22 mm Panel Indicator Lamp · Field Selection Guide

AD16-22/22
Indicator Lamp Technical Quick Reference

AD16 series Φ22 mm panel-mount signal lamps (indicator lamps, power indicator lamps, sound-and-light signal lamps). This quick-reference sheet consolidates voltage ratings, AC/DC compatibility, color semantics and application pairing with adjacent equipment into a single page, so the correct part number can be confirmed in 30 seconds, before you order.

Mounting hole

Φ22 mm

Voltage span

6–500 V

Colors

6 + bi/tri-color

Rated operating current

≤ 20 mA

Head protection

IP40 → IP65/67

Continuous working life

30,000–50,000 h

Reading the part number

AD16-22/22 is a shortened form widely used by sellers. Break the part number apart and each position tells you one thing: where it mounts, what shape it is, what color it is, what voltage it takes, and what protection level it carries.

AD16-22/22

The designation you received

AD16-22/D/R/24V

General ordering format (example)

AD16Series code. AD16 is the high-brightness single-colour LED indicator series, the upgraded replacement for XD incandescent and neon indicators; 16 is an internal structural number and does not denote the hole diameter.

22Basic specification code — the mounting hole diameter, Φ22 mm. With a reducing ring it also fits Φ25 mm / Φ30 mm panels, one of the most widely used panel cut-outs.

D / C / B…Auxiliary code (outline and function). Different shapes sharing the same neck size: D round flat, C round, B square, etc.; also M buzzer, S flashing, SM sound-and-light, SS bi-color, P position indicator.

R / G / YColor code. r red, g green, y yellow, b blue, w white, o orange; bi-color lamps use a two-color combination (e.g. rb).

24V / 220VVoltage code. The two digits are the nominal voltage and determine the voltage-dropper type (resistive = AC/DC universal, capacitive = AC only).

K / F / PAdditional codes. K anti-interference, F for capacitor cabinet discharge, P for IP65 front head; no letter means the standard IP40 type.

On "/22": in the "AD16-22/22" you receive, the second 22 does not mean the same thing across manufacturers (most often the 22 mm head/hole, sometimes simply a series shorthand). Do not write only "AD16-22/22" on a purchase order — complete it to the full designation "series-hole / shape / color / voltage / protection" per the manufacturer catalog, otherwise one order may arrive with round-flat or square bodies, or without the IP65 option.

Product positioning

Applicable to power, telecommunications, machine-tool, marine, textile, printing and rail-transit circuits in AC 50 Hz (or 60 Hz) up to 500 V and AC/DC up to 500 V, used as signal indication, warning indication and accident signaling wherever light is used as the means of indication.

Structural highlights

High-brightness single-colour LED chips — true colour, low power draw
Lens in high-strength polycarbonate — impact resistant, good insulation
Built-in screw terminals for a high safety factor
Text and symbols can be laser-etched or screen-printed
Nut-locking panel mount, suits 1–6 mm panel thickness

Where selection most often goes wrong

AC and AC/DC versions have different internal circuits — not interchangeable in the same housing
Marketplace listings often state color only, omitting voltage
The IP40 base type is unsuitable for outdoor or wash-down duty
Standard types must not be used in explosive gas atmospheres
Mis-wiring an AC bi-color lamp destroys it

Available voltages · Is AC/DC universal?

Straight answer: the low and mid range (6–48 V) is mostly available as AC/DC universal; above 110 V you must confirm whether the part is universal or AC-only. Universal never means "any voltage will do".

Voltage code	Nominal voltage	Supply type	Dropper type	Rated current	Frequency	Typical use
21	AC/DC 6 V	Universal	ResistiveAccepts 6 V DC or 6 V mains AC	15 / 25 / 35 mAVaries with color	50–60 Hz	Low-voltage control circuits, small sensors, PLC signals
22	12 V	Universal	Resistive	15 mA	50–60 Hz	Automotive/instrument, 24 V system applications, relay signals
23	24 V	Universal	Resistive	15 mA	50–60 Hz	Most common: PLC, VFD, machine tools, EV-charger control signals
24	36 V	Universal	Resistive	15 mA	50–60 Hz	Certain machine tools and mining equipment control circuits
25	48 V	Universal	Resistive	15 mA	50–60 Hz	Telecom power, PV combiner boxes, 48 V DC systems
26	110 V	Universal	Resistive	15 mA	50–60 Hz	110 V industrial network status indication
27	127 V	Universal	Resistive	15 mA	50–60 Hz	Mining and some industrial network voltages
28	AC/DC 220 V	Universal	ResistiveHousing temperature rise exceeds the AC type above 110 V	10 mA	50–60 Hz	220 V distribution panel indication, covers both DC and AC sites
29	380 V	FD dedicated	Capacitor cabinet discharge type	10 mA	50–60 Hz	Capacitor cabinet door indication, live-bus indication inside
30	AC 500 V	AC only	Capacitive	8 mA	50–60 Hz	HV switchgear phase sequence and live indication
31	AC 220 V	AC only	Capacitive	15 mA	50–60 Hz	Mains 220 V motor and circuit running indication (lowest cost)
32	AC 380 V	AC only	Capacitive	18 mA	50–60 Hz	Three-phase 380 V motor running indication, main switchgear panels

Some manufacturers also offer 380 V as an AC/DC universal (resistive) type — but their catalogs state explicitly that above 110 V the housing temperature rise of the AC/DC universal type exceeds that of the AC type, so long-term full load poses a risk of overheating. For 220 V/380 V main circuit indication, prefer the AC-only type (capacitive dropper).

Verdict 01

Universality has conditions

"AC/DC universal" means that at the same nominal voltage the lamp lights on both AC and DC, which covers 6–48 V and part of the 110/220 V range. It does not mean a 220 V AC lamp can run on 24 V, or that a 24 V lamp can run on 220 V.

Verdict 02

Two different dropper circuits

The AC/DC type uses a resistive dropper, the AC type a capacitive one. At the same nominal voltage the circuit, housing and heat output all differ, so you cannot "keep the housing and swap the lamp core". The AC type works only at 50/60 Hz — other frequencies will destroy it.

Verdict 03

Configuring DC systems

Where the equipment runs on a DC bus (24 V / 48 V / 110 V DC), choose an AC/DC universal type rated for DC, so one lamp serves both the DC control circuit and mains testing during maintenance. AC tolerates ± 20 % voltage fluctuation (above 110 V).

Available colors · Where each is used

Click any color card and the lamp above switches to that color in real time. Color semantics follow the IEC 60073 / GB/T 4025 conventions, combined with how electrical practice actually reads them on site.

Currently selected

Red R

Semantics: danger, fault, stop. Live, alarmed, the resting state after an emergency stop.

Red R

R / r

Semantics: danger, fault, stop. Live, alarmed, the resting state after an emergency stop.

Equipment fault and alarm indication
Status lamp after the emergency stop is pressed
"Live / energized" warning on distribution panels
Abnormal indication on fire and safety circuits

Note: on some Chinese sites red also means "machine running". If green is already taken on the same panel, state the meaning on the drawing and silkscreen — otherwise misreading at shift change is almost guaranteed.

Green G

G / g

Semantics: normal, running, ready. The equipment is in its expected working state.

Motor, fan and pump running indication
Power healthy, system ready, start permitted
Safety circuit closed, access control and earthing healthy
Charger connected and idle, UPS on mains

Standard practice: green = run/normal, red = fault/stop, yellow = warning/standby, blue = special function. Never use green to mean "danger".

Yellow Y

Y / y

Semantics: warning, caution, standby. Not yet a fault, but someone must look.

Standby, ready, remote or manual mode
Low level, low pressure, filter due for change
Parameter out of limits, temperature rise warning
UPS on bypass, running on battery

A flashing yellow usually means "alarm awaiting acknowledgement" and pairs with a buzzer or the flashing (S) type; a steady yellow means "standby, not running".

Blue B

B / b

Semantics: auxiliary, special function. Neutral information — neither normal nor dangerous.

Program running, automatic/manual mode indication
VFD running, motor regeneration / feedback state
Charging, link online, data uploading
Position indicator (isolator open/closed, earthing)

Blue is an information color — do not use it for faults. If a plant standardizes on blue = running, label it explicitly on the silkscreen to avoid confusion with green.

White W

W / w

Semantics: neutral information, power present. Indicates a state with no safety judgment attached.

Panel interior lighting, general panel illumination
Circuit live, power available indication
Circuit numbering in multi-circuit panels
Open/closed position indication (with D/N/G codes)

White lamps read poorly in bright ambient light. Do not let a white lamp carry a critical state on its own — pair it with position marks or text.

Orange O

O / o

Semantics: a special mark between yellow and red, usually custom-made.

Vendor-defined states (e.g. "filling", "changing material")
Dedicated marking of a special process step
Alignment with an existing customer HMI color standard

Orange and yellow are easily confused for color-deficient users or in bright light. Where yellow is already widespread on site, distinguish the orange lamps by adding a distinct shape or a text label.

Extended lamp types: besides the six basic colors the range also offers bi-color lamps (SS) — e.g. red/green for on/off or fault/run; tri-color lamps (R/G/Y) for stop/run/warning; flashing lamps (S) for alarms; and sound-and-light types (SM) with a buzzer (up to 80 dB at 10 cm) for noisy environments. Their color combinations must follow the same semantic rules — never let both colors of a bi-color lamp mean "normal".

Application pairing with adjacent equipment

The same lamp can demand a different color and voltage for the same position in different industries. Below, the common equipment is matched line by line.

⚡

Switchgear & distribution

switchgear

Incoming line / busbar energized warningHazard marking — do not touchAC 220 V · red · steady
HV panel phase sequence / live indicationThe 500 V version connects directly across the main busAC 380–500 V · red · dedicated
Earthing switch closedPosition indicator with D/N/G codesAC 220 V · green
Panel interior lightingGeneral illumination, carries no statusAC/DC 220 V · white
SPD degradation monitoringAuxiliary signalAC/DC 24 V · blue

⚙

Machine tools & automation

machine tool

Spindle / motor runningThe canonical "green = running"AC 380 V / 24 V · green
Alarm / after emergency-stop resetRed flashing paired with a buzzer24 V · red · sound-and-light
Servo / system standbyNeither faulted nor running24 V · yellow
Automatic mode / program executingSpecial-function state24 V · blue
Low lubrication pressure / low coolant levelWarning, not yet an alarm24 V · yellow

☀

Renewables & charging

energy

Charging gun connected / readyCharging may begin24 V DC · green
Charging in progressProcess state uses the information color24 V DC · blue
Insulation fault / comms lossRequires a shutdown24 V DC · red · flashing
PV inverter grid-tied and runningGrid-tied = normal48 V / 220 V · green
Storage SOC low / on battery bypassAlarming but still running48 V DC · yellow

🏢

Buildings & HVAC

hvac

Pump / fan runningMotor running indicationAC 220 V / 380 V · green
Pump fault / phase lossShutdown / fault class — shown in red24 V · red
Low level / pressure warningYellow first, red later24 V · yellow
Elevator running / leveledRequired by fire code24 V DC · green
Maintenance mode / door openPersonnel are intervening24 V DC · yellow · flashing

⚓

Transport & marine

transport

Train battery supplyDC systemDC 110 V · blue
Platform / vehicle doors closedMovement permitted24 V DC · green
Main engine running / steering gear failureMarine engine-room conventionAC 220 V / 24 V · red
Engine-room alarmPaired with the buzzer24 V · yellow · sound-and-light

🧪

Chemicals & electrolysis

process

Rectifier unit runningHigh-current output working stateAC 380 V · green
Polarization voltage / cell voltage displayA separate information channelAC 380 V · blue
Rectifier fault shutdownShutdown class of red24 V · red
Circulation / cooling pump on standbyTransitional state24 V · yellow

🖥

Data center & logistics

datacenter

UPS on mainsDual incoming supply indicationAC 220 V · green
UPS on bypass / on batteryDegraded operation24 V · yellow
Server / air conditioner runningRunning state24 V · green
AGV charging / link onlineProcess and information24 V DC · blue
Forklift / AGV battery lowTime to swap the battery24 V DC · yellow

🧯

Fire & safety

fire & safety

Fire power supply healthyA color fixed by regulationAC 220 V · green
Fire alarm control panel alarmSound and light together24 V · red · sound-and-light
Manual call point pressed / hydrant pressure lowSignal for human intervention24 V · yellow
Safety circuit closedOperation permitted24 V · green

Compliance note: in fire, elevator, marine and rail sectors, indicator colors and mounting arrangements are often mandated by regulation or industry standard (for example, fire power indication must be green). Where safety or statutory judgment is involved, follow the applicable standard and fire-inspection requirements — AD16 only provides the physical means of indication. In explosive gas atmospheres, choose an intrinsically safe (Ex ia) or flameproof (Ex d) certified product; a standard AD16-22 is not suitable.

Selection in six steps

Click through each step to confirm the key points; the progress bar records what you have already verified. Once all are ticked, the part number is essentially settled.

Confirm installation conditionsPanel cut-out and thickness

Standard cut-out Φ22 mm (catalog tolerance Φ22.2 +0.5/−0.0 mm); reducing rings cover Φ25 mm / Φ30 mm. Typically suits 1–6 mm panels, with a threaded barrel and lock nut. Tighten to 1.5–2.0 N·m — overtightening can crack the plastic housing.

Φ22 mmΦ25 / Φ30 with ringPanel 1–6 mm

Determine the supplyAC or DC bus

First establish whether the circuit being indicated is mains AC or a DC bus, then note the voltage. For 6–48 V prefer an AC/DC universal type — one lamp works on the DC control circuit and on mains for testing. For 220 V/380 V main circuits prefer the AC-only type, to avoid the higher housing temperature rise of a resistive type.

DC bus → AC/DC universalMains circuit → AC only50–60 Hz only

Match color semanticsKeep consistent with the other lamps on the panel

Color meaning must be consistent within one system: green = normal/running, red = fault/stop, yellow = warning/standby, blue = special function, white = neutral/energized. If another color is already taken on the panel, confirm with the site whether the existing convention is kept before deciding on orange or a bi-color lamp.

Green normalRed faultYellow warningBlue specialWhite neutral

Choose the lamp typeSteady / flashing / bi-color / sound-and-light / position

A steady type is enough for a single state. For alarms that must grab attention use the flashing type (S) or sound-and-light type (SM). To distinguish two or three states use bi-color (SS) or tri-color lamps. For switchgear position indication use the P series with G/D/N codes. In noisy areas prefer sound-and-light — buzzer output reaches 80 dB at 10 cm.

SteadyS flashingSM sound-and-lightSS bi-colorP position

Verify protection levelDriven by the installation environment

The base head is IP40 and suits indoor control panels. Outdoors, in dust, where wash-down is needed, or mounted outside a machine, choose the P code for IP65 or order the IP67 version; some round heads reach IP65 directly. Standard types are not permitted in hazardous areas — select an Ex-certified product.

IP40 indoorIP65 outdoor/wash-downIP67 to orderEx intrinsically safe

Check electrical margin and wiringThe last mile

AC tolerates ± 20 % voltage fluctuation (above 110 V). On the DC side allow 15–20 % margin so a bus dip is not misread as a lamp failure. Wire with screw terminals, 0.5–2.5 mm²; prefer the plug-in connector (2.5 × 0.8 mm) to soldering — if soldering is unavoidable, use an iron below 30 W for no more than 3 seconds, and do not stress the terminal.

AC ± 20 %DC margin 15–20 %0.5–2.5mm²Screw terminal

0 / 6 confirmed

Main technical specifications

Compiled from manufacturer catalogs and CCC certification documents. Values differ slightly between manufacturers — confirm against the sample supplied with the goods before ordering.

Electrical & environmental

Rated operating frequencyAC 50 / 60 Hz

Rated operating current≤ 20 mA

Power consumption≤ 0.5–1.5 W (depends on voltage)

Power-frequency dielectric withstand voltage2.5 kV (AC rms), 1 min

Rated impulse voltage Uimp2.5 kV

Insulation resistance≥ 2 MΩ (≥ 5 MΩ when Ui ≤ 60 V)

Comparative tracking index (CTI)≥ 100 (some catalogs ≥ 175)

Rated insulation voltage Ui500 V

Luminance≥ 100 cd/m²

Continuous working life≥ 30,000 h (some ≥ 40,000/50,000 h)

Operating temperature−25 °C to +55 °C

Relative humidity≤ 98 %

Altitude≤ 2000 m

Vibration2–80 Hz / 0.7 g, operating normally

Pollution degree / installation category3 / III

Mechanical & installation

Mounting holeΦ22.2 mm (+0.5 / −0.0 mm)

Panel thickness1–6 mm

Mounting methodNut-locking panel mount

Tightening torque1.5–2.0 N·m

Terminal typeScrew or flat-tab (lug) terminal (0.5–2.5 mm²)

Head protectionIP40 (base) · IP54 · IP65 · IP67

Cut-out expansionReducing ring → Φ25 / Φ30 mm

Housing materialFlame-retardant engineering plastic + polycarbonate lens

Overall protection (complete product)IP65 / IP67 (some structures)

Mechanical life≥ 100,000 operations

Anti-interference typeCode K (interference-suppression type, limiting value generally ≤ 40 V)

StandardsIEC 60947-5-1 · GB standards · RoHS · CCC / CE

Marking optionsCustom text, symbols, color combinations

Industries servedPower · Telecom · Machine tools · Marine · Textile · Printing · Rail transit

Pre-order checklist

A fully specified order avoids almost every "it arrived wrong" rework. Tick the items before sending the requisition.

✓

Does the full part number include voltage and color Marketplace listings often say only "red 22 mm indicator light" without a voltage code, so the mismatch surfaces at goods-in. Specify: AD16-22 / D / R / 24V.

✓

Is the supply type stated "AC/DC universal" and "AC only" are different products and must appear on the order or spec sheet.

✓

Do not mix AC and DC versions in the 220 V band The internal dropper differs; the housings may look identical but are not interchangeable.

✓

Above 110 V, is a pure AC type chosen If a resistive AC/DC type is used, confirm the temperature rise is acceptable.

✓

Does the protection level suit the environment Outdoor and wash-down duty requires the P code (IP65); the IP40 base type fails quickly once water gets in.

✓

Is the anti-interference type (K) needed In circuits with strong interference near VFDs and high-power motors, use code K where needed.

✓

Is custom text or a symbol required Lens silkscreen or laser marking needs the content, size and position written into the order remarks.

✓

Color sequence for bi-color / tri-color lamps For "red-green bi-color", state which color lights in which state.

✓

Quantity and spares Order 5–10 % extra from the same batch so a single replacement does not create a color mismatch on the panel.