5-Pin Push Button Wiring: COM, NO, NC and LED

A common five-pin illuminated button contains two separate circuits: one changeover contact and one lamp. The pin positions are model-specific. Start with the exact terminal drawing, not the appearance of the rear connections.

Identify the contact and lamp terminals.

COM is the common contact. NO is open to COM when the button is unoperated; NC is closed. The two lamp terminals have their own voltage and AC/DC requirements. Follow any polarity markings and confirm whether the mechanism is momentary or latching.

Read the low-voltage example.

The diagram uses an isolated, protected 24V DC supply, a 24V DC-rated LED assembly and a small compatible DC indicator load. It shows circuit functions, not physical pin locations. It is not a motor or emergency-stop circuit.

With the supply isolated, the protected positive feed goes to COM, NO supplies the load, and the load returns to 0V. The rated lamp connects between NO and 0V so that it lights with the switched output. NC remains unconnected and protected. Combined load and lamp current must stay within the contact rating.

Check the intended behaviour.

A momentary button returns when released; a push-on/push-off mechanism retains its contact state until the next operation. Connecting the lamp directly across the supply instead makes it a power indication. An NC contact alone does not provide a validated safety function.

Inspect before applying power.

Verify the model diagram, lamp rating, circuit protection and terminations. Check continuity only with the circuit isolated and disconnected. If operation is wrong, isolate the supply and recheck terminal identity and polarity; do not try a higher voltage.

Choosing for your application? Send the load details, operating action and LED voltage. Browse metal push buttons → or request the exact terminal drawing. Industrial loads may require a suitably designed relay or controller interface.

Original 12V DC COM / NO / NC / LED diagram

This second example uses an isolated, protected 12V DC supply, a complete 12V DC-rated LED assembly and a small compatible 12V DC indicator load. It shows an SPDT changeover contact plus a separate lamp. It is not a universal rear-view pinout.

Five-terminal function check — isolated circuit

Terminal	Released	Pressed
COM	Connected to NC.	Connected to NO.
NO	Open to COM.	Closed to COM; supplies the example load and lamp.
NC	Closed to COM; unused and insulated in this example.	Open to COM.
LED + / LED −	Separate lamp circuit; off in this switched-output example.	12V-rated lamp operates from NO to 0V; follow any polarity markings.

Do not connect a bare LED directly to the supply: this example requires a complete voltage-rated lamp assembly. A 12V example requires 12V-rated components; changing the supply to 24V is not a troubleshooting step. Any wiring work must be performed with the supply isolated. The load plus lamp current must remain within the applicable DC contact rating, including the load type and inrush.

Troubleshooting before reconnecting power

Five-pin wiring fault checks

Symptom	Likely item to check	Safe next step
Lamp on all the time	Lamp may be across the supply rather than the switched NO output.	Isolate the supply and compare the intended lamp behaviour with the diagram.
Load on when released	The load may be on NC, or the mechanism may be latching.	With the circuit isolated and disconnected, check the terminal drawing and continuity.
Load switches but lamp stays dark	Lamp voltage/type, connection or polarity may be wrong.	Confirm the ordered lamp rating and polarity; never increase voltage to test it.
Neither lamp nor load operates	Open protection device, missing return or wrong common terminal.	Isolate and inspect the wiring; determine the cause before replacing protection.
Unexpected heating or repeated fuse operation	Short circuit, unsuitable load/inrush, loose termination or wrong rating.	Stop using the circuit and have the design and wiring checked; do not bridge protection.

J19-C and J12: compare the actual contact version

Product selection links — not a five-pin compatibility claim

Product	Current published contact information	What to request
J19-C-271 illuminated ring button	19mm; the listed variant is 1NO.	Exact terminal drawing and lamp voltage option. Do not assume COM/NO/NC.
J12-271 illuminated ring button	12mm; the listed variant is 1NO.	Confirm whether an ordered five-terminal changeover version exists before using this diagram.
J19 illuminated ring button	The page lists 1NO+1NC and 2NO+2NC versions.	Confirm whether contacts have a common terminal or separate pairs; contact count alone does not prove five pins.

Browse metal push buttons or request a verified terminal drawing for your exact order. Provide the model, operating action, voltage, load type/current and desired lamp behaviour. None of these links is a claim that every variant uses the five-terminal arrangement above.