A1-LT 11, R3-LT 1 Switches and Controls

• What is a switch?

  A controller that is used to link the load and the source. It controls current by opening or closing the circuit. It does not absorb or convert energy
• Why is it necessary for a switch to open and close quickly?


  It minimizes arcing
• What phase switch do lamps and other general devices that use 120V ac operate on?

  Single-pole switch
• What is a double pole switch?

  Controls 240V loads (phase 2)
• What are the most common types of snap switches?

  single-pole switches, three-way switch, and four-way switch
• What do snap switches control?

  Incandescent and fluorescent lamps
• Can several lamps be controlled using the same single-pole switch?

  Yes
• How does a single-pole switch operate?

  ON means handle is up, OFF means handle is down
• What is a three-way switch?

  A three-way switch is a type of electrical switch that allows you to control a light fixture from two different locations. It does not have an ON or OFF position
• What is the wire called that connects the switch to the load?

  Switch leg
• What is a four-way switch?

  A four-way switch is a type of electrical switch used in conjunction with two three-way switches to control a single light fixture from three or more different locations. It does not have an ON or OFF position. It has 4 terminals
• What is a dimmer?

  Controls light output from full brightness to zero light output
• Must a switch be manually operated?

  No
• If a load is supplied from 2 hot lines, does the switch only need to open 1 hot line?


  No, it must control both
• What ratings should switches have marked on them?

  voltage and current
• What are 3 main types of devices used to control incandescent lightning?

  snap switches, dimmer switches, and relays and contactors
• What is the most frequent device used to control incandescent lighting?

  Snap switches (and the single-pole is the most commonly used of the 3 snap switches)
• What is an example of where a 4 way switch would be used?

  A long hallway where switches are located at 3 or more locations
• What are travellers?

  Wires connecting 3-way and 4-way switch nodes
• What's a pull-type switch?

  A switch activated by pulling on a cord or chain (must be constructed of approved insulating material)
• What must be present on all dimmers?

  CEC requires an ON/OFF button
• What kind of lamps can dimmers control?

  Strictly used for incandescent lamps
• What are relays and contactors?

  Switches where an external control circuit is used to open or close the lighting circuit
• Where are relays used?

  Usually used on lower voltage/lower current (less power) than contactors
• How are extra-low voltage relays controlled?


  They use signals via electromagnets to activate switches on or off (gives momentary pulse of current, but coil does not remain energized)
• What are advantages of extra-low-voltage controls?

  -additional switches can easily be connected

  -enhances safety

  -can have inexpensive wire
• What is a lighting contactor?

  Used where a large bank of lights is required to come on at the same time. The push buttons energize or de-energize the coil of the contactor, which switches the bank of lamps on or off
• How is a contactor different from a relay?

  Contactor is usually for higher current/voltage/power and has industrial applications. They are generally larger than relays
• What must you do to ensure the single-pole switch is not energized when the switch is off?

  Have the switch open the hot wire (not the neutral)
• What kind of dimmers are required for dimmable CFL lamps?

  HED - High Efficacy Dimmers
• What is the main advantage of using a lighting contactor over a simple switch?

  Controls large bank of lights with one switch (heavier load/wattage)