Bosch Blue Line Intrusion Motion Detector Tested
False alarms from motion sensors are one of the most aggravating parts of intrusion detection.
Bosch says their sensors are better, even claiming their premium Blue Line PIR series give no false alarms.
In this test, we bought the Blue Line Pet Immune Gen2 sensor through the paces. Criteria tested includes:
- Angle of Detection
- Pet Immunity Function
- Detection Reliability
Sensor performance proved to match or better specsheet claims, with no false alarms or missed alarm events. While detection range is sufficient for most residential and small commercial spaces, the narrow detection zone at close ranges could be a problem and force mounting in difficult corner locations.
The pet-immunity feature worked well, and the option to turn it off helps the sensor in high-security applications.
Pricing for Bosch Blue Line sensors tend to be modestly more expensive than comparable sensors from other manufacturers.
Tested Model Details
Of the ~15 motion sensors Bosch produces, we chose a PIR-only, 'Pet Friendly' model named ISC-BPR2-WP12. The specs of this model claim a 40' X 40' (12m X12m) coverage area, and small animal detection immunity to 45 lbs (20 kg). Our unit cost ~$15. Given these specs, we chose this unit to test because it represents the most typical and applicable unit for both residential and commercial office locations.
Other models in the same series offer higher-end multi-tech PIR and microwave detectors that cost up to ~$100 each. Higher priced units cover up to 60' X 80' areas, and include anti-masking detection.
Bosch Blue Light sensors are named for the blue 'Alarm' status light on the front of the unit, instead of the red lights used on most other sensors. The light allows visual confirmation of sensor detection:
The other key factors of this model are a maximum 40'X40' range in a cone field pattern and a separate Pet Immunity sensor under the main sensor lens. The hardwired model is designed to permanently mount on walls, but adapter brackets can be purchased for ceiling or pivoting gimbal applications.
The sensor comes in two pieces:
Back Plate: The wall mounted bracket includes a wiring terminal block and small bubble-level vial to aid level mounting
Sensor Body: The main front piece includes the blue LED, the PIR sensors, and switches from turning the light and Pet Immunity functions on/off. The sensor body is sealed against bugs and slides until locking into place with the back plate.
Together, assembled pieces measure ~4" X 2.5" X 1.5" and can be mounted flush or in the corner of two walls.
Angle of View
Next to detection range, a motion sensor's angle of coverage is a key performance spec. The Bosch ISC-BPR2-WP12 claims a detection angle of 94° from center, leaving blind zones of ~44° on each side. The unit's spec sheet shows coverage angles:
The blindspots are significant enough to warrant careful placement in wide rooms to wall corners, otherwise the unit's angle of coverage potentially leaves large patches of undetectable area close to the sensor and may fall outside detection zones. The unit's angle of coverage is best when corner mounted in a room, but the physical construction or arrangement of the area may make locating the sensor and running cable to it difficult.
We checked the detection range by moving close to the sensor and found the deadspot matched the spec sheet's claims closely, generally within a degree:
The other key performance claim is detection distance, or range. The Bosch unit claims a 40' range, which our test shows to be a conservative maximum. We tested up to 45' with reliable detection. Movement under, near, intermediate to, and far from the sensor all triggered alarms in tests done both in daytime and nighttime, and with the alarm panel on main wall power and on battery backup.
Even at close to maximum detection range, the Bosch unit did not fail to detect any intrusion attempts, no matter if movement was parallel or perpendicular to detection zones.
Given the passive IR sensor, it is unsurprising the unit did not 'false alarm' on motion outside that might be visible through windows, but worth noting the same movement may erroneously trigger motion in cameras.
Alarm Delay at Longer Ranges
One behavior that was noted: The sensor did not alarm instantaneously at ranges greater than 30 feet. Even with any alarm panel delays turned off, the sensor generally took between 500 ms to 1 second of interior movement to trip alarm at farther ranges. This alarm delay was less at closer ranges, undoubtedly because the 'target' is larger the closer it is to sensor.
This behavior reinforces the general 'detection in layers' principle to maximize response time in event of alarm, where a series of contacts on doors and windows in conjunction with a motion sensor would offer the best intrusion detection performance.
One of the primary sources of false alarms in residential systems, is when motion sensors are triggered by the movement of household pets. To combat this, a 'pet immunity' function omits movement from small masses, generally animals up to 30 - 45 pounds.
In our test, the unit did not false alarm on a medium-sized animal walking through detection zones.
Off for High Security: However, if the sensor is used in commercial spaces where pets are uncommon, or if detection of small masses is potentially important in sensitive areas, the unit's Pet Immunity option can be turned off at the sensor.
The addition of pet detection is a modest increase over the same sensor that lacks it. From internet resellers, unit prices for ISC-BPR2-W12 are:
- With Pet Immunity: ~$15-$20 (This option is designated as WP12)
- Without: ~$10-$15 (Unit designated as W12 only)
Overall, the Bosch Blue Line ISC-BPR2-WP12 is marginally more than the similar Honeywell IS2535 Pet Immune offset which runs ~$7-$15 each. For single family houses or flats, the increase in cost is minor, but for high-volume dealers and systems Bosch sensors generally cost a few dollars more.
PIR Testing Parameters
In terms of evaluation, our test encompassed a non-rigorous, but typical environment for indoor PIR used in both residential and commercial applications.
Testing duration was continuous over the course of 40+ hours and the sensor was connected to a standard Vista 15P intrusion system in its own zone. As typical, sensor power was sourced from the panel and no performance differences were noted running on either mains or battery back-up power.
Pet Immunity was tested using two animals - one being ~15 pounds, the other ~30 pounds. Also, several adults and children were used, ranging from ~50 pounds to ~200 pounds, with no errant detection or missed events during the test.
The sensor was also mounted directly under an HVAC output vent and also a return vent. Temperature deltas of ~15 - 20 degrees of air flowing from or into those vents did not cause false alarms, which is a classic error point especially for older PIR sensors but not an apparent concern for the Bosch unit in our test.
The Blue Line we tested in standard residential conditions show it suitable for covering residential common rooms (typically living rooms or dining areas) and long areas like hallways.
No Missed Alarms: Our test unit did not fail to alarm on motion when it needed.
No False Alarms: Likewise, our test unit did not alarm in error when unneeded, and the pet immunity feature worked well.
Untouted Creep Resistance: While Bosch does not claim the unit is 'creep resistant', or where a normally alarm-size mass moves so slowly it escapes detection by the sensor, we found the unit was sensitive enough to trip on even slight movements from a complete standstill, at even long ranges. For human sized targets, the sensor will not likely be fooled by just moving very slowly through the detection area.
However, the sensor is not without aspects that could be big problems if unrealized:
Wall Mounted Blindspots: The unit's angle of coverage potentially leaves large patches of undetectable area close to the sensor and clearly is best when corner mounted in a room.
Indoor Only: While sealed against insects or dust infiltration, the sensor is not rated for outdoor exposures and rugged temperatures.
Further Reading on PIRs
For details on the general strengths, weaknesses, and technology used in these sensors, see our PIR Detector Selection Guide.