Free NEC Code Basic Questions and Answers

Question 1

Every box, cabinet, or temperature fitting, such as a conduit body, must have electrical nonmetallic tubing secured within:

Accepted Answer

3 ft

Answer

NEC Article 362.30(A) requires Electrical Nonmetallic Tubing (ENT) to be securely fastened in place at intervals not exceeding 3 feet (900 mm). Furthermore, it must be secured within 12 inches (300 mm) of every box, cabinet, or fitting. These requirements ensure the tubing is properly supported, preventing sagging and protecting it from damage.

Question 2

Motor feeder tap conductors that are not more than ___ length must have an ampacity that is at least ten times the feeder protection device's rating.

Accepted Answer

10 ft

Answer

The 10-foot tap rule, found in NEC 240.21(B)(2) and referenced for motor feeder taps in 430.28, permits tap conductors not exceeding 10 feet in length under specific conditions. This rule allows for short, unprotected taps from a feeder, provided they meet specific ampacity requirements and do not extend beyond the control device they supply. The 10-foot length is a recognized short tap rule in the NEC for providing flexibility in connecting loads.

Question 3

For the purpose of sizing branch circuits, an electric heater with a capacity of __ gallons or less is regarded as a continuous load:

Accepted Answer

120

Answer

According to NEC 422.13, a storage-type water heater with a capacity of 120 gallons (450 liters) or less is considered a continuous load. This classification requires the branch circuit conductors and overcurrent protection to be sized at 125% of the water heater's nameplate rating. This ensures the circuit can safely handle the sustained current draw typical of water heaters, preventing overheating and ensuring long-term reliability.

Question 4

With more than three levels. Behind floors, walls, or ceilings with a ____ minute finish rating, ENT must be hidden:

Accepted Answer

15

Answer

NEC 362.10(2) permits Electrical Nonmetallic Tubing (ENT) to be installed in buildings exceeding three floors above grade, provided it is concealed within walls, floors, or ceilings. A critical condition for this use is that these structural elements must provide a thermal barrier with a minimum 15-minute finish rating. This requirement enhances fire safety by limiting the spread of fire and smoke in taller buildings.

Question 5

For connecting equipment or taps to luminaires, FMC Trade size 3/8 can be used in lengths no longer than :

Accepted Answer

6 ft

Answer

NEC 348.20(A)(2) provides an exception that allows 3/8 inch trade size Flexible Metal Conduit (FMC) to be used for tap conductors to luminaires or other equipment. However, this exception strictly limits the length of such applications to no more than 1.8 meters (6 feet). This ensures that while flexibility is provided for connections, the overall protection and integrity of the wiring system are maintained for these short runs.

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Free NEC Code Basic Questions and Answers