Mixed Deck — All TN LLE Topics Flashcards

Per NEC 314.28(A)(2), what is the minimum distance calculation for an angle pull in a pull box with a 3-inch conduit?

Answer: 18 inches (6 x 3)

For an angle pull, NEC 314.28(A)(2) requires 6 times the trade size of the largest raceway entering that wall. 6 x 3 = 18 inches minimum, plus the sum of other raceways on the same wall.

A 10 AWG copper conductor has approximately 1.21 ohms per 1,000 feet. What is the voltage drop for a 150-foot one-way run carrying 25 amperes?

Answer: 9.08 volts

Voltage drop = 2 x Length x Resistance per foot x Current = 2 x 150 x (1.21/1000) x 25 = 9.08V.

In the NEC, what does the term "Readily Accessible" mean?

Answer: Capable of being reached quickly for operation, renewal, or inspections without requiring tools to open doors or climbing over obstacles.

Article 100 defines "Readily Accessible" as capable of being reached quickly for operation or inspection without requiring tools to open doors, climbing over obstacles, or using a portable ladder. This is a higher level of accessibility than just "Accessible."

Per NEC 210.8(A), GFCI protection is required for 125V through 250V receptacles in which dwelling unit locations?

Answer: Bathrooms, kitchens, garages, outdoors, crawl spaces, basements, and other specified locations

NEC 210.8(A) lists numerous dwelling locations requiring GFCI protection including bathrooms, garages, outdoors, crawl spaces, basements, kitchens, and several other specified areas.

What type of overcurrent protection is required for flexible cords and fixture wires per NEC 240.5?

Answer: Overcurrent protection based on NEC Table 400.5(A)(1) cord ampacity values

NEC 240.5 addresses overcurrent protection for flexible cords and fixture wires, referencing Table 400.5 for cord ampacity.

Per NEC 430.102, a motor disconnecting means must be located where relative to the motor?

Answer: Within sight from the motor location and the controller

NEC 430.102(A) and (B) require the motor disconnect to be within sight from the controller location, and 430.102(B) requires a disconnect within sight from the motor.

For a commercial building with 30 kW of general lighting load, what demand factor reduction is permitted per NEC Table 220.42?

Answer: 100% of first 12,500 VA plus 50% of remainder

Per NEC Table 220.42, commercial occupancies use 100% of the first 12,500 VA and 50% of the remainder for general lighting demand calculations.

What is the maximum rating of the feeder overcurrent protection device when supplying multiple motors per NEC 430.62?

Answer: Largest motor's branch-circuit OCPD rating plus the sum of FLCs of all other motors

NEC 430.62(A) limits the feeder OCPD to the largest motor's maximum branch-circuit protective device rating plus the sum of the full-load currents of all other motors.

An electrician is installing a 120V incandescent luminaire (lighting fixture) located 8 feet horizontally from the inside wall of a permanently installed swimming pool. According to NEC Article 680, which of the following is required for this installation?

Answer: The circuit supplying the luminaire must be protected by a Ground-Fault Circuit-Interrupter (GFCI).

According to NEC 680.22(B)(4), luminaires installed in the area extending between 5 ft and 10 ft horizontally from the inside walls of a pool must be protected by a GFCI unless they are installed at least 5 ft above the maximum water level and rigidly attached to the structure. Since the height is not specified, GFCI protection is the mandatory requirement.

What is the maximum number of 12 AWG THHN conductors permitted in a 3/4-inch EMT conduit per NEC Chapter 9?

Answer: 12

Per NEC Chapter 9, Annex C, Table C1, a 3/4-inch EMT can hold up to 12 conductors of 12 AWG THHN.

What NEC section covers series-rated systems where an upstream device protects a downstream device with a lower AIC rating?

Answer: NEC 240.86

NEC 240.86 covers series ratings, allowing a tested combination of devices where the upstream device limits fault current to protect a downstream device with a lower interrupting rating.

A feeder is protected by a 200A circuit breaker. An electrician needs to make a 10-foot feeder tap from this circuit to supply a panelboard. What is the minimum required ampacity of the tap conductors?

Answer: 10% of the feeder overcurrent device rating.

According to the 10-foot tap rule in NEC 240.21(B)(1), if the tap conductors leave the enclosure, their ampacity must be at least 10% of the rating of the overcurrent device protecting the feeder. In this case, 10% of 200A is 20A. The tap conductors must also have an ampacity not less than the calculated load and the rating of the device they terminate on.

What is the demand factor applied to the first 10 kW of commercial kitchen equipment loads per NEC Table 220.56?

Answer: Demand factor depends on number of equipment units, not a fixed kW threshold

NEC Table 220.56 provides demand factors for commercial kitchen equipment based on the number of units, not a fixed kW threshold.

What condition can cause a three-phase motor to overheat even when total current appears normal?

Answer: Voltage imbalance between the three phases

Voltage imbalance between phases causes unequal current distribution in motor windings, leading to hot spots and overheating even when average current appears normal.

NEC 300.3(B) requires that all conductors of the same circuit — including the grounded conductor and equipment grounding conductor — must be:

Answer: Contained within the same raceway, cable, or run together as a group

NEC 300.3(B) requires all conductors of the same circuit to be contained within the same cable or raceway to prevent inductive heating in metal enclosures.

An electrical enclosure is to be installed outdoors, exposed to rain and sleet. Which NEMA enclosure type is the minimum requirement for this location?

Answer: Type 3R

A NEMA Type 3R enclosure is constructed for either indoor or outdoor use to provide a degree of protection against ingress of solid foreign objects (falling dirt) and water (rain, sleet, snow). It is a common choice for residential service equipment and outdoor disconnects.

Per NEC 310.15(B)(7), what ampacity method applies to 120/240V, single-phase dwelling service conductors?

Answer: A special table with higher ampacities for service entrance conductors

NEC 310.15(B)(7) provides a special table with higher ampacities specifically for dwelling unit service and feeder conductors because of the diversity of residential loads.

Per NEC 240.86, what is the maximum distance for a series-rated system where the line-side device protects load-side devices?

Answer: No distance limit as long as the combination is tested and listed

NEC 240.86 does not impose a specific distance limit. The series combination must be tested and listed by a testing laboratory.

Per NEC 430.22, what is the minimum conductor ampacity for a single motor branch circuit?

Answer: 125% of motor FLC

NEC 430.22(A) requires branch-circuit conductors supplying a single motor to have an ampacity of not less than 125% of the motor full-load current from the applicable table.

What color wire is typically used for grounding in residential wiring?

Answer: Green or bare copper

In residential wiring, the color green or bare copper is typically used for grounding wires. The grounding wire provides a safe path for fault currents to return to the electrical panel and then to the earth, preventing dangerous voltage buildup on metal parts of appliances or fixtures. This is a critical safety feature to protect against electrical shock.