Rotary Switch Symbol
Definition: The Rotary Switch symbol represents a multi-position selector in which a rotating wiper connects one Common terminal to one of several selectable contacts (here Pos 1 through Pos 4, making a 1-pole 4-throw or 1P4T switch), drawn per IEC 60617 multi-position switch convention as a central contact with a pivoting wiper arm sweeping an arc of contact dots.
Also known as: rotary switch, selector switch, multi-position switch, 1P4T switch, band switch, wafer switch, rotary selector.
What the Rotary Switch symbol means
The rotary switch symbol denotes the general solution to 'choose exactly one of N': a shaft-driven wiper that dials the Common terminal across a ring of stationary contacts, guaranteeing mechanically that only one selection is active at a time. Where a toggle offers two choices and a pushbutton one, the rotary scales to 12 or more positions per pole, which made it the canonical range selector on multimeters, band switch on radios, speed selector on fans, program selector on appliances and pickup selector on instruments.
The notation nPmT reads 'n poles, m throws': the specified symbol is 1P4T — one wiper, four destinations. Multi-pole rotaries stack additional wafers on the same shaft (drawn as additional wiper symbols joined by the dashed mechanical-link line), switching several circuits in lockstep — a 4P3T, for instance, moves four circuits together through three positions. Many rotary switches are configurable via an adjustable stop washer to limit rotation to fewer positions than the wafer provides.
How to identify the Rotary Switch symbol
The symbol shows a central terminal (Common) with a straight wiper arm pivoting from it, and an arc of small contact dots or stubs — one per position, here labelled Pos 1 to Pos 4 — arranged along the wiper's sweep. The wiper is drawn resting on one contact to show the current selection. Multi-pole versions repeat the wiper-and-arc motif with a dashed gang line linking the wipers.
ANSI Y32.2 / IEEE 315 uses essentially the same wiper-over-arc form; industrial IEC control drawings for panel selector switches (2- and 3-position cam switches) instead use contact-array notation with position tables, which is why a 12-position wafer switch and a 3-position panel selector can look different on paper while being the same idea. Don't confuse the rotary switch with the rotary encoder — the encoder is drawn as a block with quadrature outputs A/B and spins endlessly, while the switch's wiper arc has definite ends and discrete detents.
Function in a circuit
Electrically, each position is a simple closed contact between Common and the selected throw; every unselected throw is open. Rotating the shaft advances the wiper one detent at a time — typically 30° or 45° indexing — so the circuit steps cleanly from Pos 1 to Pos 2 to Pos 3 to Pos 4. A critical specification is what happens between detents: non-shorting (break-before-make) wipers disconnect from one contact before touching the next, essential when the positions carry different sources that must never bridge; shorting (make-before-break) wipers touch the next contact before leaving the last, keeping the circuit unbroken — preferred in audio attenuators to avoid pops and in meter range switches to avoid open-circuit transients.
In use, the rotary either routes a signal (selecting one of four inputs into an amplifier), reconfigures a network (selecting taps on a resistor chain, as in a stepped attenuator), or encodes a setting (each position wiring a different control combination). Its mechanical exclusivity — one and only one contact selected — is a correctness guarantee that software or relay logic would otherwise have to enforce.
Standards: IEC vs ANSI
| IEC 60617 | IEC 60617 provides multi-position switch symbols built from a wiper contact over an arc of positions, with the dashed coupling line for ganged poles; IEC 61058-1 covers appliance switch requirements and IEC 60947-5-1 covers control-circuit selector switches (panel cam types). |
|---|---|
| ANSI/IEEE 315 | ANSI Y32.2 / IEEE 315 defines the equivalent rotary/selector form (wiper and contact arc); military-era MIL-DTL-3786 governs rotary switch component quality for North American aerospace/defence use. |
| Key difference | Schematic wiper-and-arc forms are effectively identical. The divergence is in industrial-control documentation: IEC panel-selector practice frequently uses contact-block symbols with an X/O position-truth table beneath (showing which contacts close in which handle position), while North American JIC ladder drawings draw selector-switch contacts with position arrows. For electronics-style wafer rotaries, both communities draw the same symbol. |
Terminals / pins
| Pin | Name |
|---|---|
| common | Common |
| p1 | Pos 1 |
| p2 | Pos 2 |
| p3 | Pos 3 |
| p4 | Pos 4 |
Typical values
Common electronics rotary (wafer) switches: 1–6 poles, 2–12 positions per pole, 30° indexing (12-position base wafer) with adjustable stops; ratings around 0.3–0.5 A at 125 V AC or 100–200 mA DC switching, 1–2.5 A carry; contact resistance ≤20–50 mΩ; life 10,000–25,000 rotations. Panel cam selectors for control circuits: 2–3 positions typically, 10 A at 600 V AC (AC-15 duty ratings per IEC 60947-5-1). Guitar-style lever/rotary selectors: 3–5 positions. Specify shorting or non-shorting explicitly — both are standard catalogue options.
Where the Rotary Switch symbol is used
- Multimeter range and function selectors stepping one measuring circuit across many ranges
- Radio band switches and vintage TV/instrument selectors routing RF sections (the classic 'wafer switch' role)
- Stepped attenuators and input selectors in audio preamplifiers (often shorting-type to avoid pops)
- Fan, heater and appliance speed/program selectors choosing motor taps or heating elements
- Industrial panel selector switches (hand/off/auto, local/remote) in motor-control circuits
- Test equipment and calibration fixtures selecting one of several references, loads or DUT channels
Example
In a four-input audio selector, the preamplifier input connects to the rotary switch's Common terminal while the tuner, CD, aux and phono sources land on Pos 1, Pos 2, Pos 3 and Pos 4 respectively; a shorting (make-before-break) 1P4T wafer is chosen so the wiper bridges adjacent contacts for a few milliseconds during rotation, keeping the amplifier input from floating and thumping — with a stereo version simply stacking a second ganged pole on the same shaft for the right channel.
Key facts
- Notation nPmT gives poles and throws: the drawn symbol is 1P4T — one Common wiper selecting among four positions (Pos 1–Pos 4).
- Exactly one throw is connected to Common at any time; all others are open — mechanical guarantee of exclusive selection.
- Shorting (make-before-break) wipers keep the circuit continuous between positions; non-shorting (break-before-make) never bridge adjacent contacts — choosing wrongly can short two sources or pop an amplifier.
- Typical indexing is 30° (12 positions max per wafer) or 45° (8 positions), usually with an adjustable stop to limit the position count.
- Multi-pole rotaries gang extra wafers on one shaft, drawn as repeated wipers joined by the dashed mechanical-link line.
- Electronics wafer switches are signal-level parts (≈0.3–0.5 A); panel cam selectors are the industrial-power siblings rated 10 A+ per IEC 60947-5-1.
- A rotary switch has fixed end-stops and detents; a rotary encoder spins continuously and outputs quadrature pulses — different component, different symbol.
- The multimeter dial is the most-handled rotary switch in electronics — one reason meter accuracy specs include switch contact resistance.
Frequently asked questions
What does 1P4T (or 2P6T) mean on a rotary switch?
The nPmT code states poles and throws: 1P4T is one pole (a single Common wiper) with four throws (four selectable positions), matching this symbol's Common plus Pos 1–4. A 2P6T has two ganged wipers each selecting among six contacts, switching two circuits in lockstep. Poles multiply the circuits switched simultaneously; throws set how many positions each circuit can be routed to.
What is the difference between shorting and non-shorting rotary switches?
It's the behaviour mid-rotation. A shorting (make-before-break) wiper contacts the next position before releasing the current one, so the Common is never open — but adjacent throws are momentarily bridged. A non-shorting (break-before-make) wiper opens first, so throws are never bridged — but the Common floats briefly. Use shorting for audio selectors and meter ranges (no pops, no open-circuit spikes); use non-shorting whenever positions connect to different sources or voltages that must never touch.
What is the difference between a rotary switch and a rotary encoder?
A rotary switch makes real electrical connections: its wiper physically routes Common to one of a fixed set of contacts, has end stops, and holds its selection with no power. A rotary encoder is an input device that spins endlessly and outputs pulse trains (quadrature A/B or Gray code) that a microcontroller counts — it selects nothing by itself. Front panels have largely moved to encoders plus software, but switches still rule where the selection must be hard-wired, unambiguous and power-independent, like a multimeter dial.
Can a rotary switch handle mains or motor loads?
Electronics-style wafer rotaries cannot — they're signal switches rated a few hundred milliamps. For mains and motor duty use industrial cam-type selector switches rated to IEC 60947-5-1 (e.g. 10 A AC-15) or appliance-rated rotary switches to IEC/UL 61058-1, which have proper arc-quenching contact blocks. Fan and heater speed selectors in appliances are exactly this heavier class. Match the utilisation category (resistive vs inductive) and never rely on a signal wafer to break an inductive mains load.
How do you wire a rotary switch as a multi-position selector?
Bring the shared line — the amplifier input, the meter movement, the supply feed — to the Common terminal, and wire each selectable source or configuration to Pos 1 through Pos 4. Rotating the knob then routes Common to exactly one of them. For multiple simultaneous circuits (stereo pairs, voltage+current paths), use a multi-pole version and wire each pole identically; the dashed-line ganging keeps every pole on the same position number automatically.
Related symbols
- Ignition Switch (Multi-Position) symbol
- Rotary Encoder symbol
- Selector Switch 2-Position symbol
- Selector Switch 3-Position symbol
- Slide Switch symbol
- Switch (SPST) symbol
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