Deck 8: Article 725 of the National Electrical Code; Classification of Circuits

Question 1

Class 2 circuit conductors shall be insulated to a maximum of _________.

A) 30V
B) 90V
C) 100V
D) 150V

Answer 1

D

Question 2

Pipe fill is required for which of the following circuits?

A) Security Alarm circuits
B) Telephone circuits
C) Audio circuits
D) Computer Networking circuits

Answer 2

C

Question 3

Instrumentation tray cable can be used as a substitute for Class 3 wiring.

Answer 3

False

Question 4

Multiple Class 2 or Class 3 power supplies can be wired in parallel with each other.

Question 5

Class 2 circuits may be installed in the same enclosure or cable with conductors of Class 3 circuits provided _________.

A) Circuit voltages are not above 150V
B) They are functionally associated
C) The class 2 conductors are insulated to a minimum of 300V
D) The class 2 and Class 3 conductors are insulated to a minimum of 600V

Question 6

All Class 2 conductors may be strapped or attached to the exterior of a conduit.

Question 7

Exterior run Class 2 and Class 3 circuits must maintain a minimum separation of _________ from Class 1 electric light and power circuits.

A) ¼ inch
B) 1 inch
C) 2 inch
D) 6 inch

Question 8

Insulation requirements for Class 1 conductors 18 and 16 AWG must be suitable for 600 V.

Question 9

Class 2 or Class 3 conductors may be run in the same raceway with Class 1 circuits provided _________.

A) They are functionally associated
B) They are separated by a solid and firmly fixed barrier
C) That there is a 2 inch separation between the conductors
D) They are carrying less than 150V

Question 10

Class 1 circuits, that are not functionally associated, must be separated from power conductors by a solid and firmly fixed barrier.

Question 11

Power sources for Class 2 or Class 3 circuits may be derived from ________.

A) A listed or labeled Class 2 or Class 3 power supply or transformer
B) Any inherently limited power supply
C) Any power supply having a maximum output of 100VA
D) Any power supply 150V or less

Question 12

Class 3 power supplies may operate up to a maximum of 1000VA.

Question 13

Class 2 or Class 3 conductors may be installed within enclosures including electric light and power circuits provided _________.

A) The Class 2 and Class 3 circuits are installed as Class 3 and they maintain ¼" separation
B) They are installed as Class 1 circuits
C) The Class 1 circuits are functionally associated and maintain ¼' separation
D) All the above

Question 14

A Power-limited Class 1 circuit may operate at a maximum of _________.

A) 600V, 1000VA
B) 30V, 1000VA
C) 150V, 1000VA
D) 30V, 100VA

Question 15

Signaling circuits include _________.

A) Circuits that activate notification devices
B) Circuits that signal other circuits
C) Circuits that control other circuits
D) Communication circuits

Question 16

If an equipment failure were to introduce a direct life or fire hazard, the circuit must be reclassified as Class 1.

Question 17

The overcurrent protection device for a Class 1 circuits may be rated to _________.

A) 70% of the power supply rating
B) 100% of the power supply rating
C) 167% of the power supply rating
D) 200% of the power supply rating

Question 18

Coaxial cable connecting a video camera to a monitor is an example of integral wiring.

Question 19

Class 3 conductor may be smaller than 18 AWG.

Question 20

Class 1 circuits typically operate from greater voltage and current levels than those of Class 2 or 3 circuits.

Question 21

You have a Rigid PVC conduit (RNC), schedule 80, that is required to hold the following conductors; six -18AWG TFN, ten -18AWG XFF and four -16AWG XF.   Answer the questions below.
Calculate the total diameter of the TFN conductors.

Question 22

Class 2 or Class 3 audio circuit conductors in accordance with section 640.9 of the NEC, __________ occupy the same cable or raceway with other Class 2 or Class 3 remote control or signaling circuits.

A) Shall not be permitted to
B) Shall
C) Shall be permitted to
D) Must

Question 23

Class 2 AC power supplies between 30V-150V may operate at a maximum of __________.

A) 5mA
B) 50mA
C) 500mA
D) They are not allowed to operate above 30V

Question 24

You have a Rigid PVC conduit (RNC), schedule 80, that is required to hold the following conductors; six -18AWG TFN, ten -18AWG XFF and four -16AWG XF.   Answer the questions below.
What percentage fill is required by the NEC ?

Question 25

The rating on power-limited tray cable should be rated for_____ V and not less than _______ AWG.

A) 150V, 18AWG
B) 150V, 22AWG
C) 300V, 18AWG
D) 300V, 22 AWG

Question 26

You have a Rigid PVC conduit (RNC), schedule 80, that is required to hold the following conductors; six -18AWG TFN, ten -18AWG XFF and four -16AWG XF.   Answer the questions below.
What size RNC is needed to accommodate the conductors?

Question 27

You have a Rigid PVC conduit (RNC), schedule 80, that is required to hold the following conductors; six -18AWG TFN, ten -18AWG XFF and four -16AWG XF.   Answer the questions below.
​ Calculate the total diameter of the XFF conductors.

Question 28

In elevators, power-limited circuits must be installed __________.

A) To maintain a 2 inch separation form class 1 circuits
B) Inside a rigid metal conduit or non-metallic conduit
C) As class 1 wiring
D) In a cable tray

Question 29

A power-limited Class 3 power supply must never exceed _________.

A) 30V, 100VA
B) 150V, 100VA
C) 300V, 100VA
D) 600V, 1000VA

Question 30

You have a Rigid PVC conduit (RNC), schedule 80, that is required to hold the following conductors; six -18AWG TFN, ten -18AWG XFF and four -16AWG XF.   Answer the questions below.
Calculate the total diameter of the XF conductors.