Electrical symbols used in house wiring industry

Written by carlos mano | 13/05/2017
Electrical symbols used in house wiring industry
House wiring schematics are somewhat different from electronic device schematics. (tv and cupids image by ann triling from Fotolia.com)

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.

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