Guide de sélection des RCBO pour les circuits réels : Type A/AC, 30mA, courbes B/C et pôles

Une demande pour “ 32 A, 30 mA RCBO ” n'est pas prête à être commandée. Elle identifie une classe de courant de charge et un seuil de courant résiduel, mais elle n'identifie pas la forme d'onde de défaut, le courant de démarrage, la limite du câble, les conducteurs d'alimentation ou le courant de court-circuit disponible. Les deux mêmes chiffres pourraient décrire un circuit de prises général, un banc de drivers LED ou un départ d'onduleur—et ces circuits peuvent nécessiter différents RCBO.

La réponse pratique est de choisir le RCBO en fonction de la fonction de protection. Pour un circuit terminal moderne typique, le Type A et 30 mA sont souvent le point de départ. Le choix final dépend encore de si la charge produit une fuite électronique, si la courbe B peut tolérer le démarrage, quels conducteurs doivent être déconnectés et si 6 kA est suffisant au tableau.

Ce guide suit trois dossiers de projet plutôt qu'une séquence de catalogue. Chaque projet commence par un risque différent, puis se termine par une description complète du RCBO qu'un entrepreneur, un constructeur de tableaux ou un distributeur peut réellement utiliser.

Trois circuits qui ne devraient pas recevoir le même RCBO

Dossier de projet	Incertitude principale	Point de départ probable	Décision qui contrôle le résultat
Circuit de prises de bureau	Charges électroniques futures et continuité	Type A, 30 mA, RCBO individuel	Calibre du câble, niveau de défaut et interface du tableau
Éclairage LED et petit tableau de pompe	Courant de démarrage court	Type A, 30 mA, courbe B ou C	Courant d'appel mesuré/déclaré versus conditions de déclenchement en défaut
Circuit triphasé alimenté par onduleur	Forme d'onde du courant résiduel, puissance inverse et neutre	Type A/F/B défini par l'équipement et 3P/3P+N/4P	Instructions du convertisseur, topologie d'alimentation et approbation bidirectionnelle

Ces exemples sont illustratifs, et non des enregistrements de projets JUTRION achevés. Leur but est de montrer comment un paramètre change parce que le circuit change.

Dossier de projet 1 : Un circuit de prises de bureau

Le premier circuit alimente des prises générales dans un bureau 230 V. Aujourd'hui, l'équipement connecté comprend des ordinateurs portables, des moniteurs, des chargeurs et une imprimante. Demain, les occupants pourront connecter différents appareils électroniques. Le concepteur ne peut donc pas prouver que le circuit restera une simple charge AC sinusoïdale.

Le Type A est le point de départ défendable

Le Type AC répond au courant résiduel alternatif sinusoïdal. Le Type A répond également au courant résiduel DC pulsé. L'électronique monophasée moderne contient couramment des redresseurs et des alimentations à découpage, de sorte que le Type A est normalement le point de départ le plus pratique pour un circuit de prises non spécifié.

Le Type A n'est pas un substitut universel pour chaque type de RCD. Les équipements capables de produire un DC lisse ou des courants résiduels à fréquences mixtes particulières peuvent nécessiter un Type F, un Type B ou une autre disposition déclarée. Pour un circuit de prises de bureau général, cependant, le Type A répond à une population de charges plus réaliste que le Type AC.

Pourquoi 30 mA et 20 A répondent à des questions différentes

La spécification du bureau propose un calibre de courant résiduel de 30 mA pour une protection supplémentaire selon les règles d'installation applicables. Cette valeur de 30 mA est IΔn ; elle décrit la fonction de courant résiduel. Elle ne décrit pas le courant de charge que le circuit peut transporter.

Supposons que le courant de conception calculé soit de 17,2 A et que le câble installé ait une capacité de transport de courant corrigée de 24 A. Un dispositif de 20 A satisfait la relation initiale de protection des conducteurs :

Ib ≤ In ≤ Iz

17,2 A ≤ 20 A ≤ 24 A

Ici, Ib est le courant de conception, In est le courant nominal du RCBO et Iz est la capacité corrigée du câble. La température ambiante, le groupement, l'isolation, la méthode d'installation, les harmoniques et les règles nationales doivent déjà être reflétés dans Iz. Choisir 25 A parce que c'est la taille de catalogue suivante dépasserait la capacité déclarée du câble.

Les RCBO individuels protègent la continuité ainsi que les personnes

Si plusieurs circuits de bureau partagent un seul RCCB, les fuites de leurs filtres électroniques s'accumulent au niveau du dispositif partagé. Un seul événement de défaut à la terre peut également déconnecter tous les MCB en aval. Les RCBO individuels répartissent la fuite par circuit et contiennent généralement un déclenchement de courant résiduel sur la branche affectée. Cela facilite la localisation des défauts et réduit les pertes de service inutiles.

L'architecture n'élimine pas la planification des fuites. Le courant normal du conducteur de protection doit encore avoir une marge sous le seuil du dispositif, en particulier lorsque de nombreuses alimentations informatiques ou de longs câbles sont connectés.

Le résultat pour le bureau

230 V AC, RCBO 1P+N, 20 A, Type A, 30 mA, courbe B ou C sous réserve de vérification de l'appel et du défaut, pouvoir de coupure supérieur au niveau de défaut mesuré/calculé du tableau, compatible avec le jeu de barres déclaré du tableau de distribution.

La courbe et le pouvoir de coupure restent ouverts car aucun ne peut être choisi à partir des seules “ prises de bureau ”.

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Dossier de projet 2 : Éclairage LED à côté d'une petite pompe

Le deuxième tableau contient deux circuits sortants avec un courant normal similaire. L'un alimente un groupe de drivers LED ; l'autre alimente une petite pompe à démarrage direct. Les deux peuvent produire un bref pic de courant lors de la mise sous tension, mais la source et la durée de ce pic diffèrent.

Courbe B versus courbe C est une décision liée à l'appel et au chemin de défaut

Pour les caractéristiques courantes des disjoncteurs miniatures CEI, la courbe B a généralement une plage de fonctionnement instantané autour de 3–5 fois In, tandis que la courbe C est autour de 5–10 fois In. La courbe D, souvent autour de 10–20 fois In, est réservée aux applications à appel plus élevé qui ont été spécifiquement conçues. Le fonctionnement exact doit être vérifié par rapport aux données produit applicables.

Un RCBO à courbe C peut tolérer un courant de démarrage de courte durée plus important avant que son élément magnétique ne fonctionne. Cela n'en fait pas un meilleur choix polyvalent. Le seuil plus élevé signifie également que le circuit doit fournir plus de courant de défaut pour assurer une déconnexion instantanée.

Preuves issues du circuit	What it suggests	What must be verified next
Low or controlled startup peak	B curve may remain suitable	Manufacturer curve and normal switching events
Short, repeatable peak above the B magnetic region	Consider C curve	Fault-loop/disconnection conditions and cable protection
Very high transformer or motor inrush	Engineered C/D solution or different starting method	Available fault current, coordination and equipment protection
Trip occurs after running for minutes	Likely thermal overload rather than inrush	Load current, enclosure temperature, terminals and cable
Trip indication shows residual-current operation	Changing B to C will not solve it	Leakage, insulation, moisture, neutral routing and RCD type

This distinction prevents a common diagnosis error. A B-curve and C-curve RCBO with the same 30 mA marking have the same nominal residual-current sensitivity. The curve letter belongs to the overcurrent section; it does not make the RCBO more tolerant of earth leakage.

LED drivers and pump motors also change the RCD-type question

LED drivers contain electronics, so Type A is a sensible baseline. A conventional single-phase motor circuit may also include an electronic controller, soft starter or variable-speed drive. Once power electronics are introduced, the equipment instructions—not the word “motor”—determine whether Type A remains suitable or whether Type F/B behavior is needed.

The two circuit results

After verifying a modest LED-driver inrush and adequate fault current, the lighting circuit may finish as:

230 V AC, 1P+N, 16 A, Type A, 30 mA, B curve, 6 kA where the verified prospective fault current is below that rating.

If the pump starting record exceeds the B-curve region but the circuit satisfies C-curve disconnection requirements, the pump circuit may finish as:

230 V AC, 1P+N or 2P as required, 16 A, Type A (or equipment-specified type), 30 mA where required, C curve, breaking capacity matched to the board fault level.

The difference was not “lighting versus motor” by label. It was the measured or declared startup behavior, residual-current waveform and fault path.

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Project File 3: An Inverter-Backed Three-Phase Circuit

The third project connects a three-phase power-electronic system. It may import power, export power or operate differently when a backup source is active. A catalogue shortcut such as “four-pole, Type B” is unsafe because the converter design and supply topology have not yet been established.

Let the converter documentation define the residual-current type

Type F extends Type A behavior for defined mixed-frequency conditions associated with selected single-phase inverter loads. Type B covers a wider residual-current range, including smooth DC under its applicable characteristics. Some EV chargers and inverters incorporate residual direct-current monitoring; others require a particular upstream device.

The choice cannot be made from product category alone. Confirm:

• the residual-current waveform the equipment can produce;
• whether DC residual-current detection is internal;
• the exact upstream RCD/RCBO requirement in the equipment instructions;
• coordination with any upstream residual-current device;
• national rules for the application.

Do not confuse a Type B RCBO with a B-curve RCBO. Type B describes the residual-current sensing capability. B curve describes the instantaneous overcurrent response. A product can be Type B with a C curve.

Poles follow the conductors, not the load name

A three-phase, three-wire load without neutral may use a 3P arrangement. A three-phase, four-wire system with neutral requires 3P+N or 4P as defined by the product, system and installation rules. The datasheet must show whether neutral is switched, solid or protected against overcurrent.

Arrangement	Likely system	Required confirmation
1P+N	Single-phase line and neutral	Neutral switching, line/load direction and busbar position
2P	Single-phase with two-pole disconnection	Which poles are switched and overcurrent-protected
3P	Three-phase without neutral	No operating or sensing need for neutral
3P+N	Three-phase with neutral	Neutral switching/protection behavior
4P	Three-phase, four-wire with declared four-pole operation	Simultaneous operation and system compatibility

Every conductor required by the residual-current sensing arrangement must follow the manufacturer’s diagram. A borrowed or bypassed neutral creates imbalance and can make the device trip even when the loads themselves are healthy.

Reverse power requires a declared bidirectional device

Solar, batteries and vehicle-to-grid equipment can feed the circuit in the opposite direction from a conventional load. A manual toggle does not prove bidirectional suitability. Verify permitted supply direction, terminal orientation, short-circuit performance in each direction, neutral behavior and the approved board system.

The RCBO is only one part of this protection chain. It does not replace required isolation, anti-islanding functions, surge protection or safe source identification.

The inverter-circuit result

400 V AC, 3P/3P+N/4P according to the actual conductor system, residual-current type required by the converter manufacturer, sensitivity required by the application rules, C/D curve only after startup and fault verification, declared bidirectional use where power can reverse, and breaking capacity above the project fault level.

This specification is longer because the system carries more interfaces. Shortening it to “4P C32 30 mA” would discard the decisions most likely to affect compatibility.

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The Ratings Decoder: What Each Marking Proves

The three project files can now be reduced to one decoding table. Each rating closes a different risk; no single value can stand in for another.

RCBO field	Engineering meaning	Project evidence	Failure if ignored
Rated voltage/frequency	Supply conditions for declared operation	System drawings and equipment data	Incorrect operation or invalid rating
In (A)	Rated current of overcurrent section	Ib, corrected Iz and load duty	Overload trips or unprotected cable
B/C/D curve	Instantaneous magnetic response	Inrush and fault-current data	Nuisance startup trips or inadequate fault clearing
Type AC/A/F/B	Residual-current waveform capability	Load topology and manufacturer instructions	Failure to respond correctly to the possible waveform
IΔn (mA)	Residual-current sensitivity	Protection objective and installation rule	Wrong protection level or poor continuity
Poles/neutral	Conductors sensed, switched and protected	Single-line diagram and earthing system	Incorrect isolation, sensing or neutral operation
Breaking capacity (kA)	Maximum declared short-circuit interruption duty	Prospective short-circuit current	Device used beyond its tested interruption capability
Direction/board interface	Supply orientation and physical compatibility	Current datasheet and board declaration	Invalid installation, busbar mismatch or reverse-power issue

IEC 61009-1:2024 gives product requirements and tests for RCBOs for household and similar uses within its stated scope. It does not replace the national installation code. Product conformity answers whether the RCBO meets its declared product requirements; installation compliance answers whether that device is correctly applied in the circuit.

Why 10, 30, 100 and 300 mA Are Not Quality Grades

A lower IΔn is more sensitive, but “more sensitive” does not mean “better for every position.” Ten milliampere devices may be selected for particular local or higher-sensitivity duties. Thirty milliamperes is widely used for additional protection on final circuits. One hundred and 300 mA values can serve selected upstream, equipment or fire-risk roles.

An upstream 100 or 300 mA device does not replace downstream 30 mA protection where 30 mA is required. Conversely, installing instantaneous 30 mA protection at both upstream and downstream levels can undermine selectivity because both devices see the same earth-fault imbalance.

Where upstream residual-current protection is used, coordinate both threshold and operating time. A selective/time-delayed function belongs at the level allowed by the installation design; it must not delay a final-circuit protective function that is required to operate promptly.

6 kA or 10 kA Is a Location Decision

Breaking capacity must be at least the prospective short-circuit current at the RCBO’s installation point under its declared conditions. A board near a transformer can have a higher fault level than a distant final circuit, even when the distant building is physically larger.

Use a calculation, measurement or reliable project fault-level record. If upstream backup protection is proposed, use a tested or declared manufacturer combination. An upstream breaker with a large interruption rating does not automatically transfer that rating to a downstream RCBO.

Backup protection and selectivity are also different. A combination may interrupt a high fault safely while both devices open. If continuity requires only the downstream circuit to disconnect, obtain selectivity evidence for the relevant current range.

Turn Project Data into an Orderable Description

Before selecting a model, assemble one short project record:

• country/market and applicable installation requirements;
• system voltage, frequency and earthing arrangement;
• single-phase or three-phase conductors, including neutral;
• load description, electronic converter topology and startup current;
• design current and corrected cable capacity;
• required residual-current protection objective;
• prospective short-circuit current at the board;
• power-flow direction in every operating mode;
• consumer-unit/distribution-board model, busbar and available module width;
• terminal, environmental, indication and accessory requirements.

Then write the specification in one line:

[voltage/frequency], [poles and neutral arrangement], [In], [curve], [Type AC/A/F/B], [IΔn], [breaking capacity], [supply direction], [product standard/market approval], [board and busbar interface].

This line is more useful than asking a supplier for “a good RCBO.” It gives engineering and purchasing teams the same reference and exposes missing information before samples or production are committed.

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Validate the Selected RCBO in the Actual Board

A technically correct rating set can still fail at the assembly interface. Before a distributor accepts a replacement range or an OEM releases a consumer unit, the selected RCBO should be checked in the intended enclosure with the intended busbar, conductors and accessories.

Mechanical and wiring fit

Confirm module width, DIN-rail engagement, busbar tooth position, neutral location and terminal access. A device described as 1P+N may use a flying neutral lead, a neutral terminal on a particular side or a different busbar pitch from another 1P+N device. Similar front dimensions do not prove interchangeability.

Check the permitted conductor material, rigid/flexible cross-section and ferrule requirements. Prepare conductors as declared and apply the specified terminal torque. A loose connection can create heat without exceeding the circuit load current, while excessive torque can damage the terminal or conductor.

Functional evidence

Commissioning should distinguish the two trip systems. Where the device provides separate indication, record whether a test operation is reported as residual-current or overcurrent. Verify the test-button function under the supply conditions stated by the manufacturer, then complete the installation tests required by the applicable rules. The test button checks an internal functional path; it does not measure the complete earth-fault loop, insulation condition or every trip-time requirement.

For circuits with many electronic loads, record normal load current, startup peak and standing leakage after commissioning. Those three values create a baseline. If trips appear months later, maintenance can compare new evidence with the original condition rather than replacing devices by trial and error.

Temperature and grouping

Several loaded modular devices mounted side by side can operate in a warmer local environment than the room temperature suggests. Enclosure ventilation, adjacent heat-producing components, conductor size and sustained loading all affect temperature. Apply the manufacturer’s derating or spacing instructions where relevant; do not respond to a thermal trip by increasing the ampere rating without rechecking cable protection.

Batch and documentation control

For an OEM or distributor, lock the approved attributes into the bill of materials: exact model, curve, residual-current type, IΔn, poles, breaking capacity, terminal arrangement, approval and compatible accessories. A substitute that matches only current and width can silently change the waveform type or neutral behavior.

Retain the current datasheet, declaration/certification documents required by the target market, wiring diagram and lot identification with the approved sample record. This turns selection into a repeatable production control rather than a one-time engineering conversation.

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Separate Product Compliance from Installation Compliance

An IEC marking is important, but it does not decide where or how the RCBO may be installed. IEC 61009-1:2024 defines general requirements and tests for RCBOs for household and similar uses within its stated scope. National wiring rules, local regulation, project specifications and the authority having jurisdiction determine the installation application.

Question	Where the answer comes from	Example
Was the RCBO evaluated as a product?	Product standard, certification and manufacturer documentation	Declared voltage, current, IΔn, type and short-circuit capacity
Is residual-current protection required here?	National installation rules and project design	Socket, outdoor, wet-location or special-equipment circuit
Which residual-current type is permitted?	Installation rules plus equipment instructions	Restriction on Type AC or requirement created by converter equipment
Will the circuit disconnect in time?	Installation calculation/test and device characteristic	Fault-loop conditions for a chosen B/C/D curve
Can the RCBO fit this board?	Board-system and device-manufacturer declarations	Busbar, terminals, neutral position and enclosure rating

This distinction matters in export projects. A product configuration accepted in one market may require a different residual-current type, pole arrangement, approval mark or distribution-board system in another. Do not convert a national rule into a universal IEC claim, and do not assume that a component certificate approves the completed panel.

La BEAMA RCD selection guide is a useful authoritative source for waveform and application reasoning, particularly around modern electronic loads. Its regional installation references still need to be applied within their own jurisdiction. For another market, use the relevant national rules and equipment instructions.

Where an RCBO Fits—and Where It Does Not

An RCBO combines residual-current protection with overload and short-circuit protection. An RCCB normally requires coordinated overcurrent protection, while an MCB does not provide residual-current protection. The RCBO-per-circuit architecture often improves continuity and fault isolation, but it must still coordinate with upstream protection and the distribution board.

An RCBO does not normally recognize hazardous arc signatures. If arc-fault mitigation is part of the project, use the JUTRION AFDD guide to map the required protection functions. RCBOs also do not replace SPDs, isolators or equipment-specific protection simply because several functions share one enclosure.

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Choose the Protection Job Before the Catalogue Number

The office circuit began with unpredictable electronic loads, so Type A and individual 30 mA protection controlled the decision. The lighting and pump circuits began with startup behavior, so the B/C curve choice depended on both inrush and fault current. The inverter circuit began with waveform, conductor topology and reverse power, so equipment instructions and bidirectional approval mattered before amperage.

That is the transferable selection rule: identify the fault the RCBO must detect, prove the cable and fault path, then complete the physical interface. A correct catalogue number is the output of that process, not the starting point.

JUTRION offers RCBOs for single-phase and three-phase distribution with multiple pole, current, sensitivity, waveform-type, curve and breaking-capacity combinations. Share the project record above when requesting selection support so the proposed model can be checked against the real circuit.

Questions fréquemment posées

Technical References

• IEC 61009-1:2024 — RCBO general rules and scope
• BEAMA Guide to the Selection and Application of Residual Current Devices