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Type F vs Type B RCD for EV Chargers
Type F and Type B RCDs are not two price levels of the same device. They are designed for different residual-current waveforms. For an EV charger, Type F can be used only when the complete arrangement—including suitable DC residual-current detection—is permitted by the EVSE manufacturer and local rules. Type B covers smooth DC residual current within its declared characteristics and may be required when that DC protection is not otherwise provided.
Краткий ответ: choose Type B when the EVSE can produce smooth DC residual current and does not include a suitable 6 mA RDC-DD, or when Type B is specified. Choose Type F plus an IEC 62955-compliant RDC-DD only when the charger documentation and installation rules support that combination. Charger power and phase count alone do not decide the RCD type.
Type F vs Type B RCD: Quick Comparison
| Selection point | Type F RCD | Type B RCD |
|---|---|---|
| Sinusoidal AC residual current | Detected | Detected |
| Pulsating DC residual current | Detected within Type F characteristics | Detected |
| Composite-frequency residual current | Designed for specified single-phase converter waveforms | Covers the broader Type B characteristics |
| Smooth DC residual current | Not a substitute for Type B; needs suitable DC detection where required | Detected within the device’s declared Type B characteristics |
| 6 mA RDC-DD | May be part of the approved EVSE protection arrangement | Normally not needed to protect the Type B RCD from DC blinding |
| Typical decision | EVSE explicitly permits Type F with RDC-DD | No suitable RDC-DD, uncertain waveform, or manufacturer requires Type B |
| Стоимость | Often lower device cost | Usually higher device cost |
| System dependency | Depends on the RDC-DD and switching arrangement | More protection is contained in the RCD itself |
What Type F Actually Detects
Type F RCDs include Type A capabilities and are designed for additional composite residual-current waveforms associated with certain single-phase equipment using frequency converters. They also have defined behaviour with specified smooth DC superposition. This can make Type F more suitable than Type A for some inverter-driven appliances and EVSE designs.
Type F is not a general smooth-DC RCD. If an EV charging fault can produce a smooth DC residual current that would impair Type A or Type F operation, the installation needs a suitable RDC-DD or a Type B solution according to the equipment instructions and local rules.
What Type B Adds
Type B RCDs cover the residual-current waveforms specified for Type F and add smooth DC and other Type B waveforms. This broader capability is useful for equipment containing rectifiers, inverters and multi-phase power converters where smooth DC residual current may occur.
Do not describe Type B as detecting only “smooth DC up to 6 mA.” The rated residual operating current and Type B operating characteristics are defined by the product and standard. The 6 mA value is commonly associated with an RDC-DD used to initiate disconnection before DC can impair a Type A or Type F RCD.
How a 6 mA RDC-DD Changes the Decision
IEC 62955 applies to residual direct current detecting devices used for permanently connected Mode 3 AC charging stations. Depending on its design, the RDC-DD monitors or protects and initiates disconnection through the EVSE’s switching system when the specified DC residual-current condition occurs.
- Confirm the charger declares an IEC 62955-compliant RDC-DD.
- Check whether it is an RDC-MD or RDC-PD and how disconnection is achieved.
- Follow the EVSE manual’s required upstream RCD type.
- Verify any automatic self-test or monitoring function.
- Record the dependency so that a future charger replacement triggers a protection review.
A generic “6 mA DC protection” label is not enough for design approval. The declaration, installation manual and exact model must describe the function.
Selection Flow for an EV Charger
| Шаг | Вопрос | Результат |
|---|---|---|
| 1 | Does the EVSE manual require Type B? | Use Type B and follow the specified ratings |
| 2 | Does the EVSE include a compliant 6 mA RDC-DD? | If yes, Type A or Type F may be permitted; continue checking |
| 3 | Does the manual specifically call for Type F? | Use Type F only with the documented DC-protection arrangement |
| 4 | Can smooth DC occur without suitable disconnection? | Use Type B or the solution required by local rules |
| 5 | What IΔn, poles and current rating are required? | Select the exact RCCB/RCBO and overcurrent arrangement |
| 6 | Are upstream RCDs installed? | Verify type compatibility, sensitivity and time selectivity |
Type F + RDC-DD vs Type B: Installation Comparison
| Installation issue | Type F + RDC-DD | Тип B |
|---|---|---|
| Number of functional elements | RCD plus EVSE DC detection and switching | Type B RCD plus required overcurrent protection |
| Ввод в эксплуатацию | Verify RCD and RDC-DD/disconnection function | Verify Type B RCD operation and complete circuit protection |
| Charger replacement | New charger must retain the approved RDC-DD arrangement | Still review current, phases and manufacturer requirements |
| Fault diagnosis | Check both the RCD and EVSE DC-detection system | Check the Type B device, EVSE and circuit |
| Board space | Can use a compact external Type F RCBO | Depends on available Type B RCCB or RCBO product |
| Техническое обслуживание | Includes EVSE monitoring and switching dependency | More residual-current functionality is in one protective device |
Сценарии применения
7 kW Single-Phase Home Charger
If the wallbox includes an IEC 62955-compliant RDC-DD and permits Type F upstream, a suitably rated Type F RCBO can be a compact option. If the DC-detection function is absent, unclear or the manufacturer specifies Type B, use the appropriate Type B arrangement. A nominal 7 kW rating alone does not determine the answer.
11 or 22 kW Three-Phase AC Charger
Three-phase supply does not automatically make Type B mandatory. Check the EVSE topology and its declared DC residual-current protection. Where the possible waveform is not covered by a Type F plus RDC-DD arrangement, or Type B is specified, select Type B. Confirm pole configuration, neutral switching and overcurrent protection.
Multiple Charging Points
Individual final-circuit protection improves continuity and fault localisation. Account for accumulated normal leakage, upstream selectivity and load management. One shared RCD can cause a fault at one charger to disconnect the entire group.
DC Fast-Charging Equipment
The AC input protection of a DC charging station does not protect its DC output. Follow the charging-station manufacturer’s complete protection design. Type B selection at the AC input depends on the possible protective-conductor current and instructions; do not transfer rules from a residential Mode 3 wallbox without analysis.
RCCB or RCBO for the EV Circuit?
An РЦКБ provides residual-current protection and normally requires a coordinated MCB or fuse. An RCBO combines residual-current, overload and short-circuit protection. The residual-current type—F or B—must still suit the EVSE.
| Arrangement | Преимущество | Проверьте |
|---|---|---|
| Type F RCCB + MCB + RDC-DD | Separate devices and potentially lower RCD cost | RDC-DD compatibility, wiring, board space and coordination |
| Type F RCBO + RDC-DD | Compact individual-circuit protection | EVSE explicitly permits Type F arrangement |
| Type B RCCB + MCB | Broad residual-current capability with separate overcurrent device | Conditional short-circuit rating and backup protection |
| Тип B RCBO | Integrated circuit-level protection | Product availability, breaking capacity, poles and exact certifications |
Cost Comparison Without Misleading Fixed Prices
Type B products usually cost more than equivalent Type F products, but the total system cost can differ from the unit-price comparison. A Type F design needs a compliant RDC-DD and a reliable switching arrangement. If those functions are already inside the charger, Type F can reduce external hardware cost. If they must be added separately, the saving can shrink.
- Compare the complete installed system, not one RCD.
- Include MCB or RCBO functions, contactors, enclosure space and wiring.
- Add commissioning time for both the RCD and RDC-DD arrangement.
- Use current quotations with the same poles, ratings, certificates and Incoterms.
- Include the cost of reassessment when the EVSE is replaced.
Standards and Documents to Check
| Reference | Назначение |
|---|---|
| IEC 62955 | RDC-DDs for Mode 3 AC EV charging |
| IEC 61851-1 | General requirements for conductive EV charging systems |
| IEC 60364-7-722 / national adoption | Electrical installations supplying EVs |
| IEC/EN 62423 | Additional requirements for Type F and Type B RCDs |
| IEC/EN 61008-1 | Household and similar RCCBs |
| IEC/EN 61009-1 | Household and similar RCBOs |
Check the editions and national amendments in force for the project. A product standard confirms device requirements; it does not by itself prove that the full installation complies.
Распространенные ошибки при выборе
- Calling Type F a low-cost Type B equivalent without an RDC-DD.
- Describing Type B as a 6 mA DC detector.
- Choosing the RCD type from charger power alone.
- Assuming every commercial or three-phase charger requires Type B.
- Using Type F because Type A trips without investigating the real fault.
- Comparing an RCCB price with an RCBO price.
- Relying on an EVSE marketing page instead of the installation manual and declaration.
- Using fixed response times, frequency limits or prices for every manufacturer.
- Installing several instantaneous RCDs in series without selectivity data.
Часто задаваемые вопросы
Can Type F be used for an EV charger?
Yes, when the EVSE manufacturer and local rules permit it and suitable 6 mA DC residual-current detection is provided. Type F alone is not a universal solution for smooth DC.
Is Type B always required for EV charging?
No. Type A or Type F with an IEC 62955-compliant RDC-DD may be acceptable. Type B is used when the waveform, EVSE instructions or local rules require it.
Is Type F better than Type A for an EV charger?
Type F covers additional specified composite-frequency waveforms, but the EVSE must support that selection. Both can still require an RDC-DD for smooth DC protection.
What is the difference between RDC-DD and Type B?
An RDC-DD detects residual direct current in the EV charging system and initiates disconnection. A Type B RCD provides residual-current protection across the Type B waveform range.
Can a Type F RCD detect smooth DC?
It is not a general smooth-DC protective device. Check its specified waveforms and use a suitable RDC-DD or Type B where smooth DC protection is required.
Does a three-phase 22 kW charger need Type B?
Not solely because it is three-phase or 22 kW. Check the charger topology, built-in DC detection, manufacturer instructions and local regulations.
Should I use an RCCB or RCBO?
An RCBO integrates overcurrent protection and often improves circuit isolation. An RCCB needs a suitable MCB or fuse. Compare the complete arrangement.
How can I verify the charger has an RDC-DD?
Look for IEC 62955, RDC-DD or 6 mA DC detection in the installation manual and declaration, then confirm how the EVSE disconnects the supply.
Final Type F vs Type B Checklist
- EVSE model and charging mode confirmed
- Manufacturer RCD requirement recorded
- IEC 62955 RDC-DD documentation verified
- Residual-current waveform assessed
- Type F or Type B selected for the complete arrangement
- RCCB or RCBO overcurrent functions correctly compared
- In, IΔn, poles and breaking/conditional ratings checked
- Upstream selectivity and normal leakage assessed
- Commissioning and replacement documentation planned
For project selection, review KUANGYA’s РЦКБ и RCBO options. Request the current datasheet, declaration and certificate for the exact model. For a quotation, contact KUANGYA with the EVSE model, supply, ratings, quantity and destination.
