Don't Get Caught! Disable is different from Isolate


Occasionally we hear about someone having issues with the Disable function in AS 7240.2 fire indicating panels.

The AS 7240 Disable function is quite different from the Isolate function on AS 4428.1 panels. The main practical difference is that disabling a device when it is in alarm, will not cancel a brigade call. This is true for all AS 7240-compliant panels because AS 7240 explicitly describes the action of the Disable function.

If a device such as a manual call-point (MCP) is in Alarm, pressing the Disable button will disable that specific device. This ensures that the panel will not initiate any further action if it receives another alarm from the disabled MCP. However, if the panel has already called the fire brigade, disabling the MCP will not cancel the brigade call.

Some users expect the panel to cancel the brigade call as soon as the MCP is disabled. That is what happens when you Isolate a device on an AS 4428.1 panel such as the Pertronic F120A. In addition, isolating or de-isolating a device on those panels would also reset any active alarms.

AS 7240 fire indicating panels such as the Pertronic F220 are legally required (under clause 2.2.10 of AS 4428.3) to have separate manual controls for Silence Alarms, Disable, and Reset.

To visualise the operation of these controls, imagine someone has smashed a manual call point in a building’s car-park. The fire indicating panel automatically sounds the alarms and calls the fire brigade. If you have a Pertronic F220, the panel tells you exactly where the alarm has come from. It won't take long to find out what has happened. If the broken call point is the only problem the user will want to cancel the brigade call.

Press Silence/Resound Alarms to turn off the warning system. Then press Disable to disable the affected call point. At this stage the F220 still has an active alarm from this call point. If you happen to press Disable at this point, you would re-enable the MCP and the panel would go back into alarm.

Instead, press Reset to cancel the alarm. This will cancel the brigade call and leave the call point disabled until it can be reset, repaired or replaced.


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