If my alarm ever goes off, one of the first things I want to know is simple: how long does a burglar alarm go off for?
It matters because I want it loud enough to scare off an intruder. But I also don’t want it ringing for hours and upsetting the neighbours.
In this guide, I’ll explain:
- How long alarms usually sound in the UK
- What the legal time limit is
- What happens with older systems
- What to do if your house alarm keeps going off
- How to make sure your system is set correctly
How Long Does a Burglar Alarm Go Off For in the UK?
In most modern systems, the alarm will sound for around 15 to 20 minutes.
That answers the common questions:
- how long does a house alarm sound
- how long does a burglar alarm ring
- how long do intruder alarms go off for
The standard cut-off time in the UK is typically 20 minutes.
After that, the external siren stops automatically. The system itself may still be armed, but the noise will not continue.
This is sometimes called the alarm cut off time UK, or external alarm bell time limit.
Why Is There a Time Limit?
The main reason is noise control.
Under UK noise regulations, alarms must not cause continuous disturbance. If an alarm rings for too long and no one responds, it can become a statutory nuisance.
If ignored, this can lead to:
- A burglar alarm noise complaint UK
- A warning from the local council
- Possible fines
- The council arranging forced entry to silence it
That’s why modern systems are programmed with a set time limit.
Twenty minutes is long enough to:
- Alert neighbours
- Scare off most intruders
- Give monitoring centres time to respond
But short enough to prevent unnecessary disruption.
What Happens with Older Alarm Systems?
Older alarms sometimes did not have automatic cut-off timers.
That meant they could keep ringing until:
- Someone manually reset them
- The battery ran out
In some cases, they would ring for hours.
If you still have an older system, it may not follow the usual burglar alarm time limit of UK standards. This is one reason many homeowners choose to upgrade.
If you’re unsure whether your system has a timer, it’s worth checking with a professional.
Is 20 Minutes Enough to Stop a Burglar?
Yes. In most cases, it is.
Burglars want quick and quiet entry. A loud siren draws attention immediately. Most intruders will leave within minutes once an alarm sounds.
An alarm is designed to:
- Shock the intruder
- Attract attention
- Trigger a response
It is not designed to ring endlessly.
If your system is professionally installed and maintained, that 15–20 minute window is more than enough.
What If My House Alarm Keeps Going Off? How Do I Stop It?
If your house alarm keeps going off, the problem is usually one of these:
- Low battery
- Faulty sensor
- Poor installation
- Incorrect sensitivity settings
- Environmental triggers such as draughts or loose fittings
Here’s what I recommend:
Step 1: Check the battery
Many false alarms are caused by backup batteries failing.
Step 2: Look for sensor issues
Movement sensors can sometimes be triggered by pets or shifting objects.
Step 3: Get a professional service
Regular maintenance prevents most false alarms.
If your system needs adjusting or replacing, professional intruder alarm installation makes a huge difference.
A properly installed system rarely causes repeated nuisance alarms.
Monitored vs Non-Monitored Alarms
The ringing time applies to the external siren. But what happens behind the scenes depends on your setup.
Non-monitored alarm
- Siren sounds
- Stops after 20 minutes
- No automatic contact unless set up via app
Monitored alarm
- Siren sounds
- Monitoring centre is alerted immediately
- Keyholders or response team contacted
If you want better protection, adding CCTV to your alarm system is a smart idea. Many homeowners choose to install CCTV cameras alongside their alarm for extra security and peace of mind.
This means even after the siren stops, the incident is still being recorded.
Real Example
Let’s say you’re away for the weekend.
An intruder triggers your alarm at 2am.
What happens?
- The siren sounds immediately
- It rings for up to 20 minutes
- Neighbours are alerted
- If monitored, you receive a call
- The alarm cuts off automatically
Even though the noise stops, the system remains armed unless disarmed properly.
That is exactly how it should work.
Common Mistakes People Make
I often see these issues:
- Leaving old systems unserviced
- Ignoring low battery warnings
- Not updating contact details for keyholders
- Installing DIY alarms without proper setup
- Turning sensitivity too high
These mistakes can lead to repeated false alarms and neighbour complaints.
Do You Need to Check or Upgrade Your Alarm?
If you’re unsure how long your system rings for, or if it keeps triggering unexpectedly, it may be time to have it checked.
At Forrest Security Systems, I focus on installing reliable, compliant systems that protect your property without causing disruption. Whether you need burglar alarms or a full security system.
I make sure every installation follows UK alarm time limit regulations and works exactly as it should.
If you’d like advice, a service check, or a new installation, contact us.
I’m always happy to help you secure your property properly and give you peace of mind.
