Pilot lights and indicator lights are incandescent or light emitting diode (LED) indicating lights for machines or instruments. Incandescent lights can operate on either AC or DC circuits; however, these devices are relatively inefficient, generate heat, and have shorter operating life spans than LED pilot lights. LED pilot lights require DC. If a DC circuit is not available, an LED driver can be used to supply the appropriate DC voltage and current. Indicating lights can be built into switches. Malfunction pilot lights and indicator lights can alert operators to problems with automatic equipment. Voice mail pilot lights can turn on or blink to indicate the arrival of new telephone voice mail. A dashboard indicator light or pilot light such as a brake warning light alerts a driver to vehicle conditions (parking brake is set) or problems with the vehicle (brake fluid is low). A pilot light panel provides a single area to watch for multiple conditions (on, off, malfunction).

Important specifications for pilot lights and indicator lights include electrical requirements such as voltage (6, 12, 24, 115, or 220 VDC), size (16, 22, or 30 mm), and colors. For LED pilot lights and indicator lights, common colors include white, amber, green, red, yellow and blue. Some LED pilot lights and indicator lights can change color with the polarity of the current. Mounting style (panel, PC board) is an additional consideration when selecting pilot lights and indicator lights. Letters, numbers and symbols can be applied to the lens of the pilot light or to a bezel.

Pilot lights and indicator lights are incandescent or light emitting diode (LED) indicating lights for machines or instruments. Incandescent lights can operate on either AC or DC circuits; however, these devices are relatively inefficient, generate heat, and have shorter operating life spans than LED pilot lights. LED pilot lights require DC. If a DC circuit is not available, an LED driver can be used to supply the appropriate DC voltage and current. Indicating lights can be built into switches. Malfunction pilot lights and indicator lights can alert operators to problems with automatic equipment. Voice mail pilot lights can turn on or blink to indicate the arrival of new telephone voice mail. A dashboard indicator light or pilot light such as a brake warning light alerts a driver to vehicle conditions (parking brake is set) or problems with the vehicle (brake fluid is low). A pilot light panel provides a single area to watch for multiple conditions (on, off, malfunction).

Important specifications for pilot lights and indicator lights include electrical requirements such as voltage (6, 12, 24, 115, or 220 VDC), size (16, 22, or 30 mm), and colors. For LED pilot lights and indicator lights, common colors include white, amber, green, red, yellow and blue. Some LED pilot lights and indicator lights can change color with the polarity of the current. Mounting style (panel, PC board) is an additional consideration when selecting pilot lights and indicator lights. Letters, numbers and symbols can be applied to the lens of the pilot light or to a bezel.

Pilot lights and indicator lights are designed according to NEMA standards or IEC standards. To rate LEDs for use as pilot lights and indicator lights, manufacturers state the luminous intensity in candelas, which is a function of the viewing angle. The National Electrical Manufacturers Association (NEMA) maintains NEMA ICS5, which covers pilot lights and indicator lights. The International Organization for Standardization (ISO) maintains ISO 2412 regarding the colors of indicator lights in shipbuilding, and ISO 15871 on indicator lights for container handling and grappler arm operations on industrial trucks. National Fire Protection Association (NFPA) 1901 (Standard for Automotive Fire Apparatus) covers hazard indicator lights in the driving compartment.