What you need to know about arc fault detection devices (AFDDs)

Electrical fires account for around half of all fires in the UK, with nearly 20% caused by electrical distribution in the wiring, cabling and plugs, according to the charity Electrical Safety First.

Often the reason for an electrical fire is a fault causing an arc within cables and connections. Although using circuit breakers, fuses and RCDs greatly reduces the risk of fire, these cannot detect faults – so how do you ensure that a circuit does not cause a fire?

An arc fault detection device (AFDD) will not only detect the dangerous arc but also then go on to disconnect the electrical supply, reducing the risk of fire. AFDDs can be installed in all types of premises but are particularly recommended in buildings where people sleep or where priceless objects are stored, as well as any buildings which are at higher risk of fire because of the materials they are made from or the nature of the objects that are stored within them.

Installing an AFDD gives additional protection because it can detect dangerous low level arcing that is not picked up by other means and which is caused by issues such as damaged cables or insulation, or loose connections. Because these issues often have their origin in external influences that cause weak points in the installation, such as rodent damage, loose plug sockets or ageing, it means that arc faults usually develop over time, generating high temperatures and beginning to burn the installation.

How do AFDDs work?

Whereas circuit breakers provide protection against short circuits and overloads and therefore do not protect against arc faults, AFDDs use technology to monitor the flow of electricity and detect any anomalies in waveforms caused by dangerous arcs.

AFDDs are compact, modular devices which are installed on the final electrical circuits that supply socket outlets. They are designed to constantly monitor patterns in the electrical current and use algorithms to identify any potentially dangerous anomalies. They only detect arcs which are unsafe as opposed to those which are working correctly but nevertheless produce harmless sparks, such as when a switch is flicked on.

When an AFDD detects a dangerous pattern in the electrical waves, it immediately trips, disconnecting the circuit from the electrical supply and thus preventing further risk from the faulty arc.

The only drawback currently with AFDDs is they do not detect fault arcs on ring mains due to the return path, but this is something that is under review.

Our expert team at DRF has extensive experience of electrical fire safety and the installation of fire safety measures including AFDDs. To find out more about AFDDs and choosing the correct one for your electrical circuit, call us on 0113 257 8212.