IEC 60073 fixes a small, closed palette of seven color codes for pushbutton actuators, illuminated pushbuttons, and pilot lights used on industrial machinery: RED, YELLOW (AMBER), GREEN, BLUE, WHITE, GREY, and BLACK [S1][S2]. Each color carries a defined operational meaning, and the standard explicitly forbids mixing those meanings; for example, GREEN is not permitted on a STOP/OFF actuator, and RED is not permitted on a START/ON actuator [S1][S2].
The standard applies to single indicator lights, push buttons, mechanical indicators, and LED or video display screens used to communicate the safety state of personnel and property, the condition of a process, and the state of equipment [S2]. A parallel U.S. reference is NFPA 79 (Industrial Machinery), which uses the same color-to-function mapping on machine tool and process panels [S5]. For a quick primer on the pushbutton and pilot light hardware itself, the encyclopedia page covers actuator types, contact blocks, and lens modules.
Color-to-function mapping under IEC 60073
RED is the dominant signal and is reserved for danger, emergency, and a faulty condition. Emergency-stop and emergency-OFF actuators must be identified by the color red; if red is not available, another reliably identifiable means must be substituted [S1]. When the same actuator covers both emergency stop and normal stop, the color must remain red [S1]. NFPA 79 extends this to illuminated pushbuttons: where a machine is stalled because of an overload, the button should stay red even when unlit, so the function is recognizable with the lamp failed [S5].
YELLOW (AMBER) signals warning, caution, or an abnormal condition. It is used for pushbuttons that return a machine to a safe position, suppress an abnormal state, or override a previously selected function [S1][S5]. On pilot lights, amber warns of an approaching limit, a pending change of state, or a ground fault; a permitted overload approaching its time limit is a typical case [S5].
GREEN means safe, normal, or start/on. It is permitted on START/ON actuators and on pilot lights indicating that the machine is ready or a safe condition has been authorized [S1][S2][S5]. GREEN is not permitted on STOP/OFF actuators under IEC 60073; if a designer needs to differentiate stop from start with the same family of color caps, the standard routes the user to WHITE for start/on and BLACK for stop/off [S1].
BLUE is reserved for mandatory action or a signal of significance, and is also permitted on RESET actuators (along with white, grey, and black) [S1][S2]. WHITE, GREY, and BLACK carry no specific safety meaning and are the default choice for STOP/OFF (preferred BLACK), START/ON (preferred WHITE), and any function not covered by red/yellow/green/blue, including inching and jogging [S1][S5].
Three illumination modes for indicator lamps
IEC 60073 categorizes illuminating actuators into three indication modes: alerting, indication, and confirmation, and groups illuminated devices into three lamp-behavior types [S1][S2]. Type a keeps the same color whether lit or unlit, used for plain indication. Type b shows a single color when lit that differs from the unlit color, and both colors carry meaning, which is the typical confirmation pattern for start/stop pushbuttons. Type c can display more than one lit color, used for multi-state alarms driven by the PLC [S2][S7].
For an illuminated push button driven by PLC logic, the LED is typically mapped to temperature bands, maintenance intervals, communication health, and layered alarm states, so the same lens can present three or more colors over the equipment's life cycle [S7]. In practice this means the engineer chooses Type c devices when amber-to-red escalation is required and Type b when the function is binary.
Comparison of the seven IEC 60073 colors by decision criteria
Below is a side-by-side of the seven IEC 60073 colors against four decision criteria an engineer applies when specifying a button or lamp. [S1]
RED: meaning, emergency stop / danger; allowed on actuators, yes (mandatory for E-stop); allowed on pilot lights, yes; typical use, emergency stop, master stop, protective-device tripped [S1][S2][S5].
YELLOW (AMBER): meaning, warning / abnormal; allowed on actuators, yes; allowed on pilot lights, yes; typical use, return-to-safe, override, limit approaching [S1][S2][S5].
GREEN: meaning, safe / normal / start-on; allowed on actuators, yes (start only); allowed on pilot lights, yes; typical use, machine ready, authorization to proceed [S1][S2][S5].
BLUE: meaning, mandatory action / significance / reset; allowed on actuators, yes (reset); allowed on pilot lights, yes; typical use, reset, mandatory action such as a required operator input [S1][S2].
WHITE: meaning, no specific meaning (preferred for start/on); allowed on actuators, yes; allowed on pilot lights, yes (commonly used for circuit-energized confirmation); typical use, start/on in white/black pairing [S1][S5].
GREY: meaning, no specific meaning; allowed on actuators, yes; allowed on pilot lights, yes; typical use, generic stop/off or start/on when white is reserved [S1].
BLACK: meaning, no specific meaning (preferred for stop/off); allowed on actuators, yes (not the sole-function stop/off button); allowed on pilot lights, rarely; typical use, stop/off in white/black pairing, inch/jog [S1][S5].
Common specification mistakes and constraints
Three pitfalls show up repeatedly on retrofit panels. First, putting a green lens on a stop button: the IEC text is explicit that green is not permitted on a STOP/OFF actuator, so a green cap on a stop button fails a CE/IEC 60073 audit even if the wiring is correct [S1][S2]. Second, relying on lamp color alone for an emergency-stop function: the red identification of an emergency-stop actuator must not depend on the illumination of its light, so the unlit color of an E-stop lens must still read as red [S5]. Third, using red on a start button: red is not permitted on a START/ON actuator under IEC 60073, and NFPA 79 carries the same rule [S1][S5].
For sound, the same standard maps acoustic patterns to meaning: a sweeping or burst signal reads as danger/emergency, a constant-level pattern as warning/caution, a continuous steady tone as safe/normal, and an alternating pitch as mandatory action [S2]. Pairing an acoustic channel with the visual color is how an IEC 60073-compliant panel achieves redundancy for noisy or dimly lit stations.
Where IEC 60073 stops and other codes take over
IEC 60073 governs the meaning of colors, shapes, and acoustic signals on indicators and actuators. It does not define safety signage on equipment guards, floors, or pipes; that role belongs to ISO 3864 and the related safety-sign standards, which carry their own red/yellow/green/blue conventions that overlap but are not identical [S3][S6]. On the electrical safety side, an E-stop device that uses IEC 60073 color coding is normally paired with a switch element built to IEC 60947-5-1 or IEC 60947-5-5; the switching-distance and proxied-sensor rules in IEC 60947-5-2 Sn/Sr/Sa logic do not apply to the colored actuator itself but do apply to the proximity sensors commonly used in the same panel. For an actuator wired through a safety relay or contact block, the safety-rated contacts sit under IEC 60947-5-1, while the colored lens cap stays under IEC 60073.
Engineers specifying illuminated pushbuttons in 2026 should also note the dominant hardware shift: LED-illuminated units are now reported to exceed 70% of new industrial orders, with LED lamp life around 50,000 hours versus 2,000-5,000 hours for incandescent and 10,000-25,000 hours for neon, which removes lamp-replacement as a maintenance line item on most panels [S4]. The IEC 60073 color rules apply identically across LED, incandescent, and neon sources; the source does not change the meaning.
Two trackable signals to watch through the rest of 2026: (1) any harmonization update between IEC 60073 and ISO 3864 on the blue-for-mandatory-action meaning, which both codes carry but with different scope, and (2) wider adoption of Type c multi-color illuminated pushbuttons driven by PLC logic, which compresses three discrete indicator lamps (red, amber, green) into a single 22 mm panel cutout [S3][S7].
Detailed specification references: color mark sensor, and pressure transmitter.