Doorbell Button Symbol
Definition: The Doorbell Button symbol represents a normally-open (NO) momentary pushbutton switch in residential wiring diagrams that, when pressed, briefly closes the low-voltage circuit between the doorbell transformer and the indoor chime unit to produce an audible alert, depicted as a normally-open pushbutton symbol with terminals A and B, referenced in IEC 60617 and ANSI Y32.2 / IEEE 315.
Also known as: door push button, doorbell push, chime button, entry button, doorbell actuator, bell push.
What the Doorbell Button symbol means
The Doorbell Button symbol marks the location of the outdoor or entry-point pushbutton in a doorbell wiring diagram—typically mounted on the door frame or door surround adjacent to the entry door. The symbol indicates a spring-return, normally-open momentary contact switch that is actuated by a visitor pressing the button, completing the low-voltage circuit momentarily.
In doorbell wiring diagrams the Doorbell Button symbol has two terminals: A connects to one conductor of the low-voltage loop and B connects to the return conductor. When no one is pressing the button the contacts are open (A and B disconnected); pressing the button closes the contacts, allowing current to flow through the chime unit and produce the alert tone.
How to identify the Doorbell Button symbol
The Doorbell Button glyph is drawn as a normally-open (NO) pushbutton switch symbol—two short contact lines (fixed and moving) with a vertical actuating arrow indicating downward press action—on a pair of conductor lines connecting terminals A and B. The symbol may include an enclosing rectangle or circle representing the button housing (typically a square or round flush-mount plate). It is distinguished from a maintained switch (which stays latched) by the spring-return actuating arrow, and from a toggle switch by the momentary operation convention.
Function in a circuit
The doorbell button functions as a momentary normally-open (NO) switch in series in the low-voltage doorbell circuit. In its rest state (not pressed) the circuit between the transformer secondary and the chime is open, so no current flows and the chime remains silent. When a visitor presses the button the switch contacts close, completing the circuit and driving current through the chime solenoid or electronic tone circuit. Releasing the button returns the contacts to the open state, ending the tone.
Standards: IEC vs ANSI
| IEC 60617 | IEC 60617 represents the doorbell button as a normally-open pushbutton (make contact) symbol, a standard element in the switching-device symbol set. IEC 60947-5-1 governs pushbutton performance as control circuit devices. Low-voltage doorbell circuit wiring is governed by SELV requirements per IEC 61140. |
|---|---|
| ANSI/IEEE 315 | ANSI Y32.2 / IEEE 315 defines the normally-open pushbutton switch symbol. NEC (NFPA 70) Article 725 Class 2 wiring rules apply to the low-voltage doorbell circuit wiring, allowing 18–22 AWG conductors. |
| Key difference | IEC and ANSI symbols for the doorbell pushbutton are identical normally-open (NO) momentary pushbutton switch glyphs. The main practical difference is in wiring regulations: NEC Article 725 (North America) vs. IEC SELV requirements (international). The symbol itself is the same. |
Terminals / pins
| Pin | Name |
|---|---|
| a | A |
| b | B |
Typical values
Contact voltage rating: 24 V DC or 24 V AC (SELV class). Contact current rating: typically 0.5 A to 2 A. Actuation force: 1–5 N. Weather resistance: IP44 to IP65 for outdoor mounting. Wire termination: screw terminals for 18–22 AWG conductors. LED illumination: some versions include a 5–16 V LED indicator visible at night.
Where the Doorbell Button symbol is used
- Front-door entry button mounted on the door frame to alert occupants of visitor arrival
- Rear or side-door entry buttons in larger residences with multiple access points wired to a multi-tone chime
- Apartment intercom entry panel as the call button per apartment or per dwelling unit
- Small commercial offices and retail shops as a customer-entry notification button
- Gate and perimeter-wall entry call points connected to an indoor chime or intercom
- Assisted-living facilities as a patient call button wired to a nurse call or chime system
Example
In a residential doorbell wiring diagram, the Doorbell Button symbol is placed at the front door frame; terminal A connects via 18 AWG low-voltage wire to the 'front' terminal of the indoor chime unit, and terminal B connects back to the common terminal of the chime (which connects to the 16 V AC transformer secondary). When the button is pressed, the circuit is completed: transformer → chime solenoid → doorbell button contacts → transformer return path, sounding the chime.
Key facts
- The Doorbell Button symbol represents a normally-open (NO) momentary pushbutton switch with terminals A and B; in its rest state the contacts are open (circuit broken), and pressing the button momentarily closes the contacts to energise the chime.
- Doorbell button circuits operate at SELV low voltage—typically 8–24 V AC—governed by NEC Article 725 (Class 2 wiring) in North America and IEC 61140 SELV requirements internationally, allowing smaller wire gauges (18–22 AWG) than mains wiring.
- Outdoor doorbell buttons must be rated for weather protection; typical IP ratings are IP44 (splash-proof) to IP65 (jet-proof) for exposed door-frame mounting. Stainless steel and brass housings resist corrosion.
- Many modern doorbell buttons include an integrated LED indicator (typically blue or white) powered by the same low-voltage circuit, making the button visible at night; illuminated buttons draw a small continuous current (5–20 mA) even when not pressed.
- Smart video doorbell cameras (Ring, Nest, Eufy) are designed as a replacement for the conventional doorbell button while using the same two-wire low-voltage doorbell wiring (A and B terminals) already installed at the door frame.
- Multi-button doorbell systems (front and back door) use a three-conductor cable to the chime: one common conductor from the transformer, one conductor per button location; the chime produces different tones for each button.
- The doorbell button contacts must be rated for the full transformer current—not just the momentary current at the chime—because inrush current to the chime solenoid at the moment of contact closure can be 5–10 times the steady-state current.
Diagrams that use this symbol
- doorbell wiring diagram
- door bell wiring diagram
- buzzer circuit diagram
- doorbell transformer wiring diagram
- doorbell chime wiring diagram
- 4 wire doorbell wiring diagram
- doorbell circuit diagram
- single doorbell wiring diagram
Frequently asked questions
What does the doorbell button symbol mean in a wiring diagram?
The Doorbell Button symbol represents a normally-open (NO) momentary pushbutton switch located at the entry door; when pressed it briefly closes the low-voltage circuit between the doorbell transformer and the indoor chime unit, producing an audible alert. When not pressed, the circuit is open and no current flows.
What does the doorbell button symbol look like?
The Doorbell Button symbol is drawn as a normally-open (NO) pushbutton switch—two short contact lines with a vertical actuating press-arrow—on a pair of circuit conductors representing terminals A and B. An enclosing circle or rectangle is sometimes added to represent the physical button housing on the door frame.
Is the doorbell button normally open or normally closed?
The doorbell button is normally open (NO): in its rest state (not pressed) the contacts are open and no current flows. Pressing the button momentarily closes the contacts, completing the circuit and energising the chime. Releasing the button returns the contacts to the open position via an internal spring.
What are the A and B terminals on the doorbell button symbol?
Terminal A connects to one conductor of the low-voltage doorbell circuit loop—typically the conductor running from the front-door terminal of the indoor chime unit. Terminal B connects to the return conductor back to the chime common terminal, which is connected to the transformer secondary. When the button is pressed, A and B are shorted, completing the chime circuit.
What voltage does a doorbell button operate on?
Doorbell buttons operate at low voltage—typically 8 V, 16 V, or 24 V AC—provided by a step-down doorbell transformer connected to the household mains. This voltage is classified as SELV (Safety Extra-Low Voltage) and is governed by NEC Article 725 Class 2 wiring rules in North America, allowing smaller wire gauges and simplified installation.
Can I replace my doorbell button with a smart doorbell camera?
Yes. Smart video doorbells (Ring, Nest, Eufy) are designed to replace a conventional doorbell button using the same two-wire low-voltage wiring (A and B terminals) already installed. The smart doorbell draws its operating power from the transformer through the same two wires, while adding video, audio, and Wi-Fi connectivity. Ensure the transformer is rated at 16–24 V AC with at least 30–40 VA capacity.
What IP rating should a doorbell button have for outdoor use?
For outdoor door-frame mounting, a doorbell button should be rated at a minimum of IP44 (splash-proof from any direction) for sheltered locations. For exposed locations without a porch cover, IP54 to IP65 (dust-tight and jet-proof) is recommended. Coastal or very humid environments benefit from stainless steel or UV-resistant plastic housings.
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