How to show smoke alarms on building diagrams

Written by keith allen
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How to show smoke alarms on building diagrams
A polygon is one way of representing smoke alarms in building diagrams. (Jupiterimages/ Images)

Smoke and fire alarms are common features in most buildings today. In fact, building codes in most areas typically require the devices. There are universal indicators for smoke and fire alarms used on blueprints and other building diagrams. The symbols not only indicate the placement of the alarm but the type of smoke or fire alarm, according to the National Fire Protection Association. Different organisations and industries have different ways of representing smoke alarms in building diagrams.

Skill level:
Moderately Easy


    National Fire Protection Association

  1. 1

    Draw the six-sided polygon indicating a smoke or fire alarm. The shape includes two parallel lines at the top and bottom connected on each end by a two-part angle with the point set away from the centre of the polygon. Make the polygon large enough to contain the two- or three-letter code for the type of detector.

  2. 2

    Add the code for the type of smoke detector. SI is an ionisation type of smoke detector, and SP is a photoelectric type. Other fire detector types include HF for heat detector fixed temperature and HR for heat detector rate of rise. FI is the proper abbreviation for flame detector infrared, while FV is for flame detector ultraviolet.

  3. 3

    Draw lines to connect the smoke alarm symbol to power sources and alarm stations, if present. Documents giving more details about each alarm often accompany the building diagrams.

    Electrical Blueprint Symbols

  1. 1

    Draw a circle on the blueprint. Size the circle appropriately based on the size of the smoke detector and the scale of the blueprint.

  2. 2

    Place the letter "S" or the letters "SD" in the circle. These are the abbreviations used commonly in blueprints and building diagrams.

  3. 3

    Add lines for the appropriate electrical service or to indicate wires leading to control panels. Note the specifications of the smoke detector in the notes of the blueprint or diagram.

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