Deck 25: Television, Telephone, and Low-Voltage Signal Systems

Question 1

Chime transformers are listed as ____________________ because of their low voltage rating and power limitation.

Answer 1

Class 2 transformers

Question 2

On the outside of a building, position and fasten lead-in conductors so they cannot swing closer than 24 in. (600 mm) to light and power conductors having not over 250 volts between conductors; 8 ft (3.0 m) if over 250 volts between conductors.

Answer 2

False

Question 3

Chime transformers used in dwellings are generally rated ____ volts.

A) 12
B) 16
C) 20
D) 24

Answer 3

B

Question 4

Never install electrical equipment, junction boxes, or conduit boxes above a ____________________ closed-in ceiling or within a wall.

Question 5

Telephone conductors must be separated by ____________________ from light and power conductors unless the light and power conductors are in a raceway, or in Type NM cable, Type AC cable or Type UF cable.

Question 6

The article that covers cable TV wiring installations in residences is Article ____.

A) 725
B) 810
C) 820
D) none of these

Question 7

When 120-volt receptacles and TV outlets are mounted in double-gang boxes, ____ is required in the box to isolate the TV conductors from the power wiring.

A) a metal EMI shield
B) a barrier
C) double-grounding
D) double-insulation

Question 8

Which of the following rules apply to coaxial cable installations under Article 820?

A) The outer shield of the coaxial cable must be grounded close to its point of entry into the building.
B) Coaxial cables shall not be run in the same conduits or box with electric light and power conductors.
C) Do not support coaxial cables from raceways that contain electrical light and power conductors.
D) all of the above

Question 9

Residential telephone conductor installations must be made in accordance with the requirements of ____.

A) Article 800
B) Article 810
C) Article 820
D) none of the above

Question 10

The NEC _____ in a dwelling.

A) requires at least one communication outlet
B) requires one communication outlet on each floor
C) requires one communication outlet in each habitable room.
D) does not require a communication outlet

Question 11

Because TV is a low-voltage system, metallic or nonmetallic standard single-gang device boxes, 4-in. square ____________________ with a plaster ring, plaster rings only, or special mounting brackets can be installed during the rough-in stage at each likely location of a television set.

Question 12

When coaxial cables are run underground, they must be separated at least ____________________ inches from underground light and power conductors, unless either the coaxial or power cables are run in a raceway.

Question 13

Television antennas and lead-in wires are covered under Article ____.

A) 240
B) 725
C) 810
D) 820

Question 14

A ____ is described in the NEC as any electric circuit that energizes signaling equipment.

A) signaling circuit
B) code-calling system
C) signal light system
D) code circuit

Question 15

The point where the telephone company ends and the homeowner's interior wiring begins is called the ____________________.

Question 16

NEC 725.121(B) prohibits connecting transformers in ____________________ unless specifically listed for interconnection.

Question 17

Keep the antenna and lead-in conductors at least 2 in. (50 mm) from other open wiring (as in old houses) unless the other wiring is in a(n) ____________________ or cable.

Question 18

Antennas and lead-in conductors may be attached to an electric service mast if they are kept a minimum of 36 in. (900 mm) below the power conductors.

Question 19

The type of cable most often used for television signal distribution in new residences is ____.

A) 75-ohm RG6 coaxial
B) 150-ohm unshielded twisted-pair
C) 300-ohm twin-lead
D) Type FLP

Question 20

Transformers and low-voltage wiring for doorbells are classified as ____ circuits under Article 725.

A) Class 1
B) Class 2
C) Class 3
D) none of the above