Adjustability and variability are crucial when installing and maintaining electrical systems. As an electrician, having the right tools that can adapt to different situations is key. In this article, I’ve compiled a table of the most common symbols used to indicate adjustable and variable components in electrical schematics and wiring diagrams. Being able to quickly identify and understand these symbols allows electricians to properly interpret diagrams and ensure systems are wired correctly. Whether for lighting, motors or transformers, this symbol reference will support electricians in their work.
| Symbol | Description | Application notes |
 | Name: Adjustability, general symbol Source: IEC 60617-2019, IEC 60417-2020, IEEE Std 315-1993 | A1 |
 | Name: Adjustability, non-linear Source: IEC 60617-2019, IEC 60417-2020, IEEE Std 315-1993 | A1 |
 | Name: Preset (pre-set), general symbol. Alternative name: Adjustability, pre-set symbol Source: IEC 60617-2019, IEC 60417-2020, IEEE Std 315-1993 | A1, A2, A3, A4 |
 | Name: Pre-set adjustability. Remark: Pre-set adjustment permitted only at zero current. Source: IEC 60617-2019 | A1, A2, A3, A4 |
 | Name: Linear variability, general symbol. Alternative name: Linear inherent variability; Variability, general symbol Source: IEC 60617-2019, IEC 60417-2020, IEEE Std 315-1993 | A1, A2, A3 |
 | Name: Non-linear inherent variability Alternative name: Variability, non-linear Source: IEC 60617-2019, IEC 60417-2020, IEEE Std 315-1993 | A1, A2, A3 |
 | Name: Action in steps Source: IEC 60617-2019 | A5 |
 | Name: Adjustability step by step Remark: 5 steps shown. Source: IEC 60617-2019 | A1, A2, A5 |
 | Name: Continuous variability Source: IEC 60617-2019, IEC 60417-2020, IEEE Std 315-1993 | A1, A2 |
 | Name: Continuous variability, pre-set Source: IEC 60617-2019 or IEEE Std 315-1993 | A1, A2 |
 | Name: Automatic control Source: IEC 60617-2019, IEC 60417-2020, IEEE Std 315-1993 | A1, A2, A6 |
 | Name: Amplifier with automatic gain control Remark: Amplifier with automatic gain control shown. Source: IEC 60617-2019 or IEEE Std 315-1993 | A1, A2, A6 |
 | Name: Variability Source: IEC 60417-2020 | A7 |
 | Name: Stepwise variability Source: IEC 60417-2020 | – |
Application Notes
A1:
- “Variability” pertains to a quantity associated with a device represented by the symbol, the value of which is dependent on factors internal to the device.
- “Adjustability” pertains to a quantity associated with a device represented by the symbol, the value of which may be set or controlled by external means.
A2: The symbols for adjustabillity, variability and automatic control should be drawn across the main symbol at about 45° to the centre line of the latter symbol.
A3: Information on the controlling quantity, for example voltage or temperature, may be shown adjacent to the symbol.
A4: Information on the conditions under which adjustibility is permitted may be shown adjacent to the symbol.
A5: A figure indicating the number of steps may be added.
A6: The controlled quantity may be indicated adjacent to the symbol.
A7: To identify the control device by means of which a quantity is controlled. The controlled quantity increases with the figure width.
Last Updated on: October 27, 2023
