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Technical guide

Guide to RCCB Types AC, A, F and B

RCCB types AC, A, F and B differ by the smooth or pulsing DC fault they catch: AC for pure AC, A for mixed, F for frequency-drive, B for universal. Pick by the load waveform, not the name.

NEUTRON Engineering TeamUpdated September 1, 20265 min readTechnical application guidance
Generic residual-current devices arranged for type comparison
Fig. 0 — Technical application context for this guide.

Key takeaways

  • RCCB types AC, A, F and B differ by the smooth or pulsing DC fault they catch: AC for pure AC, A for mixed, F for frequency-drive, B for universal. Pick by the load waveform, not the name.
  • Treat headline ratings as an engineering input, then confirm the final configuration against the project drawings and applicable local requirements.
  • Keep the approved component list, critical interfaces and required test or document deliverables visible before production begins.

1. What the four types catch

Type AC trips on residual AC; type A adds mixed-frequency pulsating DC; type F adds high-frequency pulsating DC; type B adds smooth DC up to 6 mA/Hz of the supply.

The load waveform, not the label, decides the safe choice.

Electrical test context for residual-current protection devices
Fig. 1 — Equipment relationship used in the technical explanation.

2. Matching type to load

A type-A RCCB on a PV inverter and a type-B on a medical IT system close the loop the spec needs.

  • Type AC — general sockets and pure-AC loads.
  • Type A — mixed AC/DC, EV chargers, PV inverters.
  • Type F — frequency drives and class-1 appliances.
  • Type B — medical and data centres with smooth-DC fault.

3. Standards and NEUTRON RCCBs

Built to IEC 62423 with the type-specific trip curves, NEUTRON RCCBs carry CE and CB certification, up to 1000 V, IP20 to IP65.

RCCB type selection sequence from waveform through circuit application
Fig. 2 — Engineering review sequence.

Technical diagram shown at a readable responsive scale.

4. Common mistakes when specifying

  • Using type AC on a PV inverter — misses the DC fault.
  • Using type A where smooth DC appears — under-trips.
  • Ignoring the frequency drive — F or B needed, not AC.

Project paths

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Engineering boundary

This is general technical guidance, not a substitute for local electrical code, the applicable standard, product datasheets or a qualified engineer's design review. Confirm ratings and final configurations against the actual project.

Bring the project inputs to the first review.

NEUTRON can review the application context, electrical envelope, enclosure conditions and document requirements related to guide to rccb types ac, a, f and b before quotation.

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NEUTRON Engineering TeamPower distribution and new-energy equipment for project-based export supply.

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Technical review note

Converted from the approved Period 01 source article for Guide to RCCB Types AC, A, F and B. Editorial instructions, duplicate anchor placeholders and embedded publishing directions were removed; the technical body is retained for educational use.