Deck 20: Low-Voltage Remote Control

Question 1

Give an overview of how a relay-based low-voltage remote-control system operates.

Answer 1

A low-voltage remote-control wiring system is relay operated. The relay is controlled by a low-voltage switching system and in turn controls the power circuit connected to it. The low-voltage, split-coil relay is the heart of the low-voltage remote-control system. When the "On" coil of the relay is energized, the solenoid mechanism causes the contacts to move into the "On" position to complete the power circuit. The contacts stay in this position until the "Off " coil is energized. When this occurs, the contacts are withdrawn and the power circuit is opened. The red wire is the "On" wire; the black wire is "Off "; and the blue wire is common to the transformer.

Question 2

When are low-voltage remote-control systems advantageous?

Answer 2

Low-voltage remote control systems are chosen because of the number of switches required and when it is desired to have extensive control of the lighting. Low-voltage remote-control systems are available ranging from very simple to very complex. These systems can provide control from multiple locations, automatic timing control, handheld (wireless)controls, occupancy sensors ("On" when motion is detected)and unoccupancy sensors ("Off " with predetermined time-delay when no one is in the room), ceiling and wall mounted sensors, photocell control for security ("On" at dusk, "Off " at dawn), and programmable controls. Federally mandated energy codes are an energy standard for buildings, such as the joint publication ANSI/ASHRAE/IESNA 90.1, the most widely adopted energy standard

Question 3

A low-voltage remote-control wiring system is ____ operated.

A)resistor
B)capacitor
C)transistor
D)relay

Answer 3

D

Question 4

If control requirements are very complex or extensive, a ____ can be installed.

A)master sequencer
B)transistor
C)conventional switch
D)double relay

Question 5

In a Class 2 circuit, because the power source of the circuit is limited, ____ overcurrent protection is required.

A)fuse-based
B)circuit-breaker-based
C)no
D)minimum

Question 6

The ____ is used in an installation where several relays are mounted in one enclosure.

A)gasket relay
B)double-throw relay
C)plug-in relay
D)standard relay

Question 7

What size knockout openings can relays be mounted through? What advantage does the plug-in relay have?

Question 8

What happens to a transformer in the case of an overload?

Question 9

To install color-coded cables correctly throughout an entire installation, the wires are connected to the ____, switches, master controls, and panel, like color to like color.

A)conductor
B)relays
C)circuit
D)barrier

Question 10

The switch used in the low-voltage remote-control system is a normally open, ____, momentary contact switch.

A)double-pole, double-throw
B)single-pole, double-throw
C)single-pole, single-throw
D)double-pole, single-throw

Question 11

____ identifying the switch's functions can be prepared and inserted in the switch cover.

A)Microchips
B)Directory strips
C)LEDs
D)Relays

Question 12

The principle of operation of a master control with rectifiers is based on the fact that a rectifier permits current in ____ direction(s).

A)only one
B)two
C)at least three
D)all

Question 13

The low-voltage relay is available in ____ mounting styles.

A)one
B)two
C)three
D)four

Question 14

The switch used in the low-voltage remote-control system is approximately ____ the size of a standard single-pole switch.

A)one-sixth
B)one-fourth
C)one-third
D)one-half

Question 15

Larger conductors should be used for long runs to minimize the ____.

A)current
B)voltage drop
C)transformer ratio
D)interrupt rating

Question 16

NEC 725.136 ( A )generally ____ Class 2 circuits in the same raceway or cable as the wiring for light and power.

A)limits the number of
B)limits the voltage of
C)prohibits
D)mandates

Question 17

Switches are available in up to ____-switch combinations with features such as pilot light, lighted toggle, and key operation.

A)2
B)4
C)8
D)10

Question 18

Most low-voltage, remote-control systems are wired with ____ AWG conductors.

A)10
B)14
C)20
D)32

Question 19

Give one advantage and one disadvantage to installing low-voltage wiring in a raceway.

Question 20

To simplify connections, the conductor color-coding combinations are red-black-white, red-black-yellow-white, red-black-yellow plus an 18 AWG common ____, red-black-blue-white, and red-black-yellow-blue-white.

A)orange
B)white
C)blue
D)green