SDG #295 Bluetooth Hager Arc Fault Detection AFDD ARR MCBs (ARR932U etc)

Arc fault detection devices are becoming a familiar sight in UK consumer units, but Hager’s ARR range adds something genuinely unusual: a Bluetooth radio inside the breaker. This video puts one on the bench alongside the older double-width Hager AFDD/MCB combination to show why the new part is worth the swap, and what the wireless link actually buys you.

The practical case is space. The earlier double-width AFDD has no RCD element, so protecting a circuit properly meant pairing it with a downstream RCBO, eating at least three DIN modules. The ARR packs double pole disconnection, a Type A RCD, thermal overload and overcurrent detection into a single module, with visible current transformers on both the outgoing conductors and the incoming phase/neutral pair.

The Bluetooth side exists mainly because arc detection algorithms are imperfect. Brushed motors, welders and similar loads produce high frequency signatures that look convincingly like a series arc, and simpler analogue AFDDs relying on bandpass filter comparison either nuisance trip or miss real faults. A reprogrammable microcontroller means Hager can push improved arc signatures later, which is a reasonable future proofing argument for installers handing over to a customer.

More immediately useful is the event log. The Hager Pilot app reads back the last 16 trips with cause codes, which turns intermittent nuisance tripping from guesswork into a pattern you can actually chase. The app also stores circuit identification notes and includes a guided AFDD diagnosis routine, which reveals that a resistive load above roughly 1kW is needed before arc detection will act. Two caveats worth noting: an account signup is required, and each unit draws around half a watt continuously, which adds up across a full board.