What is a Thatcham Category car alarm?

What is a Thatcham Category car alarm?
Many new cars are fitted with alarms, immobilisers and other clever devices to improve vehicle security. They both protect your possessions from opportunist thieves and your car itself from being stolen.

But the number of different car alarms and security features on offer, and the corresponding level of protection they give, can be baffling for a new buyer. That’s without even considering the huge number of aftermarket units available.

Thankfully, an institution called Thatcham Research independently rates these different car alarms and immobilisers by category to give consumers a better idea of the role they play.

Officially known as the Motor Insurance Repair Research Centre, the organisation works closely with car companies to set car insurance rates depending on the complexity of security systems, safety and repair costs.

Having an alarm or immobiliser fitted is one of the most effective ways of reducing the risk of car theft. Read more.

Here’s an explanation of the Thatcham category alarms

Thatcham Category 1 – electronic alarm and immobiliser

Systems that fall into this class are the cleverest and most complex on the market. A Category 1 alarm will feature perimeter and ignition detection, and will incorporate movement or glass break and tilt sensors. There’ll also be a siren powered by its own battery supply that will sound if your car gets broken into.

Immobilisers are also a requirement to pass Category 1 tests and have to be passively set – that means without any action from the driver – while a minimum of two operating systems or one control unit used for normal operation must be isolated.

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Thatcham Category 2 – electronic immobiliser

Alarms are not a requirement to be awarded Category 2 Thatcham security status. However, an immobiliser is.

Just like Category 1 systems, a Category 2 device has to isolate at least two circuits or systems, or one vehicle control unit that’s required for the car to run properly. Again, it has to be passively set.

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Thatcham Category 2/1 – electronic alarm upgrade

This Category is achieved if upgrade work is carried out on a Category 2 vehicle.

As long as the car has Category 2 security status, adding an alarm with the above facets from Category 1, the car can be upgraded to group 2/1, potentially lowering your vehicle insurance premiums.

Thatcham Category 3 – mechanical immobiliser

Unlike the Categories above, Category 3 immobilisation devices are mechanical, not electric. This means they are physical devices that disrupt how a car operates.

They are generally easy to set and unset, with the rules stating that they have to isolate a minimum of one operating system required for vehicle use. They can be permanently or temporarily installed. Category 3 devices include steering wheel and gear lever locks.

Thatcham Category 4 – wheel locking devices

Most modern cars fitted with alloy wheels benefit from locking wheel nuts. These make it harder for thieves to steal your wheels, as a special key is needed to remove one of the nuts.

They actually count as a Category 4 Thatcham-approved device, which have to be reliable and durable, have a secure key replacement procedure, feature a traceable product and provide resistance to attack.  

There are a selection of mechanical immobilisers and wheel locking devices available for purchase at the RAC's shop.

Thatcham Category 5 – post-theft tracking and recovery systems

These systems can track the whereabouts of a stolen vehicle, but also have the ability to immobilise the car remotely by capping certain engine functions so the car can be shut down. This function is not permitted on Category 6 or 7 systems, though.

Thatcham Category 6 – stolen vehicle tracking

Trackers with this function can track a vehicle, but don’t permit it to be remotely shut down.

Thatcham Category 7 – stolen vehicle location

Similar to the above, immobilisation of the stolen car from a different location is not allowed.

Q class systems – non-categorised aftermarket systems

These can include aftermarket alarms and immobilisers, vehicle marking features, data recorders, vehicle ID and signalling systems and improved door locks that have not been approved by Thatcham.

The higher Thatcham rating the security systems on your vehicle possess, the more your insurance could come down, as your car should prove harder to steal or break in to.

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