Switch Illumination


Carling Technologies offers a broad range of illuminated and non-illuminated switches. Within switch series, illumination options can include choices in lens and lamp colors, lamp circuit configurations, and illumination types. Illumination types include neon, incandescent lamps, or LED's.

Illuminated Circuit Configurations

Depending on switch series, Carling Technologies' illuminated switches can offer dependent, independent, and combination of dependent and independent lamp circuits. In a dependent lamp circuit, the lamp or lamps are powered by the same circuit that the switch is controlling; the lamp turns on when the switch is activated. In an independent lamp circuit, the lamp or lamps are powered by a voltage source not controlled by the switch action.

A combination circuit may have one dependent and one independent lamp. In this case, an independent lamp might turn on with the power source, while the dependent lamp turns on when the switch is activated. Commonly used in the transportation industry, a typical application for this type of circuit would be on a vehicle dashboard. An independent lamp would light up the individual icons or legends on the each of the dashboard switches, then a second lamp on a switch would light when it is actuated to the "ON" position.

Available illuminated circuit configurations for any specific switch series can be found on the downloadable PDF files located on the product series pages of this web site.

Neon Lamps

Neon lamps utilize a low-density gas in a sealed glass bulb. Via two small electrodes located within the bulb, a sufficiently high voltage ionizes the inert neon gas and makes it conductive. Once it's ionized, a lower voltage will keep it ionized and keep current flowing through the lamp. The light comes from the excited neon ions. Neon lamps are ballasted with external resistors to control the amount of current flowing through the lamp (.002 amps), so that the ionized gas, which has a negative resistance, won't destroy itself. Neon lamps are usually set on their side within the switch for the best viewing angle.

Neon lamps are typically used in higher voltage, 125-250 AC applications such as power switches utilizing wall current. Neon light is shifted toward the amber/red side of the color spectrum, and therefore not recommended for use with green or blue lenses, unless using more costly special neon green bulbs. Typical bulb life is 25,000 hours.

Incandescent Lamps

Incandescent lamps utilize tungsten filaments within a vacuum-sealed bulb which give off light when heated to incandescence by electric current. Incandescent lamps can be used in applications ranging up to 48Volts (AC or DC). They do not use ballasted resistors that are required for neon and LED lamps; instead individual bulbs are designed for the voltage specified.

The current draw for incandescent lamps is dependent on the volltage used:

  • Voltage Current draw
  • 3V 350 milliamps
  • 6V 200 milliamps
  • 12V 80 milliamps
  • 24V 40 milliamps
  • 48V 20 milliamps

Incandescent lamps can accommodate the full range of lens colors, including blue and green. Incandescent lamps offer dispersed beam brightness whose intensity is measured in mean squared candlepower (MSCP). They were once considered the brightest of lamp offerings, however current LED technology can now match incandescent brightness.

Typical incandescent bulb life is 10,000 - 25,000 hours, depending on voltage. Bulb life can also be adversely affected by shock and vibration, voltage swings, and temperature rise. Incandescent lamps can also be susceptible to DC notching, where current flow in one direction can cause a notch to form on the filament. This "cuts" or reduces the cross section of the filament, thus causing it to weaken and eventually cease to function.


LED's (Light Emitting Diodes) are composed of a DC diode chip and connections encased in plastic and epoxy. This encasement, which protects against shock and vibration, is one of the many reasons why LED's are considered the ideal illumination choice for the transportation industry.

At 100,000+ hours, LED lamp life is ten times that of incandescent lamps. Unlike incandescent lamps, heat rise is not a factor for LED life cycle; LED's generate only a 6 degree temperature rise above ambient, as compared to the 51 degree temperature rise of incandescent lamps. Because LED's are absent of fragile filaments, they are also not susceptible to breakage or DC notching.

LED's offer focused beam brightness (measured in millicandellas) which is able to match the light intensity of incandescent lamps. LED's are available in a wide range of colors and intensities. Certain colors such as blue and white are extremely static sensitive, and caution must be used when handling and assembling. Carling Technologies employs special ESD (static sensitive) production lines for assembling these types of illuminated switches.

Illumination Colors

Illuminated switches of all types come in a variety of colors. Depending on series and lamp type, illumination color may be accomplished via lamp or lens or both. Standard illumination colors can include amber, red, green, blue, white, and clear. Should you have special lamp or lens color needs, please contact your Carling Technologies Sales Representative for assistance.