RCDs in TT, TN and IT Earthing Systems
How TT, TN and IT earthing systems change RCD requirements, loop-impedance sizing and where the insulation monitoring device takes over.
RCD Selectivity: S-Type vs Instantaneous Discrimination
How S-type selective RCDs coordinate with downstream instantaneous devices using the 2x current ratio and time-delay rule from IEC 60947-2 and IEC 61008-1.
RCD Trip Time and IEC 61008 Test Requirements
IEC 61008-1 sets exact maximum break times for RCCBs at IΔn, 2×IΔn and 5×IΔn, plus a slower band for S-type selective devices, and this covers what the numbe...
Type A vs Type B RCD: Which for VFD, EV and Solar
Type A RCDs resolve AC and pulsating DC, while Type B is required wherever a fault can produce smooth DC, covering three-phase VFDs, most EV chargers, and tr...
MCB vs RCBO vs RCD vs RCCB: Key Differences
MCB, RCD (RCCB) and RCBO protect against different faults. This compares what each detects, the 30 mA vs 300 mA sensitivity split, and how Vigi or DS201 add-...
RCD Types AC, A, F, B and SI Explained
A breakdown of RCD Types AC, A, F, B and SI: the waveform each detects, why Type AC is now restricted, and how to size Type B for VFDs, EV chargers and PV.
RCD Sensitivity: 10mA, 30mA, 100mA and 300mA Explained
A breakdown of RCD sensitivity ratings (IΔn) from 10 mA to 300 mA, covering personal versus fire protection, earth electrode sizing, and how to choose the ri...
How an RCD Detects Earth Leakage: Toroidal Core Principle
How an RCD's toroidal core sums line and neutral current to sense earth leakage and trip in milliseconds.
ELCB vs RCD vs GFCI: Terminology Explained
ELCB, RCD, and GFCI describe the same protective function in different eras and regions, and knowing which term applies to your panel avoids costly spec mism...
Main Components of an RCD: Toroidal Core and Test Button
A component-by-component breakdown of what is physically inside an RCD, RCCB and RCBO, from the toroidal sensing core to the test button circuit.
