Iskra d. d.

Residual Current Circuit Breakers FI, NFI

With a residual current circuit breaker (RCCB) the following protective measures are available: fault protection, protection against fire and additional protection in case of direct contact.



  • Isolating function
  • Additional colour display of the position of main contacts (red – contacts closed, green – contacts open)
  • A terminal shape prevents connection of a conductor outside the connection area
  • Types:
  1. Type A (designated NFI) – sensitive to alternating and pulsating dc residual operating currents
  2. Type AC (designated FI) – sensitive only to alternating residual operating currents of a sine wave form
  3. Type F (designated NFIF) – tripping is ensured as for type A and in addition for residual currents with mixed frequencies that can result from single-phase electrical loads with frequency inverters.
  4. Type B (designated NFIB) – tripping is ensured as for type A and in addition for smooth d.c. residual currents, residual d.c. currents which may result from rectifying circuits and high frequency a.c. residual currents.

  • Special versions:
  1. Type S: A switch with a delayed break enabling selectivity regarding a general type and a short-time delayed type (type G)
          connected on the load side
  2. Type G: a short-time delayed breaking characteristic (a min. non-actuating period is 10 ms)
  3. FIR-FIT combination: It is used for a protection in circuits where operational currents are higher than rated currents of residual current circuit breakers.



Catalogue NFI, FI

Catalogue NFIB

Catalogue NFIF

EC Declaration of Conformity for FI_NFI

VDE Certificate for NFI

VDE Annex to NFI Certificate

VDE Certificate for FI

EAC certificate


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