Quartz 4

SSO Occupancy Sensor

9 min read

Occupancy Sensor - Quick Reference SSO

Device Type: Binary Input - Motion/Presence Detection
Signal: Dry contact (relay output) or 0-10VDC
Power: 24VAC/VDC or 120VAC (depending on model)
Version: 1.0 | Date: Dec 2025

DEVICE OVERVIEW

Common Models:

  • Leviton OSC/ODC, Lutron LOS, Wattstopper DT/CI, Honeywell HRME, Sensor Switch CMD

Used For:
Lighting control (auto on/off), HVAC setback (unoccupied mode), demand control ventilation, security/access, energy savings

Technologies:

  • PIR (Passive Infrared): Detects body heat/motion - best for large open areas
  • Ultrasonic: Detects movement via sound waves - best for restrooms, behind obstructions
  • Dual-Tech: PIR + Ultrasonic combined - reduces false triggers
  • Daylight Harvesting: Integrated light sensor for dimming control

Specifications:

  • Detection Range:
    • Ceiling mount PIR: 360° coverage, 20-30 ft radius
    • Wall mount PIR: 180° coverage, 15-20 ft range
    • Ultrasonic: 10-15 ft typical
  • Output:
    • Dry contact relay (NO or NC)
    • 0-10VDC analog (for dimming or occupancy level)
  • Power: 24VAC/VDC (low-voltage) or 120VAC (line-voltage)
  • Time Delay: Adjustable 30 sec - 30 min typical
  • Sensitivity: Adjustable (low/medium/high)

Environment: Indoor, 32-104°F, 0-95% RH non-condensing

SAFETY - PPE REQUIRED

  • ☑ Safety glasses (ANSI Z87.1)
  • ☑ Work gloves
  • ☑ Insulated gloves if 120VAC model
  • ☑ Ladder safety equipment (ceiling mount)

HAZARDS

  • ⚠️ LADDER WORK - Most common hazard (ceiling mounting)
  • ⚠️ LINE VOLTAGE - 120VAC models have lethal voltage
  • ⚠️ FALLING OBJECTS - Sensor or tools can fall during ceiling install

LOCKOUT/TAGOUT

  • Required for 120VAC models - Lock out lighting circuit
  • NOT required for 24VAC/VDC low-voltage models
  • Verify voltage before touching wires

INSTALLATION CHECKLIST

TOOLS NEEDED

  • Drill + bits
  • Wire strippers
  • Screwdrivers
  • Multimeter
  • Ladder (appropriate height)
  • Voltage tester
  • Label maker
  • Small flathead (for DIP switch adjustment)

MATERIALS

  • Occupancy sensor (correct type for application)
  • Wire (18AWG for low-voltage, 14AWG for line-voltage)
  • Wire nuts
  • Ceiling/wall mounting hardware
  • Labels

PRE-INSTALL

  • Select correct sensor type (PIR, ultrasonic, dual-tech)
  • Verify coverage area adequate for space
  • Confirm mounting height appropriate (8-12 ft typical for ceiling)
  • Check power available (24V or 120V)
  • Review wiring diagram for model

INSTALL STEPS - CEILING MOUNT (Most Common)

STEP 1: Locate Mounting Position

  1. Coverage considerations:

    • Center of room preferred (360° PIR coverage)
    • Avoid corners (dead zones behind sensor)
    • Avoid direct line of sight to HVAC diffusers (air movement triggers ultrasonic)
    • Avoid windows with direct sunlight (can trigger PIR)
    • Height: 8-12 ft typical (follow manufacturer spec)

  2. Mounting location:

    • Ceiling: Use electrical box or sensor mounting bracket
    • Wall: 6-8 ft height typical, aimed at expected occupant location

STEP 2: Install Sensor

LOW-VOLTAGE (24VAC/VDC) - MOST COMMON FOR BAS:

  1. Lock out power if integrating with lighting circuit
  2. Mount sensor to ceiling:
    • Attach to electrical box or bracket
    • Route low-voltage control wire through ceiling to sensor
  3. Connect wiring:
    • Power (if required):
      • Red: +24VAC/VDC
      • Black: Common
    • Relay Output to Controller:
      • Relay NO: To controller binary input
      • Relay COM: To controller common
    • When occupied: Relay closes = BI TRUE
    • When vacant: Relay opens = BI FALSE
  4. Tighten terminals: 7-9 in-lbs

LINE-VOLTAGE (120VAC) - LIGHTING CONTROL:

  1. LOCK OUT lighting circuit breaker
  2. Verify 0V with voltage tester
  3. Mount sensor
  4. Connect wiring:
    • Black (hot) from breaker → Sensor line input
    • White (neutral) → Sensor neutral
    • Red (switched hot) → Sensor load output → Lighting
    • Green/bare (ground) → Sensor ground
  5. For BAS integration:
    • Use sensor’s low-voltage relay output (if available)
    • Connect relay to controller binary input

STEP 3: Configure Sensor Settings

DIP SWITCHES or ROTARY DIALS (varies by model):

  1. Time Delay:

    • Lighting: 5-15 min typical
    • HVAC: 15-30 min typical
    • Set longer for areas with intermittent occupancy

  2. Sensitivity:

    • High: Detects small movements (office, classroom)
    • Medium: Normal movements (conference room)
    • Low: Large movements only (warehouse)

  3. Mode:

    • Auto On/Auto Off: Turns on when occupied, off when vacant
    • Manual On/Auto Off: Must manually turn on, auto turns off
    • Vacancy Mode: Manual on, auto off (energy code compliant in some areas)

  4. Photocell (if equipped):

    • Enable: Prevents operation if daylight adequate
    • Disable: Operates regardless of light level

  5. Coverage Pattern (some models):

    • 360° for ceiling mount
    • Sector coverage for wall mount

STEP 4: Label Wiring

  • Example: “RM-201-OCC” (Room 201 Occupancy)
  • Label at both sensor and controller ends

STEP 5: Test and Adjust

  • See Proof Out Tests section

POST-INSTALL

  • Sensor mounted securely (ceiling or wall)
  • Coverage area verified
  • Wiring terminated tight
  • Settings configured (time delay, sensitivity, mode)
  • Labels applied
  • Work area cleaned
  • Photos taken

EXPECTED READINGS

INITIAL POWER-UP (Room Empty)

  • After time delay expires: Relay open = FALSE/0 (vacant)
  • Sensor LED: May blink when detecting motion (varies by model)

OCCUPIED (Person in Room)

  • Relay Output: Closed = TRUE/1 (occupied)
  • Controller Display: Shows “Occupied”
  • Sensor LED: May illuminate or blink (varies)

VACANT (Person Leaves Room)

  • During time delay: Relay stays closed (still occupied)
  • After time delay: Relay opens = FALSE/0 (vacant)
  • Example: 15-min delay means sensor shows vacant 15 min after last motion

PROOF OUT TESTS

TEST 1: Initial Detection Test

  • Do: Walk into sensor coverage area
  • Expect:
    • Sensor LED blinks or illuminates (if equipped)
    • Relay closes within 1-2 seconds
    • Controller shows “Occupied”
  • Pass If: Sensor detects occupancy immediately

TEST 2: Coverage Area Test

  • Do: Walk around room in grid pattern, all areas
  • Expect:
    • Sensor detects motion in all areas
    • No “dead zones” where motion not detected
  • Pass If: Full room coverage confirmed
  • If dead zones: Adjust sensor aim or add additional sensor

TEST 3: Time Delay Verification

  • Do:
    1. Occupy room (trigger sensor)
    2. Leave room and stand outside
    3. Time how long until sensor shows vacant
  • Expect: Sensor shows vacant after configured time delay
  • Pass If: Time delay matches setting (±10%)
  • Example: Set to 15 min, should trigger 14-16 min after last motion

TEST 4: Sensitivity Test

  • Do: Make small movements (typing, reading) in various locations
  • Expect:
    • High sensitivity: Detects small movements
    • Medium sensitivity: Detects normal movements
    • Low sensitivity: Detects only large movements
  • Pass If: Sensitivity appropriate for space use
  • Adjust if: False triggers (too sensitive) or misses occupancy (not sensitive enough)

TEST 5: False Trigger Test

  • Do: Room empty, observe sensor for 30 minutes
  • Expect: No false triggers from:
    • HVAC airflow
    • Sunlight movement
    • Reflections
    • Nearby motion outside room
  • Pass If: No false occupancy triggers
  • If false triggers: Adjust sensitivity, reposition sensor, or cover windows

TEST 6: Integration with BAS

  • Sensor appears in controller BI list
  • Occupied/vacant status displays correctly
  • Graphics show occupancy status
  • HVAC responds to occupancy (setback when vacant)
  • Lighting responds (if integrated)
  • No communication errors

TROUBLESHOOTING

SENSOR NEVER SHOWS OCCUPIED

  1. Check power: Verify 24VAC or 120VAC present
  2. Test sensor: Walk directly under sensor, wave arms
    • If LED blinks but no relay: Wiring issue
    • If no LED blink: Sensor failed or power issue
  3. Check wiring: Verify relay output connected to controller BI
  4. Test relay: Measure continuity across relay contacts when occupied
    • If no continuity: Sensor relay failed
  5. Check controller config: BI configured as NO contact?

SENSOR ALWAYS SHOWS OCCUPIED

  1. Check for false triggers:
    • HVAC airflow directly at sensor (ultrasonic)
    • Sunlight through windows (PIR)
    • Reflective surfaces (mirrors, shiny floors)
    • Motion outside room (open doorway)
  2. Reduce sensitivity: Adjust to medium or low
  3. Reposition sensor: Away from triggers
  4. Check wiring: Short circuit causing relay to stay closed?
  5. Check relay: Relay contacts stuck closed - replace sensor

SLOW TO DETECT OCCUPANCY

  1. PIR sensors require motion:
    • Person must move to be detected
    • Sitting still may not trigger sensor
    • Solution: Use ultrasonic or dual-tech
  2. Check sensitivity: May be set too low
    • Increase sensitivity setting
  3. Check dead zones: Person may be in coverage gap
    • Reposition sensor or add additional sensor

SENSOR DOESN’T STAY ON LONG ENOUGH

  1. Increase time delay:
    • Lighting: Try 10-15 min
    • HVAC: Try 20-30 min
  2. Check sensor type:
    • PIR requires movement to reset timer
    • Ultrasonic better for seated occupants
  3. Consider dual-tech: Maintains occupancy better

SENSOR STAYS ON TOO LONG

  1. Decrease time delay:
    • Set to minimum acceptable for application
  2. Check for false triggers:
    • May be constantly re-triggering from HVAC, sunlight, etc.

FALSE OCCUPANCY TRIGGERS

PIR False Triggers:

  • Sunlight movement through windows → Add blinds or reposition
  • Heat sources (space heaters, equipment) → Reposition sensor
  • Air movement from diffusers → Adjust sensitivity

Ultrasonic False Triggers:

  • HVAC air turbulence → Reposition or reduce sensitivity
  • Fans or moving equipment → Reduce sensitivity
  • Sound/vibration → Isolate sensor from vibration source

SENSOR MISSES OCCUPANCY (Not Detecting Present Person)

  1. Check coverage area: Person in dead zone?
  2. Increase sensitivity: May be set too low
  3. Check sensor type:
    • PIR only detects movement (not presence)
    • Person sitting still won’t trigger PIR
    • Solution: Use ultrasonic or dual-tech
  4. Check sensor aim: Wall-mount sensors must aim at occupied area
  5. Check obstructions: Furniture, partitions blocking view

ESCALATION - COMPLETE BEFORE CALLING

PRE-ESCALATION CHECKLIST

  • Verified power at sensor (24VAC or 120VAC)
  • Tested sensor by walking under it (LED response)
  • Measured relay output continuity (open vs closed)
  • Checked wiring connections tight
  • Verified coverage area (no dead zones)
  • Checked for false trigger sources (HVAC, sunlight)
  • Adjusted sensitivity and time delay settings
  • Documented sensor behavior over 30+ minutes
  • Taken photos of sensor location and settings

PROVIDE THIS INFO

  • Sensor: [Mfg / Model / Type: PIR/Ultrasonic/Dual / Location]
  • Power: 24VAC/VDC or 120VAC
  • Coverage Area: _____ ft² (room size)
  • Mounting Height: _____ ft
  • Sensor Behavior: Never occupied / Always occupied / Intermittent / Slow
  • LED Activity: Blinks / Doesn’t blink / Always on
  • Relay Status: Open / Closed / _____ ohms
  • Time Delay Setting: _____ minutes
  • Sensitivity Setting: High / Medium / Low
  • False Trigger Sources: HVAC / Sunlight / None identified
  • Symptoms: [Specific problem]
  • Steps Taken: [Troubleshooting completed]

CONTACTS

  • Field Specialist: [Phone]
  • Electrician: [Phone] (if 120VAC wiring issue)
  • Programmer: [Phone] (if control logic issue)
  • Dispatch: [Phone]

COMMON ISSUES & TIPS

✓ Sensor selection: PIR for large open areas, ultrasonic for restrooms/obstructed areas, dual-tech for best performance
✓ Mounting height: 8-12 ft typical - too high reduces sensitivity, too low reduces coverage
✓ Time delay: Longer for HVAC (20-30 min), shorter for lighting (5-15 min)
✓ PIR limitation: Only detects movement, not presence - person sitting still won’t maintain occupancy
✓ Ultrasonic advantage: Detects small movements (typing, breathing) - better for seated occupants
✓ False triggers: HVAC airflow (ultrasonic), sunlight (PIR), nearby motion (both)
✓ Dead zones: Directly below ceiling mount sensor, behind obstructions
✓ Energy codes: Some jurisdictions require vacancy mode (manual on) vs auto on
✓ Coverage overlap: Multiple sensors can share same space, extend time delay
✓ Dual-tech operation: BOTH technologies must trigger for occupancy (reduces false triggers)
✓ Daylight harvesting: Use photocell to prevent operation during daylight (additional energy savings)
✓ Integration: Use for HVAC setback, lighting control, security, demand control ventilation

Typical Applications & Time Delays

  • Private Offices: 15-20 min (intermittent occupancy)
  • Conference Rooms: 20-30 min (presentations = minimal movement)
  • Classrooms: 15-20 min (lecture = seated students)
  • Restrooms: 5-10 min (short-term occupancy)
  • Break Rooms: 10-15 min (variable use)
  • Warehouses: 30 min (large space, intermittent activity)
  • Corridors: 5-10 min (transient occupancy)

Document ID: SSO-OCCUPANCY-001
Revision: 1.0
Next Review: Dec 2026

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