Single-pole switch
An ordinary light switch that controls a light from one place. Plans mark it with the letter S.
Easily confused with
How to read it
NECA 100 lists the single pole switch first among its switch symbols, before the double pole, three-way and four-way switches. The Army's print-reading manual gives the same order, marking the others with S2 and S3.
Also searched as: light switch symbol, switch S.
This explains what a symbol represents on a drawing. Conventions vary between firms and standards, and a drawing's own legend takes precedence.
Look-alikes
An S with a small 3 is a three-way switch.
Read next
More blueprint symbols
The same shape elsewhere
Browse symbols drawn with letters and numbers.
Sources
- Symbols for Electrical Construction Drawings, NECA 100-2013 (ANSI), National Electrical Contractors Association (Internet Archive copy), sec. 4.0, symbol 4.001
- Construction Print Reading in the Field, TM 5-704 / AFM 85-27, Departments of the Army and the Air Force, fig. 3-32; app. B, fig. B-9
- Reading Architects' Blueprints, William S. Lowndes, 1922, International Textbook Company, Scranton (Internet Archive), §6, art. 44
Researched, edited and approved by Rory Hansen before publishing. Last reviewed September 30, 2026. How we research
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