Most electrical fires do not start the way people imagine them.
They do not start with a loud fault, a tripped breaker, or a visible sign. They start quietly — inside a wall, inside a conduit, inside the insulation of a cable that has been rubbed, pinched, or aged to the point where its integrity has failed.
The fault that causes them is called an arc fault. And standard protection devices — MCBs, RCCBs, even MCCBs — are not designed to detect it.
What is an arc fault
An arc fault is an unintended electrical discharge between two conductors. It occurs when a gap develops in a circuit — at a loose terminal, a damaged cable, a point of insulation failure — and current jumps across that gap rather than flowing through it.
The energy released in that arc is significant. Temperatures at the arc point can exceed 6,000°C. This is enough to ignite surrounding insulation, dust, or structural materials. The arc may occur intermittently, for milliseconds at a time, over hours or days before any fire develops.
During that time, an MCB registers nothing abnormal. The current volume is within its rated range. There is no overload. There is no short circuit in the conventional sense. The MCB does not trip, because the MCB is not measuring what is going wrong.
What an AFDD does differently
A Residual Current Circuit Breaker monitors the balance between the current flowing out through the live wire and the current returning through the neutral wire. In a healthy circuit, thesAn Arc Fault Detection Device continuously analyses the electrical waveform in the circuit it protects. It uses a microprocessor to distinguish between the normal variations in a circuit’s waveform — the kind produced by switches, motors, and dimmers — and the erratic, high-frequency signatures that indicate a dangerous arc.
When it detects an arc fault pattern, it disconnects the circuit. The arc is extinguished before it can initiate ignition.
This capability fills a protection gap that has existed in electrical installations for decades. MCBs respond to current volume. RCCBs respond to current imbalance. AFDDs respond to current behaviour — specifically, the behaviour that precedes electrical fires.
Where arc faults are most likely to develop
Loose terminal connections — common in older installations or those that have undergone repeated modification — are a primary source. Cables running through walls and under floors, subject to physical stress over years of building movement, are another. Ageing insulation on
frequently used appliances is a third. In each case, the degradation is gradual and invisible. The standard visual inspection does not catch it.
High-risk environments include older residential buildings where wiring has not been replaced, commercial properties with dense cable runs, and any installation where electrical loads have been added progressively without full rewiring.
AFDD as part of a layered protection system
An AFDD does not replace an MCB or an RCCB. It completes the protection stack. The MCB guards against overload and short circuit. The RCCB guards against earth leakage and electrocution. The AFDD guards against arc-induced fires.
All three threats are real. All three require a dedicated device to address them.
Fairtek’s AFDD integrates overcurrent, earth leakage, short circuit, and arc fault protection into a single device. It is designed to be installed on the DIN rail alongside existing MCBs and RCCBs — no significant changes to the distribution board are required.
The number that matters
Electrical fires account for a substantial share of structural fires in India every year. A large proportion of them originate from faults in wiring and distribution equipment. Many of them occur in buildings where the MCB did not trip, because the MCB had nothing to trip on.
An AFDD would have responded. In most cases, before any fire began.
That is what it was built for.