Switch (DPST — 4-pin Rocker) Symbol
Definition: The Switch (DPST — 4-pin Rocker) symbol represents a Double-Pole Single-Throw switch that simultaneously opens or closes two independent circuit poles with a single actuator, featuring four terminals (Pole 1 In, Pole 1 Out, Pole 2 In, Pole 2 Out), commonly implemented as a rocker switch, and standardised under IEC 60617-07 and ANSI Y32.2 / IEEE 315 as a double-pole single-throw switching device.
Also known as: DPST switch, double-pole single-throw, 4-pin rocker switch, double-pole on/off switch, two-pole switch.
What the Switch (DPST — 4-pin Rocker) symbol means
The DPST Switch symbol represents a switching device that simultaneously controls two separate circuit conductors with a single mechanical action. When the switch is open, both poles are disconnected; when closed, both poles connect simultaneously. This simultaneous switching of two conductors is essential when safety or circuit integrity requires that both the live and neutral (or both phases) are interrupted or connected together.
In wiring diagrams, the DPST symbol signals that a single physical switch or relay contact set controls two independent paths. This is the standard approach for appliance power switches that must disconnect both live and neutral (required in IEC countries for double-insulated appliances), and for switching two-phase or DC circuits where both conductors must be interrupted simultaneously to prevent shock or arc hazards.
How to identify the Switch (DPST — 4-pin Rocker) symbol
The DPST Switch symbol is drawn as two single-pole switch symbols (pivot arc and contact stub) side by side, sharing a common actuator line or mechanically linked indicator (a dashed line between the two switch bodies shows mechanical coupling). The four terminals are labelled: Pole 1 In and Pole 2 In on the left, Pole 1 Out and Pole 2 Out on the right. In rocker-switch representations, the block is sometimes shown as a single rectangle with four corner terminals.
Function in a circuit
A DPST switch simultaneously connects or disconnects two independent circuit poles using a single toggle or rocker actuator. Neither pole has any electrical connection to the other — they are completely isolated, simply sharing the mechanical actuator. This allows a single switch action to open or close a live/neutral pair (for AC isolation), two independent DC circuits, or two phases of a multi-phase supply simultaneously.
Standards: IEC vs ANSI
| IEC 60617 | IEC 60617-07 defines the DPST switch as a two-pole single-position make-break switch; the symbol shows two mechanically linked single-pole switch symbols with a dashed line indicating common actuation. IEC 60335 (household appliance safety) requires DPST switching for certain appliance power disconnects to interrupt both poles simultaneously. |
|---|---|
| ANSI/IEEE 315 | ANSI Y32.2 / IEEE 315 defines the DPST switch symbol as two SPST switches with a dashed mechanical link line between them. The double-pole arrangement is explicitly shown by the two parallel switch arcs and the link. Designator: SW or S. |
| Key difference | IEC and ANSI use the same DPST symbol convention — two mechanically linked SPST switch arcs with a dashed coupling line. The symbols are essentially identical in both standards. IEC practice more commonly requires DPST switching in appliance wiring for full isolation of both poles; ANSI/NEC practice sometimes permits single-pole switching for lighting but requires DPST for certain appliance and motor circuits. |
Terminals / pins
| Pin | Name |
|---|---|
| in1 | Pole 1 In |
| in2 | Pole 2 In |
| out1 | Pole 1 Out |
| out2 | Pole 2 Out |
Typical values
Typical ratings: 10 A at 250 V AC (IEC), 15 A at 125/250 V AC (NEMA/UL), 20 A at 250 V AC (heavy-duty). Poles: 2. Throws: 1. Terminals: 4 (2 input + 2 output). Actuator: rocker, toggle, slide, or push-button. Contact form: NO (normally open) in standard version; NC versions available.
Where the Switch (DPST — 4-pin Rocker) symbol is used
- Appliance power switches in washing machines, dishwashers, and ovens requiring simultaneous live+neutral disconnection
- 240 V AC single-phase equipment (water heaters, dryers, room air conditioners) switching both L1 and L2 phases
- Marine and RV electrical panels requiring full disconnection of both positive and negative DC conductors
- Laboratory power supplies where both output terminals must be disconnected from the input simultaneously
- Audio equipment power switches disconnecting both balanced +/− supply rails simultaneously
- Industrial control panel emergency-off buttons acting on two independent control circuits at once
- Battery charger output switches isolating both positive and negative terminals of a charging circuit
Example
In a 240 V electric water heater wiring diagram, a DPST Rocker Switch symbol appears with Pole 1 In connected to the black L1 conductor and Pole 2 In connected to the red L2 conductor. Pole 1 Out and Pole 2 Out feed the water heater element terminals. A single switch action simultaneously connects or disconnects both phases, ensuring the full 240 V is controlled by one switch without requiring two separate single-pole switches.
Key facts
- A DPST (Double-Pole Single-Throw) switch simultaneously opens or closes two independent circuit poles with a single mechanical actuator; it has four terminals: Pole 1 In, Pole 1 Out, Pole 2 In, and Pole 2 Out.
- The DPST switch symbol shows two mechanically linked SPST switch arcs with a dashed coupling line between them, per IEC 60617-07 and ANSI Y32.2 / IEEE 315.
- Neither pole of a DPST switch has any electrical connection to the other — the two poles are completely isolated circuits sharing only the mechanical actuator.
- DPST switches are required by IEC 60335 (household appliance safety) when a switch must provide full disconnection (both live and neutral poles) from a single switching action.
- Common ratings: 10 A / 250 V AC (IEC) and 15 A / 125 V or 250 V AC (NEMA/UL); rocker switch form factor is the most common implementation for panel-mounted DPST switches.
- DPST must not be confused with DPDT (double-pole double-throw): DPST has one throw position (make/break only), while DPDT has two throw positions (the movable contacts can connect to one of two fixed contacts per pole).
- In DC circuits, DPST switches are used to simultaneously disconnect both positive and negative conductors — essential in marine, automotive, and battery systems to prevent ground-fault currents and corrosion.
Diagrams that use this symbol
- selector switch 3 position wiring diagram
- 6 pin rocker switch wiring diagram
- double pole switch wiring diagram
- 6 pin dpdt switch wiring diagram
- dip switch diagram
- 3 pole switch wiring
- double pole switch diagram
Frequently asked questions
What does the DPST switch symbol mean in a circuit diagram?
The DPST (Double-Pole Single-Throw) switch symbol represents a switch that simultaneously opens or closes two independent circuit conductors with a single actuator. It has four terminals: Pole 1 In, Pole 1 Out, Pole 2 In, and Pole 2 Out. It is used where both poles of a supply must be switched simultaneously, such as 240 V appliance power switches or DC circuits requiring full isolation.
What does the DPST switch symbol look like?
The DPST switch symbol is drawn as two SPST (single-pole single-throw) switch arcs placed in parallel, with a dashed line mechanically linking their actuators to show that both poles switch simultaneously. The four terminals appear as two inputs on the left (Pole 1 In, Pole 2 In) and two outputs on the right (Pole 1 Out, Pole 2 Out). In panel diagrams, it may be shown as a rectangle with four terminals labelled accordingly.
What is the difference between DPST and DPDT?
A DPST (Double-Pole Single-Throw) switch has two poles and one throw — it can only make or break the circuit (on or off). A DPDT (Double-Pole Double-Throw) switch has two poles and two throw positions — each pole can connect to one of two different circuits, enabling both on/off and changeover switching. A DPST switch has 4 terminals; a DPDT switch has 6 terminals.
What is the difference between DPST and two SPST switches?
Electrically they are equivalent — both switch two independent circuits. The difference is the actuator: a DPST switch uses a single mechanical actuator (rocker, toggle) to switch both poles simultaneously, ensuring they always switch together. Two separate SPST switches would require two separate switch actions, potentially leaving one pole switched and the other not — a hazard for circuits requiring simultaneous interruption.
What standard defines the DPST switch symbol?
The DPST switch symbol is defined in IEC 60617-07 (switching devices) and ANSI Y32.2 / IEEE 315 (graphic symbols for electrical and electronics diagrams). Both standards show two mechanically linked SPST switch arcs with a dashed mechanical coupling line. IEC 60335 specifies when DPST switching is required in household appliances.
Where is a DPST switch used?
DPST switches are used wherever both poles of a supply must be interrupted simultaneously: 240 V AC appliances (dryers, water heaters, ovens), 230 V AC single-phase equipment in IEC countries requiring both live and neutral switching, DC battery systems requiring simultaneous positive and negative disconnection, laboratory power supplies, and audio/industrial equipment power switches.
What are the terminal names on the DPST switch symbol?
The DPST switch symbol has four terminals: Pole 1 In (input of the first pole), Pole 2 In (input of the second pole), Pole 1 Out (output of the first pole), and Pole 2 Out (output of the second pole). The two poles are electrically isolated from each other and connected only through the shared mechanical actuator.
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