Residual current devices (RCDs) prevent fires by detecting and interrupting fault currents that could generate excessive heat. Here’s the mechanism:
- Current imbalance monitoring: RCDs compare the current flowing into a circuit (live wire) with the current returning (neutral wire). Under normal conditions, these currents are balanced.
- Leakage detection: Faults like damaged insulation or arcing cause current to “leak” to earth, creating an imbalance. Even small leaks (as low as 5-30 mA) are detected.
- Rapid disconnection: Upon detecting a mismatch, RCDs cut power within 25-40 milliseconds, preventing sustained arcing or overheating that could ignite materials.
Enhanced fire protection is achieved through:
- Combined AFCI/GFCI models: Dual-function devices detect both arc faults (sparks) and ground faults (leakage), addressing two primary electrical fire causes.
- Preventing earth faults: By stopping leakage currents before they energize conductive surfaces (e.g., appliance casings), RCDs reduce risks of sparks near flammable materials.
While standard RCDs focus on leakage, models with arc fault detection provide additional protection against faulty wiring/connections.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-do-residual-current-devices-work-to-prevent-fires/
