Apartment wiring devices · Practical guides
Classifying switches by gang count, switching arrangement, sensors and timers
Switch symbols vary more than outlet symbols, and a single device can control several circuits. Keep device counts separate from circuit counts to avoid doubling or halving quantities.
Decide what counts as one device
Switch quantity schedules usually count one device as one item. A 2-gang switch is one device containing two switches on a plate, so its quantity is 1 and its specification is ‘2-gang’. A wiring diagram or circuit schedule may instead show two circuits. Align the basis of the quantity schedule with the BOQ.
Numbers beside a switch symbol may indicate the gang count; marks such as 3 or 4 may indicate a 3-way or 4-way switching arrangement; lowercase letters often identify the lighting circuit controlled. Check each meaning in the legend before counting.
How to separate switch types
- Number of sockets: 1-gang, 2-gang, 3-gang, 4-gang or more
- Switching arrangement: 1-way (single-pole), 3-way and 4-way. Three-way and four-way switches control lights from two or more locations, such as long corridors or stairs.
- Function: Occupancy sensors, timers, dimmers, indicator-light switches and master lights-off switches
- Installation method/environment: Flush-/surface-mounted; weatherproof (outdoor/balcony)
- Combined devices: A combined switch-and-outlet plate is a separate item.
Three-way switches usually occur in pairs. If you have counted only one, check whether its partner appears on another sheet, such as the stairwell plan, or has been omitted.
Common switch-counting errors
- Counting circuit labels as devices: A 2-gang switch labelled with circuits ‘a’ and ‘b’ is still one device.
- Confusion with lighting-fixture symbols: Some designs use luminaires with integrated sensors and no wall switch. If a room has no switch, check its lighting-fixture specifications.
- Master lights-off and entrance switches: Master lights-off switches and standby-power isolation switches at the entrance are different items from ordinary switches.
- Weatherproof bathroom/balcony devices: Keep devices separate when the legend marks one as weatherproof, even if their symbols otherwise look alike.
Cross-check switches against lighting circuits
After counting switches, check each room against ‘lighting circuit count ≥ switch circuit count’ to catch major omissions. A luminaire circuit label missing from every switch may indicate a missing switch or one on another sheet. Voltix’s Published example labels seven 1-gang switches S01–S07 on a dwelling-unit plan so you can follow this comparison.
Sources and scope
This article provides general guidance on reviewing apartment wiring-device quantities. For project decisions, the relevant drawing legend, revision information, specifications and contract scope take precedence. See our Editorial review and correction policy.
Scope and limitations of the published drawing and Excel examples · Report an error or ask about supported scope