What Happens When a Burglar Alarm Goes Off?

The sequence, second by second

• 0s — a detector triggers; entry-route zones start the entry timer instead of alarming immediately
• 0–5s — full alarm: external sounder and strobe activate, internal sounders too on most systems
• Seconds — app push notifications go out; monitored panels transmit the activation with zone data to the ARC
• 1–3 min — ARC operators act on confirmed/unconfirmed status: keyholder calls in order, police contact on confirmed URN activations
• 20 min — external siren times out (UK noise limit); strobe continues marking the property
• Until reset — the panel holds the event and log; monitored systems record every step with timestamps

What should you do when your alarm goes off?

If you're away and get the notification: check cameras if you have them, call a neighbour or keyholder — and don't walk into the property alone if there's any sign of entry; call 999 if you see evidence of a crime in progress. If you're home: the keypad shows the zone; treat an unexpected interior activation at night seriously — make noise, put lights on, and call 999 rather than investigating silently. Most activations resolve as known causes; treat the unexplained ones with respect.

What if nobody responds at all?

This is the gap bells-only systems live with: after 20 minutes the street is quiet again and only the strobe and log remain. Burglar interviews are clear that sirens shorten intrusions — most leave within minutes — but an empty property with no response invites return visits. If your notifications routinely go unanswered (work shifts, travel), that's the practical case for ARC monitoring or at least a professional keyholding service.