How to disable part of a fire alarm system safely

Direct answer

Disablement (also called isolation) temporarily takes part of a fire alarm system out of service — for example a single detector, a zone, or the sounders — typically during building work, cleaning, or hot work that would otherwise cause an unwanted alarm signal. Before you disable anything, get authorisation from the person appointed to supervise the system, agree the smallest scope and the shortest time that will do, put alternative fire precautions in place for the affected area, and tell the occupants and any alarm receiving centre. Record the disablement in the log book when you make it, then reinstate, test and record the reinstatement as soon as the work is complete. The exact key sequence or menu steps are specific to the panel model — refer to the manual for your Hochiki panel.

Applies to

• Products / Models: Hochiki Europe control panels, including the Latitude range (the exact key sequence differs by panel — see your panel manual for the exact procedure)
• Firmware / Version: Not applicable
• Region: UK
• Standards: BS 5839-1

What is disablement and when is it used?

• Disablement (also called isolation) temporarily stops part of the system from generating or acting on a signal — for example isolating a detector before dusty work, or disabling sounders during testing.
• Even with a disablement in place, the evacuate control at or next to the panel should still start the alarm across the building.
• It is a controlled, temporary measure — not a way to silence a recurring problem. A persistent fault or recurring unwanted alarm signal should be investigated, not left disabled — see Why is my fire alarm panel showing a fault or beeping? and How do I reduce false alarms on a fire alarm system?.

What must you do before disabling any part of the system?

• Get authorisation from the person appointed to supervise the fire detection and fire alarm system. BS 5839-1 refers to this as the premises management; under the Regulatory Reform (Fire Safety) Order 2005, the duty holder in England and Wales is the responsible person. Disablement controls should in any case be limited to authorised personnel, per BS 5839-1. On the Latitude range, the disablement menu is only reachable at access level 2, through a panel log-in or the front-panel keyswitch.
• Disable only the minimum part needed (one detector or zone rather than the whole system where possible) and for the shortest time — this is good practice; BS 5839-1 says a purpose-built disablement facility should allow one zone to be disabled without disabling others. Check which function your panel offers for the part you need to isolate. On the Latitude range, for example, zones, individual devices and individual panel outputs can be disabled one at a time, but the loop sounders are disabled as a single group, so isolating "the sounders" there stops them across the whole system. Further isolations may be necessary across  other panels if it is a networked system.
• Put suitable alternative fire precautions in place for the affected area while it is disabled (for example a fire watch). This is a fire risk assessment decision rather than a BS 5839-1 recommendation; BS 5839-1 itself describes measures such as temporarily substituting less sensitive detectors, screening or covering detectors, or disabling with prompt reinstatement, as advised by the person appointed to supervise the system or by a competent person.
• Tell the people who need to know before you start. BS 5839-1 recommends notifying building occupants, and any alarm receiving centre to which fire alarm signals are transmitted, before work on the system that could produce a fire alarm signal. Where the work will disable the link to an alarm receiving centre rather than a detector or zone, BS 5839-1 notes that keeping remote monitoring for the rest of the building is usually preferable to disabling the link altogether.

Steps (general procedure)

1. Confirm authorisation and scope
   • Agree with the person appointed to supervise the fire detection and fire alarm system exactly what will be disabled, why, and for how long.
2. Identify the device, zone or output to isolate
   • Use the panel to identify the specific detector, zone or sounder circuit affected.
3. Disable using the panel's documented procedure
   • Follow the disable/isolate function in the manual for your specific Hochiki panel. Confirm the panel shows the disabled condition. The panel's general disablement indicator stays on while any part of the system is disabled; treat it as a reminder that the system may not behave as expected until everything is restored.
4. Record the disablement in the log book
   • Record what was disabled, the date and time, who authorised it, and the reason — see What should be recorded in the fire alarm log book?.
5. Reinstate as soon as the work is complete
   • Re-enable the device, zone or output following the panel's documented procedure and confirm the disabled indication has cleared. Where monitoring to an alarm receiving centre was disabled, confirm with the centre that signals are being received again before you treat the work as complete. Whatever is disabled should be restored as soon as the work allows; the Latitude operating manual carries this as an explicit warning.
6. Test and log the reinstatement
   • Confirm the reinstated part operates normally and record the reinstatement (date, time, who) in the log book.

What to record in the log book

• What was disabled and why, who authorised it, and the date/time disabled.
• The date/time reinstated and confirmation it was tested as working.
• Who was notified before the work: occupants of the affected area and, where the system is monitored, the alarm receiving centre.

When to contact technical support

• If you are unsure how to disable or reinstate a specific Hochiki panel safely.
• If part of the system has been left disabled and you are not sure how to reinstate it, or the disabled indication will not clear after reinstatement.

Safety note

This article is general guidance for Hochiki Europe products. Design, installation, commissioning, maintenance and modification of fire detection and alarm systems should be carried out by, or under the responsibility of, a competent person in accordance with the applicable standards (for example BS 5839-1 in the UK). Statutory requirements imposed by the relevant enforcing authority also apply. Always refer to the current product manual and data sheet for the exact model before carrying out any work.

Last reviewed: 2026-10-23 — Reviewed by: Hochiki Europe Technical Support