Residual-current device (RCD)
Interruptor diferencial (protección por corriente residual)
- Date
- c. 1950-1960 · confidence low
- Place
- Vienna, Austria
- Credited to
- Gottfried Biegelmeier (and Siemens predecessors)
- Field
- Matter & energy
⚠️ Disputed: the sources disagree.
What it is
A device that compares the outgoing and returning currents of an installation and opens the circuit within milliseconds if there is an earth leakage of about 30 mA. It sharply reduced domestic electrocutions.
Fault-voltage protection switches existed from the 1920s-30s (Siemens, Kiefer); the residual-current type, credited to Biegelmeier in Vienna, spread in the 1950s-60s. The date is approximate.
What it led to
- mandatory protection in bathrooms and kitchens in many countries
- 30 mA RCDs for personal safety
- IEC residual-current protection standards