How AFDD Arc Fault Detection Devices Work

What is an Arc Fault?

Simply put, an arc fault is electricity “jumping” or “sparking.” Under normal conditions, electric current flows obediently along the wires. But when wire insulation ages or gets damaged, or when connections become loose, the current takes an alternate path—it jumps across air gaps, creating a bright spark. This is an arc fault.

How Dangerous Are Arc Faults?

Arc faults generate extremely high temperatures, with core temperatures exceeding 3000°C—hotter than welding! They can instantly ignite surrounding combustible materials like wood, fabric, and plastic. Statistics show that a significant portion of electrical fires are caused by arc faults. What’s even more frightening is that series arcs (“loose connections” in the circuit) carry very small currents that standard circuit breakers cannot detect, yet the fire hazard is very real.

How Does AFDD “See” Arc Faults?

AFDD (Arc Fault Detection Device) acts like a “fire eye” for your electrical circuits. It contains highly sensitive sensors that monitor current waveforms in real-time. Normal current waveforms are smooth and regular, while arc current shows “sawtooth” mutation characteristics. AFDD uses intelligent algorithms to analyze these waveform features, identifying dangerous arcs within milliseconds and cutting off power immediately.

Series Arc vs. Parallel Arc

• Series Arc: Occurs along the same conductor, such as internal wire breakage or loose connections. The current path gets “stretched,” creating an arc.
• Parallel Arc: Occurs between the live wire and neutral wire, such as when damaged insulation causes the two wires to touch. This type of arc carries more energy and is more dangerous.

AFDD can effectively detect and protect against both types of arc faults.

Why Does Your Home Need AFDD?

Traditional circuit breakers and RCDs (residual current devices) only protect against overload, short circuits, and leakage—they are powerless against arc fault fires. AFDD specifically fills this safety gap. It’s especially suitable for older homes, wooden structures, and households with high-power appliances. Installing an AFDD is like adding a “firewall” to your electrical system, giving your family greater peace of mind.