BS5839-6 Hush Buttons

Around 80% of all UK fire deaths and injuries occur in dwellings. Nowhere is the risk greater than in houses of multiple occupation where a fire in one ‘dwelling’ can quickly spread to another.

Unfortunately, an increased risk of fire means an increased risk of false alarms. Failure to reduce false alarms can lead to unnecessary building evacuations, irate tenants, system vandalism and true alarm signals being ignored.

C-TEC’s Hush Button fire alarm solution tackles all of these issues head on.

Designed to work with widely available Apollo XP95 or Hochiki ESP analogue addressable fire alarm systems, it meets and exceeds the requirements of BS 5839 part 6 (the code of practice for fire alarm systems in dwellings) by providing reliable, fully monitored fire detection, alarm and silencing facilities INSIDE each individual flat or apartment.

How does the system work?

Each Hush Button can be looked upon as a miniature fully monitored, self-powered single zone fire alarm panel that sits and is addressed on an analogue loop (see diagrams below) with the ability to communicate its status back to the host fire panel.

Typically one double gang Hush Button is fitted in each HMO dwelling complete with conventional detectors and sounders to provide occupants with a simple, cost-effective means of invoking two types of ‘hushed’ period, as specified in clause 12.2 of BS 5839 part 6.

The whole system is geared towards reducing unwanted alarms by putting HMO occupants firmly in control of their own fire detection systems without losing sight of the fact its primary purpose is to protect life and property.

Moreover, the fact each Hush Button and its local cabling is monitored means any open circuit, short circuit or tampering fault is relayed to building management via the analogue loop and host fire panel for appropriate remedial action – a feature that is simply not available on existing Mains/battery type alarm systems.

General operation

When the fire alarm system is in its normal state (with no alarm conditions anywhere in the building), power is applied to the Hush Button’s detector circuit, its detector and sounder circuits are continually monitored for faults, and its power LED is lit. In the event of a local alarm condition (when a fire detector within the flat or apartment has triggered), the Hush Button’s local sounder circuit will activate and any output devices connected to it will sound.

If there is no one in the apartment to intervene during a local alarm condition (i.e. if the ‘ Hush’ button is NOT pressed): The local alarm sounders will sound for a period of two minutes. If the local alarm clears within these two minutes, the Hush Button will return to its normal state. If the local alarm is still present after two minutes, the alarm will be signalled to the host analogue fire panel and a general alarm condition will be annunciated around the building as programmed.

If the ‘Hush’ button is pressed DURING a local alarm condition: A hushed period of two minutes will commence starting from when the Hush button is pressed. If the local alarm is cleared within these two minutes, the Hush Button will return to its normal state. If the alarm doesn’t clear, 15 seconds before the hushed period is about to expire, a beeper will sound to inform the occupant that the alarm is about to be signalled to the host fire panel. If the ‘Hush’ button is pressed again during this 15 second period, another two minute hushed period will commence.

If the ‘Hush’ button is pressed when there are no alarms present: A hushed period of fifteen minutes will commence. During this period, power is cut to the local zone so no alarm signals from detectors will be detected (however a manual call point with a suitable resistor, less than 400 ohms, will trigger a full alarm if activated). If the ‘Hush’ button is pressed again during this 15 minute period, power is re-applied to the local zone allowing normal signal processing to resume. 15 seconds before the 15 minute hushed period is about to expire, a beeper will sound to inform the occupant that the local zone is about to be re-powered. If the ‘Hush’ button is pressed again during this 15 second period, another 15 minute hushed period will commence.

Manual call points
If a manual call point is connected to the Hush Button’s detector circuit, provided its resistance when operated is less than 400 ohms, its operation will immediately trigger the Hush Button’s sounder circuit and signal a general alarm condition to the host firepanel.

General fire conditions
If, at any time, the host analogue panel enters a general fire condition, it overrides any hushed state at the Hush Button and turns on its local sounders. Pressing the ‘Hush’ button in a general fire alarm condition WILL NOT silence the local alarm sounders and the dwelling should be evacuated as per the designated fire management plan.

Click here to see how C-TEC's Hush Button solution has consigned false alarms and unnecessary building evacuations to a thing of the past at Boatman Court, a 77 bed student accommodation block in Preston.

What does the standard say?

According to BS 5839 part 6 (the code of practice for fire alarm systems in dwellings) around 80% of all UK fire deaths and injuries occur in dwellings - that’s a frightening 500 fatalities and 14,000 injuries a year.

In a bid to reduce this figure, the standard specifies minimum grades and categories for fire alarm systems in dwellings. For HMO dwellings, it recommends at least Grade D (mains/battery powered smoke/heat alarms) and Category LD2 or LD3 systems (detectors in all circulation spaces forming part of its escape routes). It also acknowledges the need for a BS 5839 part 1 system in all HMO communal areas.

In recent years, there has been a general trend towards installing higher-grade EN54 equipment in HMOs so that a single system covers all of its communal areas and its dwellings in order to give one route of responsibility for all of the site’s fire alarm requirements. Unfortunately, many of these systems compromise BS 5839 part 6 in several key areas. For example, clause 12.2 of BS 5839 part 6 indicates there be provision within each HMO dwelling for:-
(a) silencing unwanted alarms when there is a local fire condition; and
(b) isolating the dwelling’s detectors and sounders when activities are taking place that could cause a false alarm.

On most current single system solutions, silencing the alarm sounders can only be done at the communal fire panel which is usually located outside the dwelling. To initiate this facility, the occupier must first locate the communal panel, enter its secure user mode and work out which button to press - all within two minutes. On this point alone it is clear such systems cannot comply with the clauses nor the spirit of BS 5839 part 6. The Hush Button solution not only has the ability to meet the requirements of BS 5839 part 6 in full, it exceeds them.

• Copies of BS5839-6 can be purchased from the British Standards Institute at www.bsi-global.com

Summary / key features

• Upgrades the level of protection offered in a flat or apartment from Grade D to Grade A
• Provides each individual dwelling with a two-minute silence facility and a 15-minute isolate facility to BS 5839 Part 6 clause 12.
• Reduces the likelihood of unnecessary building evacuations, system vandalism and the possibility of a true alarm signal being ignored
• Fully monitored for open and short circuit faults
• Logging facilities at the main communal panel give full traceability of any problems
• Can be operated by building occupants whilst standing at floor level
• Utilises readily-available cost-effective technology
• Compatible with the fire alarm industry’s leading analogue protocols - Hochiki’s ESP and Apollo’s XP95/Discovery

Technical specifications

* dependent on output current of host panel and devices connected.