Sound Systems and Intercom Systems

AUST – The Building Code of Australia requires high rise buildings to have a sound system and intercom system (SSIS) complying with AS 1670.4-2004 ‘Fire detection, warning, control and intercom systems – System design, installation and commissioning – Sound systems and intercom systems for emergency purposes’, for emergency purposes. This installation is required by the Building Code of Australia when the building height exceeds 25m in effective height.

A SSIS installation under AS 1670.4-2004 ‘Fire detection, warning, control and intercom systems – System design, installation and commissioning – Sound systems and intercom systems for emergency purposes’ comprises a master control panel usually interfaced to the buildings fire panel, warden intercom points, manual call points, a master warden control point and warning speakers distributed throughout the building to achieve a defined level of audibility above background noise, SSIS training for the occupiers is essential. In areas having high ambient noise levels, the audible warning system shall be reinforced by visual warning devices as well.

The following illustration depicts the requirements for the speaker location.

The SSIS system goes into operation following an alarm being processed by the fire indicator panel (FIP). The fire indicator panel provides an output to identify the affected level/ zone in the building to the master evacuation control panel (M.E.C.P). The system functions to produce general alert and evacuation tones as required for individual evacuation zones in the building. The alert tone is required to time out and be replaced by the evacuation tone. The code specifies the frequency profile for the tones.

In most multi-storey buildings, except for carparks, each storey will be an evacuation zone as each storey is a different fire compartment under the BCA. A carpark is usually a single fire compartment as each carpark level is connected by vehicle ramps therefore it is permitted to function as a single zone.

A typical installation will also incorporate a verbal address facility, preset spoken message response, system status and faults and has a dedicated battery backup power supply.

In multi storey buildings, the SSIS can only function to its optimum when an Emergency Control Organisation (ECO) is effective with duties of chief warden and wardens being allocated. These persons must be correctly trained and regular evacuation drills need to be conducted.

AS 1670.4 requires automatic execution of a building evacuation alarm and the alert signal set to “0” seconds in time unless the emergency planning for the building has considered and specified a longer period.

A SSIS system provides typically, the first priority to the zone in alarm (Fire affected floor) which receives an alert tone quickly followed by an evacuation tone. The second evacuation priority is usually given to two zones (storeys) above the “fire affected floor” and the third priority is the floor immediately below the initial fire affected zone (floor). Other levels are then evacuated in a logical order of priority using the same sequence of “two up, one down”.

Depending on the actual fire circumstances, the SSIS systems installed in a multi storey building may continue to go into alarm for zones above the initial fire affected floor. This means that zone priorities will move according to the zones going into alarm, as registered at the fire indicator panel, and as the master evacuation control panel automatically responds to the signals received from the fire indicator panel.

The alarm priority to other zones or levels in the building can also be controlled by the chief warden or fire brigade through SSIS as circumstances require, hence the importance to integrate an E.C.O. into the building.

It is worth noting that AS 1670.4 is not very specific as to the sequence of alarm to zones or levels so a logical system would have an override function to allow the chief warden to manage total building evacuation in a timely manner. It is possible that total evacuation of the building will not need to occur if the initial alarm and fire is isolated to its point of origin.

The operation of passenger lifts in a multi storey building must also be considered as they could be in use when an alarm occurs.

The passenger lifts installed in buildings are required to have fire service controls and additionally for buildings over 25m, the lift(s) must function as a stretcher lift and as an emergency lift. (Stretcher lifts are required in buildings exceeding 12m in effective height under the Building Code of Australia).

AS 1735.2 details the operation of a lift fitted with fire services controls and the recall fire service switch. The Building Code of Australia requires a lift warning sign to be provided at each lift call station which states “Do Not Use Lifts If There Is A Fire” but relies on the lift codes to detail physical functions and operations of lifts when there is a fire alarm.

In the event of a fire alarm, lifts can be manually activated to park at a nominated floor (ground floor) with the doors open. This function is called the “recall fire service switch”, and is in addition to the fire service controls required within the lifts by both the Building Code of Australia and the lift code. The lift code requires a person to key either switch to the “on” position. The recall fire service switch function (only) will call all lifts to the ground floor. The fire service control within the lift cars are not overridden by this function when they have been keyed to the “on” position.

The operation of the recall capability is reliant on the chief warden or fire brigade intervention as AS 1735.2 does not permit a fire alarm in the building to activate this lift function. The key to activate this facility is required by the lift code to be kept on the ground floor.

The integration of lift functions with fire alarms is not well addressed by the Building Code of Australia and additional response initiatives by the building owner(s) will be required. Considerations will include putting in place an Emergency Control Organisation to initiate occupant evacuations through functions and duties of a chief warden who must be remotely alerted to any alarm in the building and to respond accordingly.

This can be achieved by installing additional alarm notifications so that the chief warden is alerted to a fire alarm together with the provision of fire services lift control key(s) on the ground floor foyer and in the fire control room.