Electrical symbols used in house wiring industry

Updated February 21, 2017

Electronic circuit schematics do not dictate how the components are arranged -- it is up to the reader. House wiring diagrams are different. The components are precisely arranged on a blueprint which includes the names of the rooms.

Basic Components

Most home wiring symbols are circles . For receptacles (where things plug in), there will be two parallel lines in the circle. For a switch, there is an X in the circle, and smoke detectors have the letters SD in the circle. If there is a number beside the circle, it refers to the circuit breaker associated with the component.

Additional Information

If there is additional information about a component, it is indicated with a hexagonal box with a number in it. The number refers to the legend section of the blueprint which gives the additional information, such as the part number of the component and when a light is recessed or a fan has a three-way switch.


There are two conventions that describe whether a component is wall-mounted or ceiling mounted. Wall mounts have a line next to the circle with a short connecting line. Ceiling mounts have four short lines radiating from the circle. An F in the circle indicates a fan, a T represents a thermostat and no letter indicates a light.

Cite this Article A tool to create a citation to reference this article Cite this Article

About the Author