នៅលើទំព័រនេះ
Choosing a Residual Current Circuit Breaker (RCCB) requires more than selecting 40A or 63A, and more than choosing 30 mA. Those markings describe different characteristics. A complete RCCB specification must define:
- the protection architecture: RCCB with a separate MCB or fuse, or an RCBO instead;
- វាយតម្លៃបច្ចុប្បន្ន ក្នុង;
- ចរន្តប្រតិបត្តិការសេសសល់ដែលបានកំណត់ (Rated residual operating current) IΔn;
- residual-current type: AC, A, F, or B;
- pole arrangement;
- វ៉ុល និងប្រេកង់ដែលបានកំណត់ (Rated voltage and frequency);
- instantaneous or selective/time-delayed operation; and
- documented coordination with the associated overcurrent protective device.
Start with the circuit and the required protection function. Finish with a written specification that can be checked against the exact datasheet, coordination table, certificate, and installation rules. Do not start with whichever RCCB model is available on the shelf.
RCCB Selection Worksheet: Inputs to Specification
Use this table before comparing products. A blank input means the RCCB is not ready to specify.
| ទិន្នន័យបញ្ចូលដែលត្រូវការ | Selection decision | Specification output | ភស្តុតាងសម្រាប់ផ្ទៀងផ្ទាត់ |
|---|---|---|---|
| Required protection architecture | RCCB plus MCB/fuse, or RCBO | Device family and protection arrangement | Circuit design, panel architecture, applicable rules |
| Supply system and live conductors | Voltage, frequency, and poles | Ue, frequency, 2P/4P or other verified arrangement | Single-line diagram, equipment diagram, product instructions |
| Design current and duty | Required current-carrying rating | ក្នុង | Load schedule, diversity assessment, ambient and grouping conditions |
| Protection objective and installation position | ភាពប្រែប្រួលចរន្តលេច | IΔn | Installation rules, earthing design, circuit function |
| Connected equipment and possible residual-current waveform | ប្រភេទ RCCB | Type AC, A, F, or B | Equipment manual, load topology, applicable rules |
| Upstream/downstream residual protection | Time characteristic and selectivity | Instantaneous or selective/time-delayed | Manufacturer selectivity data and protection study |
| Prospective fault conditions and associated MCB/fuse | ការសម្របសម្រួលពេលមានការឆ្លងចរន្តខ្លី (Short-circuit) | Required backup SCPD and conditional rating evidence | Exact RCCB–MCB/fuse coordination table |
| Destination market and project documents | Standard and approval pathway | Applicable standard edition, certificates, reports | Exact model documents, not a family-level assumption |
The output is not a model number yet. It is a requirement against which model numbers can be screened.
Step 1: Confirm That an RCCB Is the Correct Device
An RCCB detects residual current but does not include integral overload or short-circuit protection. IEC 61008-1:2024 covers RCCBs without integral overcurrent protection for household and similar uses within its stated voltage, frequency, and current scope.
That functional boundary changes the first selection decision:
| Required architecture | Device to evaluate | Key implication |
|---|---|---|
| Residual-current protection with a separate MCB or fuse | RCCB | The RCCB and associated overcurrent protective device must be coordinated as a combination |
| Residual-current, overload, and short-circuit protection in one device | RCBO | The device must satisfy both residual-current and overcurrent requirements |
| One RCCB protecting a group of MCB-fed circuits | RCCB + MCBs | Consider cumulative leakage and the extent of supply loss if the RCCB operates |
| Independent protection and fault isolation for each outgoing circuit | Individual RCBOs may be more suitable | Each circuit needs its own complete residual-current and overcurrent specification |
For the panel-level tradeoff, use the VIOX guide to RCBO versus RCCB plus MCB. If the design requires an RCCB, continue with the remaining fields below.
Step 2: Specify Voltage, Frequency, and Poles
Record the actual supply arrangement rather than treating pole count as a cosmetic choice.
Match the rated voltage and frequency
The RCCB’s declared operating voltage and frequency must cover the circuit conditions. Check the exact datasheet, including whether the test circuit and any voltage-dependent functions have supply requirements. Do not infer suitability from the current rating or physical module width.
Match the pole arrangement to the live conductors
All live conductors belonging to the protected circuit and required by the device design must pass through the RCCB’s residual-current sensing arrangement. A common preliminary mapping is:
| Supply arrangement | ចំណុចចាប់ផ្តើមទូទៅ | What still requires verification |
|---|---|---|
| Single-phase line and neutral | RCCB 2 ប៉ូល | Neutral arrangement, terminal identification, switching requirements, rated voltage |
| បីដំណាក់កាលជាមួយអព្យាក្រឹត | RCCB 4 ប៉ូល | Phase sequence where relevant, neutral treatment, equipment diagram, rated voltage |
| Three-phase without neutral | Product- and system-dependent | Whether the selected RCCB design supports the arrangement and how every live conductor is monitored |
This table is a selection aid, not a wiring instruction. Installation must follow the exact device diagram and applicable rules. The separate 2-pole and 4-pole RCCB wiring guide covers the installation task after the product has been selected.
Step 3: Determine Rated Current In
The ampere marking on an RCCB is its rated current ក្នុង: the current it is designed to carry under its declared conditions. It is not an overload trip setting.
A 63A RCCB does not wait for 63A and then trip like an overcurrent protective device. The associated MCB, fuse, or other protective device must provide the required overload and short-circuit protection.
Use four checks when specifying In:
- Design current: Determine the current the RCCB is expected to carry from the circuit schedule and diversity assessment.
- Installation conditions: Check manufacturer instructions for ambient temperature, grouping, enclosure conditions, and other factors that can affect current-carrying suitability.
- Associated overcurrent protection: Confirm that the selected MCB or fuse rating and characteristic protect the RCCB within the manufacturer’s declared coordination conditions.
- Conductor protection: Verify cable protection separately. Increasing the RCCB from 40A to 63A does not increase cable ampacity and does not cure residual-current tripping.
Write the selection requirement as a coordinated statement, not a standalone number:
Rated current In: ___ A, suitable for the calculated duty and verified with the specified upstream or associated ___ A MCB/fuse under the manufacturer’s declared conditions.
Step 4: Select Rated Residual Operating Current IΔn
IΔn is the residual-current sensitivity, normally expressed in milliamperes. It answers a different question from In.
| សញ្ញាសម្គាល់ | អ្វីដែលវាពិពណ៌នា | ឧទាហរណ៍ធម្មតា |
|---|---|---|
| ក្នុង | Current-carrying rating | 25A, 40A, 63A, 100A |
| IΔn | ចរន្តប្រតិបត្តិការសេសសល់ដែលបានកំណត់ (Rated residual operating current) | 30mA, 100mA, 300mA |
Select IΔn from the required protection objective, circuit position, earthing arrangement, normal leakage, disconnection requirements, and applicable local rules. In many IEC-based installations, a device not exceeding 30mA is associated with additional protection for specified circuits. Higher values may serve fault-protection, upstream, selective, or fire-risk functions where the design and applicable rules permit.
Do not use a higher IΔn simply to hide unwanted tripping, and do not assign one value to an entire building category. For the full decision process, use the dedicated 30mA versus 100mA versus 300mA RCCB sensitivity guide.
Record the result as one specification field:
Rated residual operating current IΔn: ___ mA, selected for the documented protection objective and installation position.
Step 5: Select Type AC, A, F, or B
RCCB type describes the residual-current waveforms the device is designed to detect. It does not describe the MCB trip curve, and it cannot be selected from the premises label alone.
Begin with the connected equipment:
- Does it contain rectifiers, electronic power supplies, inverters, drives, or DC links?
- What residual-current waveform can it produce under normal and fault conditions?
- Does the equipment manufacturer specify an upstream RCD type or a separate DC detection arrangement?
- Do applicable installation rules restrict Type AC or require a particular capability?
Use this boundary map for preliminary screening:
| ប្រភេទ RCCB | Preliminary waveform boundary | ការប្រុងប្រយ័ត្នក្នុងការជ្រើសរើស |
|---|---|---|
| វាយ AC | ចរន្តលេចធ្លាយឆ្លាស់រលកស៊ីនុស | Do not use merely because it is the lowest-cost option; verify that the load and rules permit it |
| ប្រភេទ A | AC plus pulsating DC residual currents within the applicable product definition | May still be unsuitable where smooth DC or other complex residual currents can occur |
| ប្រភេទ F | Additional capability for specified composite residual currents associated with certain single-phase frequency-converter loads | Not a universal substitute for Type B |
| ប្រភេទ ខ | Includes capability for smooth DC and additional frequency components within the applicable product definition | Do not treat it as a universal upgrade; equipment instructions, system coordination, national rules, and any separate DC detection arrangement still control the final choice |
IEC 62423 specifies additional requirements and tests for Type F and Type B RCDs and is used together with the relevant RCCB or RCBO product standard. The exact model documentation must identify the type and applicable standard pathway.
Record the evidence, not only the letter:
Residual-current type: Type ___, based on the connected-equipment manual, expected residual-current waveform, and applicable installation requirements.
Step 6: Choose the Time Characteristic
If one residual-current protective device is installed upstream of another, different IΔn values alone do not prove selectivity. The upstream and downstream devices must be coordinated by both residual-current threshold and operating-time behavior, supported by manufacturer data and the installation design.
Specify whether the device is:
- instantaneous, where the required protection function calls for prompt operation; or
- selective/time-delayed, where an upstream device is intended to coordinate with downstream protection and the application permits that delay.
A selective device must not be substituted for a required fast additional-protection function merely to improve continuity. Record the time characteristic and the coordination evidence together:
Time characteristic: ___; coordination to be verified against upstream/downstream device references ___ and manufacturer selectivity data ___ .
Step 7: Verify Short-Circuit and Overcurrent Coordination
This step is what turns a list of RCCB ratings into a defensible specification.
Because an RCCB has no integral overcurrent protection, its behavior under short-circuit conditions depends on the declared arrangement with an associated or backup short-circuit protective device. Product documentation may state a conditional short-circuit current and identify the required fuse, MCB, or other SCPD.
Before accepting a model, verify:
- the prospective short-circuit current at the installation point;
- the exact RCCB reference, not only the product family;
- the exact associated MCB or fuse type and rating;
- the manufacturer’s conditional short-circuit or backup-protection table;
- any maximum upstream protective-device rating;
- overload coordination and conductor protection;
- upstream/downstream residual-current selectivity where applicable; and
- rated voltage, frequency, poles, and terminal arrangement for the same model.
Do not assume that a prominent short-circuit value on a brochure means the RCCB independently interrupts that current. Read what the value represents and what backup device is required.
For the boundary between product requirements and installation design, see the VIOX explanation of តម្រូវការស្តង់ដារ IEC 61008-1 សម្រាប់ឧបករណ៍ RCCB. IEC 61008-1:2024 provides general rules; the applicable IEC 61008 Part 2 depends on the RCCB classification and design.
Worked Example: From Circuit Inputs to an RCCB Requirement
The following example is hypothetical. It demonstrates documentation logic, not a universal product recommendation.
Recorded project inputs
- 230V, 50Hz single-phase circuit with line and neutral;
- calculated design current: 32A;
- separate 32A MCB retained for overcurrent protection;
- applicable installation design requires 30mA additional protection;
- connected-equipment documentation requires Type A residual-current protection;
- no upstream residual-current device requiring time discrimination;
- prospective short-circuit current has been calculated but must be checked against the exact RCCB–MCB combination; and
- destination-market documents and certificates must be supplied for the exact model.
Resulting preliminary specification
| វិស័យ | Hypothetical output |
|---|---|
| ស្ថាបត្យកម្ម | RCCB with separate 32A MCB |
| បង្គោល | 2P, subject to the product wiring diagram and neutral requirements |
| Rated voltage/frequency | Suitable for 230V, 50Hz circuit conditions |
| ក្នុង | 40A minimum in this example, subject to manufacturer confirmation with the exact 32A MCB and installation conditions |
| IΔn | 30 mA |
| ប្រភេទ | ប្រភេទ A |
| លក្ខណៈពេលវេលា | ភ្លាមៗ |
| Short-circuit evidence | Manufacturer table confirming the exact RCCB + 32A MCB combination for the calculated prospective current |
| ឯកសារ | Datasheet, applicable certificate/report, wiring diagram, coordination data, and model identification |
Changing any major input can change the result. A three-phase load changes the pole and voltage review. Power-electronic equipment can change the required RCCB type. An upstream residual-current device introduces a selectivity study. A different prospective fault current can invalidate the proposed backup combination.
Final RCCB Specification Template
Complete this block before requesting a product match or quotation:
Project / circuit reference:
Destination market:
Protected load and circuit position:
Protection architecture: RCCB + [MCB / fuse / other SCPD]
Rated current In: ___ A
Rated residual operating current IΔn: ___ mA
Residual-current type: AC / A / F / B / other verified type
Poles: ___
Rated voltage: ___ V AC
Rated frequency: ___ Hz
Time characteristic: instantaneous / selective / other verified class
Associated overcurrent protective device:
Manufacturer / series / reference: ___
Rating and characteristic: ___
Prospective short-circuit current at installation point: ___
Required conditional short-circuit / backup evidence: ___
Required upstream/downstream selectivity evidence: ___
Applicable product standard and edition: ___
Applicable installation rules: ___
Connected-equipment instruction reference: ___
Required certificates, reports, and drawings: ___
Quantity and delivery/documentation requirements: ___Only after completing these fields should the project team compare the available ជួរផលិតផល VIOX RCCB. Blank cells in a product summary are not proof that a rating is available or unavailable; open the exact model documentation or request confirmation.
Datasheet and RFQ Verification Checklist
Before approving the selected RCCB, confirm that all of the following refer to the same exact model:
For a model review, send the completed specification, single-line diagram, destination market, quantity, and required documentation to [email protected]. VIOX can then identify the closest published RCCB series for verification without substituting a generic ampere or milliampere value for the project design.
Focused Selection Questions
Can a 63A 30mA RCCB replace a 40A 30mA RCCB?
Not from those two markings alone. Both devices may share the same IΔn, but the replacement must also match the voltage, frequency, poles, RCCB type, time characteristic, terminal arrangement, product standard, and documented coordination with the associated overcurrent protective device.
Does 30mA mean the RCCB is rated for a 30A load?
No. 30mA normally identifies IΔn, the rated residual operating current. Load-carrying capacity is identified separately by In, such as 40A or 63A.
Should the RCCB current rating be higher than the MCB rating?
Do not apply a standalone rule without the product documents. The RCCB must carry the design duty and be protected by the associated overcurrent device within the manufacturer’s declared coordination conditions. Verify the exact RCCB–MCB or RCCB–fuse combination.
Is a 4-pole RCCB always used for every three-phase circuit?
Four-pole RCCBs are a common starting point for three-phase systems with neutral, but the final arrangement depends on the circuit conductors, neutral requirements, device design, supply system, and applicable rules. Verify the exact diagram instead of selecting poles from the phrase “three phase” alone.
