Disabling (Isolating) Fire Systems

A fire detection & alarm system is an assembly of equipment comprising control & indicating equipment, primary and secondary power supply, cabling, fire detectors or other inputs such as pressure switches, flow switches and the like.

This document has been written to provide guidance to people on the risks, hazards, appropriate methods, procedures or actions related to disabling (isolating) zones, detectors, ancillaries or the Alarm Signalling Equipment on a fire detection & alarm system.

This document also describes the risks and hazards associated with disabling (isolating) part or an entire fire system, typically associated with planned or ad-hoc maintenance.


A fire detection and alarm system and automatic fire sprinkler systems (fire systems) are routinely connected to the fire brigade via Alarm Signalling Equipment (ASE). In circumstances such as planned or adhoc maintenance it may be necessary to disable (isolate) part or all of the automatic operation of an alarm signal. This action compromises the integrity of the system and may affect life safety or property protection.

Historically we referred to the term "isolate" to describe the function of limiting, disabling or restricting the normal operation of a fire system. Unfortunately the term "to isolate" does not accurately describe in the mind of people the implications of this action.

The term “disable” is now the preferred method to describe this function, and it establishes in the mind a more accurate description of its function, whereas to “isolate” conjures up less dramatic implications.

In fire alarm & detection system terms, there are multiple methods to “disable” a function such as;

  1. Disable (isolating) a zone, circuit or detector (point)
    This is the most common function applied to disablement. It typically means to stop the normal operation of one or more detectors a zone or circuit from activating the common alarm function(s) of a fire panel. In most cases, disabling a detector or zone does not stop an individual detector from still going into alarm, but it does disable its consequential effects.
    A zone typically represents one or more detectors in a common geographic area, and may include up to 40 heat detectors or up to 20 smoke detectors. Some zones may also be more critical to the function of an entire system, such as dual zone operation of a fire suppression system. By disabling a single zone in this instance may render the suppression system inoperative.
  2. Disable the Alarm Signalling Equipment (ASE)
    This is another method to disable the automatic transmission of an alarm signal between the Fire Indicator Panel (FIP) and the Fire Brigade. On its own, disabling the ASE does not affect the operation of the FIP.
  3. Disabling an Ancillary Output
    An ancillary output of the Control and Indicating Equipment (c.i.e.) is a function of a FIP that is used to control one or more ancillary functions such as an Occupant Warning System (OWS), Smoke & Heat control measures of Mechanical Ventilation Systems, Magnetic Door Hold Open Devices, and the like.


Fire systems are installed to provide a reasonable standard of safety for occupants and visitors to the building. This standard of performance is determined by Legislation, Codes and Standards.

Any function that reduces this standard of performance can therefore affect the safety of the occupants and visitors to the building.

In addition, building owners take out insurance to protect their investment in the building that may also be compromised by any reduction in the standard of performance of the fire systems in the building.

Contamination & Nuisance Alarms

In general terms the definition of a false alarm (also known as a nuisance alarm) is any alarm from the fire detection & alarm system such as deceptive phenomena, contamination, interference, component failure or water damage.

The most common reason we are requested to disable a part of a fire system is due to the possibility of a false alarm due to contamination due to dust. This could be due to a maintenance or construction activity in the area.

The market typically responds to these requests by isolating the detectors in the are from the control panel, leaving the detectors exposed to contamination.

While this is a common industry practice, it simply defers the potential for a false alarm to a later stage.

Best Practice

Firewize believes that building owners and agents of building owners need to take precautions to limit the risks associated with fire systems that have been partially or completely disabled. Here is a list of 9 things you can implement to limit or control your risk exposure.

9 Things you can do to limit or control your risk exposure
  1. Inspect the fire systems in each building on a daily basis for any condition that may affect the intended operation of the system;
  2. Record any condition in a register detailing the date & time the condition was observed and take appropriate actions to rectify;
  3. Limit access to controlling the fire systems to only those people who are competent to carry out work on the system;
  4. Ensure all systems are maintained by a competent contractor who understands the intended operation of the system;
  5. Ensure all contractors are inducted into the building, and understand the standard operating procedures related to the fire protection systems;
  6. Protect all fire detectors from contamination due to maintenance, cleaning or building works;
  7. Limit the extent or scope of any required disablement to only the affected area and for the least amount of time practicable;
  8. Create and maintain a register of required disablements with a clearly defined scope, start and end time for each activity. The register should also include details of the person responsible for the disablement;
  9. Carry out a periodic inspection, test and survey of your fire systems in accordance with the relevant requirements of Australian Standard AS1851.

This list is not exhaustive but does provide a framework of thinking to assist building owners and agents of owners in managing their fire systems.

More Information

Firewize has a range of materials including Guides, Forms Templates and Procedures that are available by written request. If you need more information about anything raised in this document, send us a request in writing and we will respond accordingly.

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