCI.

5. In an office building, a series of lighting fixtures are being installed. According to the 2026 NEC, what is the maximum spacing between luminaires that can be connected in series for control purposes?

A3 feet
B5 feet
C7 feet
10 feet

Exam tip

Understand the limitations and requirements for the installation of lighting fixtures and control systems as outlined in the NEC.

Why D is correct

The NEC specifies that the maximum spacing between luminaires connected in series for control purposes is 10 feet. Options A, B, and C are incorrect as they exceed the maximum spacing allowed.

6. When installing a grounding electrode in residential construction, the NEC requires a minimum length of 8 feet for the electrode. What is the primary reason for this requirement?

To increase the surface area for better grounding
BTo ensure the electrode is below the frost line
CTo provide a sufficient length for the bonding wire
DTo minimize the risk of corrosion

Exam tip

Understand the importance of grounding and bonding in residential construction and the specific requirements outlined in the NEC.

Why A is correct

The primary reason for the minimum length requirement of 8 feet for grounding electrodes in residential construction is to increase the surface area, which enhances the grounding effectiveness. The other options are not the primary reasons for this requirement.

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Controls & Disconnects — Texas Master Practice Questions

Worked questions

1. A healthcare facility is required to install an emergency lighting system. According to the 2026 NEC, what is the minimum required duration of illumination for emergency lighting in this facility?

2. In a commercial building, a 100-ampere branch circuit is supplying a piece of equipment that requires a 125-ampere overcurrent protection device. According to the 2026 NEC, what type of overcurrent protection device should be used?

3. In a motor control center, the disconnecting means for each circuit must be accessible from the point of control. According to the 2026 NEC, what type of disconnecting means is typically used for this purpose?

4. In a multi-family dwelling, the NEC requires the installation of arc-fault circuit interrupters (AFCIs) in all branch circuits to protect against electrical fires. What is the primary purpose of an AFCI?

5. In an office building, a series of lighting fixtures are being installed. According to the 2026 NEC, what is the maximum spacing between luminaires that can be connected in series for control purposes?

6. When installing a grounding electrode in residential construction, the NEC requires a minimum length of 8 feet for the electrode. What is the primary reason for this requirement?

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