The Wisualarm DHI-HY-SA5MB is a mains-powered photoelectric smoke alarm that draws its primary power from a permanent 230V mains connection and includes a replaceable 9V alkaline battery as standby backup. Its photoelectric sensing chamber is suited to general residential rooms — living rooms, bedrooms, hallways and landings — wherever early smoke detection is needed.
The alarm's 85dB(A) sounder gives clear audible warning alongside a visual LED indicator, and it interconnects by wire with up to 24 other Wisualarm mains-powered smoke and heat alarms, so one triggered unit sounds every linked alarm across the property. Test and silence functions are supported via any working infrared remote control, useful for ceiling-mounted units out of easy reach.
Photoelectric
Sensor Type
≥85dB
Alarm Volume @ 3m
9V
Replaceable Battery
24
Max Interconnected Units
Grade D2
BS 5839-6 Classification
Mains + Backup
Power Supply
Grade D2 — Familiar Replaceable Battery
The SA5MB's replaceable 9V alkaline standby battery classifies it as a Grade D2 device under BS 5839-6. This is widely specified in rental properties and retrofit installations, where a familiar, low-cost 9V battery is straightforward for landlords or occupants to source and replace.
Annual Battery Check Recommended
The standby 9V alkaline battery should be checked and replaced as part of an annual maintenance visit, alongside testing the alarm's own test and silence function, to ensure backup power remains available during any mains interruption.
Photoelectric Smoke Detection — Not for Kitchens
This is a smoke alarm, not a heat alarm, so it should not be fitted in kitchens or other rooms prone to cooking fumes and steam, which can trigger false alarms. For those spaces, use a Wisualarm heat alarm such as the HT5MA or HT5MB instead.
Replaceable 9V Standby Battery
A standard 9V alkaline battery provides backup power during mains interruptions and can be replaced by any competent person without specialist tools.
Photoelectric Smoke Sensing
A photoelectric sensing chamber gives fast, reliable detection of visible smoke while resisting many of the nuisance triggers that affect other detection types.
Hardwired Interconnect, 24 Units
Connects to up to 24 other mains-powered Wisualarm smoke and heat alarms over standard interconnect wiring, so one triggered alarm sounds every linked unit in the property.
IR Remote Test & Silence
Supports test and 9-minute silence functions via any working infrared remote control, letting installers and occupants manage the alarm from floor level rather than a ceiling-mounted button.
85dB Audible Alarm
A built-in sounder delivers ≥85dB(A) at 3 metres, loud enough to alert occupants throughout a typical room or hallway.
Clear LED Status Reporting
A green/red LED indicator reports standby and alarm conditions at a glance, so status is clear without needing to open the unit.
Product Identity
Model number
DHI-HY-SA5MB
Brand
Wisualarm (by Dahua)
BS 5839-6 Grade
Grade D2
Detection
Sensor type
Photoelectric
Sampling period
10 s
Alarm response threshold
0.2dB/m–0.3dB/m
Power
Primary supply
AC 100V–250V, 50/60Hz (mains)
Standby battery
Replaceable 9V alkaline battery
Alarm Output
Alarm volume
≥85dB(A) at 3 metres
Alarm mode
Visual and audible alarm
Silencing
Yes — 9 minutes, including via IR remote
Indicators
Standby
Green LED remains lit
Alarm
Red LED flashes once per second
Interconnection
Wired interconnect
Up to 24 hardwire interconnected units
Installation
Installation
Ceiling mount
How often does the backup battery need replacing?
The 9V alkaline standby battery should be checked and replaced as part of routine annual maintenance, so backup power remains available during any mains interruption.
How many alarms can be linked together?
Up to 24 Wisualarm mains-powered smoke and heat alarms can be hardwired together on the interconnect line, so that any single alarm triggering sounds every linked unit in the property.
Is this alarm suitable for a kitchen?
No. This is a photoelectric smoke alarm, and cooking fumes and steam can trigger false alarms. Fit a Wisualarm heat alarm, such as the HT5MA or HT5MB, in kitchens and similar spaces instead.
What's the difference between the SA5MA and SA5MB?
Both are mains-powered photoelectric smoke alarms with the same 24-unit interconnect capability. The SA5MA uses a sealed rechargeable lithium battery, while the SA5MB uses a replaceable 9V alkaline battery.
Can this alarm be silenced from floor level?
Yes, the SA5MB can be tested and silenced using any working infrared remote controller, avoiding the need to reach a ceiling-mounted unit directly.
BTU & WATT Calculator
Room Dimensions
Room Type
Living Room
Bedroom
Kitchen
Bathroom
Conservatory
Hallway
Glazing Type
Single Glazed
Double Glazed
Triple Glazed
External Walls
0 Wall
1 Wall
2 Walls
3 Walls
4 Walls
Insulation Level
Poor
Average
Good (New Build)
Required Heating
0
Watts
0
BTUs
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