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When it comes to electrical safety, most people know about RCDs and MCBs, but fewer have heard of AFDDs. However, they’re becoming increasingly common in the UK, and in some circumstances, they’re even recommended by the Wiring Regulations.

Here’s what an AFDD is, what it does, and whether you might need one.

🔥 What Is an AFDD?
An AFDD (Arc Fault Detection Device) is a specialist safety device designed to detect dangerous electrical arcs in a circuit and automatically disconnect the power before a fire can start.
✔️ What is an arc fault?
An arc is an electrical spark caused by a fault, usually from:
-Loose or damaged wiring
-Crushed or kinked cables
-Overheated socket outlets
-Rodent damage to cables
-Old or poorly installed wiring
-Loose connections behind sockets or lights
These arcs generate extremely high temperatures — often over 1000°C — and can ignite surrounding materials long before other safety devices detect a problem.

🛡️ What Does an AFDD Protect Against?
AFDDs detect dangerous patterns in the electrical waveform that indicate arcing. They offer protection against:
-Series arcing (within a single conductor)
-Parallel arcing (between line and neutral or line and earth)
-High-temperature loose connections
-Damaged or degraded wiring
-Electrical fires behind outlets or in walls
Traditional protective devices cannot reliably detect these types of faults.

📘 What Do the Wiring Regulations Say About AFDDs?
According to BS 7671:2018 Amendment 2, AFDDs are recommended (but not mandatory in most domestic installations) for circuits supplying:
-Locations with sleeping accommodation
-High-risk residential buildings
-Homes made from combustible construction materials
-Places with vulnerable occupants
For typical domestic homes, they are not compulsory — but many electricians suggest them on circuits where the risk of fire is higher (e.g., ring circuits or areas with older wiring).

🏠 Should You Install AFDDs In Your Home?
AFDDs are worth considering if:
-Your home has older wiring
-You have a thatched, timber-framed, or otherwise high-fire-risk property
-You want the highest level of electrical fire protection available
-You’re upgrading or replacing the consumer unit
-You have concerns about loose connections, damaged cables, or old sockets
Although more expensive than standard breakers, AFDDs provide protection that nothing else currently offers.

💷 How Much Do AFDDs Cost?
AFDDs cost more than standard MCBs or RCBOs. Typical UK prices:
-£80–£150 per AFDD device
-Installation cost depends on your consumer unit and number of circuits
They’re usually fitted as part of a consumer unit upgrade, but can also be retrofitted in newer boards.

🔧 How Are AFDDs Installed?
AFDDs are installed inside your consumer unit by a qualified electrician. The electrician will:
-Identify which circuits need AFDD protection
-Test the existing wiring and load
-Replace the existing MCB/RCBO with AFDD/RCBO combination
-Test and certify the installation
This work is notifiable if part of a consumer unit upgrade.

✅ Summary
AFDDs are an advanced safety device designed to stop electrical fires before they start. While not mandatory in most UK homes, they offer significant protection — especially in older or high-risk properties.
If you’re upgrading your fuse box or concerned about the condition of your wiring, AFDDs may be a worthwhile investment.

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24/11/2025

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