{"id":3295,"date":"2026-09-24T01:00:00","date_gmt":"2026-09-24T01:00:00","guid":{"rendered":"https:\/\/cnsuton.com\/?p=3295"},"modified":"2026-09-22T08:21:32","modified_gmt":"2026-09-22T08:21:32","slug":"sensibilidade-do-disjuntor-diferencial-30ma-100ma-300ma","status":"publish","type":"post","link":"https:\/\/cnsuton.com\/pt\/blog\/rccb-sensitivity-30ma-100ma-300ma\/","title":{"rendered":"Como escolher a sensibilidade do disjuntor diferencial (RCCB): 30 mA, 100 mA ou 300 mA"},"content":{"rendered":"

RCCB sensitivity selection<\/strong> starts with the hazard and protection objective, not with a memorized mA value. A 30 mA setting is commonly reviewed for additional protection against electric shock, while 100 mA or 300 mA settings may be used for equipment, fire-risk or upstream coordination duties where the adopted rules permit. The correct value depends on earthing arrangement, touch-voltage risk, normal leakage, connected equipment, required disconnection time, selectivity and the exact RCCB. Never choose a higher threshold simply to stop nuisance tripping without investigating leakage and the protection study. Write the intended protection objective in the schedule, identify the responsible approving engineer, and keep the selected threshold tied to the exact model and installation mode.<\/p>\n

Define what the residual-current device must protect<\/h2>\n

Write whether the device is intended for additional protection of people, protection against insulation-fault or fire risk, feeder backup, or coordination with downstream RCCBs. These objectives can require different sensitivity and time behavior. A 30 mA device can respond to small residual current but may be affected by the normal leakage of filters, drives, power supplies and long cables. A 100 mA or 300 mA device may provide upstream equipment protection, but it is not a substitute for a downstream additional-protection device where the rules require one.<\/p>\n

\n\n\n\n\n\n\n\n\n
Nominal sensitivity<\/th>\nTypical design question<\/th>\nEvidence required<\/th>\n<\/tr>\n
30 mA<\/td>\nIs additional protection required for the final circuit or user-accessible equipment?<\/td>\nAdopted installation rules, device type, disconnection time and leakage study<\/td>\n<\/tr>\n
100 mA<\/td>\nIs an upstream equipment or feeder threshold permitted and coordinated?<\/td>\nProtection study, measured leakage and manufacturer curve<\/td>\n<\/tr>\n
300 mA<\/td>\nIs the objective feeder or fire-risk protection rather than personal additional protection?<\/td>\nRisk assessment, local rules and time-delay\/selectivity evidence<\/td>\n<\/tr>\n
Any setting<\/td>\nCan normal leakage stay below the operating threshold with margin?<\/td>\nMeasured or calculated leakage by operating mode<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
\"Actual
Sensitivity must match the protection objective and installation design.<\/figcaption><\/figure>\n

The values are planning examples, not a universal selection rule. The adopted code and manufacturer instructions control.<\/small><\/p>\n

Use leakage and disconnection evidence<\/h2>\n

Estimate or measure normal residual current with all expected loads operating, including filters, variable-speed drives, LED supplies, heating elements and long cable runs. Include startup, standby, transfer and generator modes. A device selected just below the normal leakage can nuisance-trip, while a device selected too high can delay fault clearing beyond the permitted limit.<\/p>\n

Schneider Electric’s RCCB sensitivity guidance<\/a> explains why the choice is tied to the application and protection objective. Use it as a terminology reference, not as a substitute for the SUTON manual or local adoption. State the actual current path, neutral arrangement and required test method in the approval record.<\/p>\n

Check type, waveform and time delay<\/h2>\n

Sensitivity is only one setting. Confirm the RCCB type and waveform response required by the connected loads, the rated residual operating current, non-operating current, time delay and test-button behavior. Electronic loads can produce residual waveforms that are not represented by a simple sinusoidal assumption. Check whether the device supports the required AC, pulsating DC or other response defined by the project and manufacturer.<\/p>\n

Time delay can help upstream\/downstream coordination, but it changes the protection sequence. Do not add delay to solve nuisance trips without checking the required disconnection time and touch-voltage limits. The RCCB selectivity guide<\/a> covers the coordination question, while the two-pole versus four-pole RCCB guide<\/a> covers the conductor arrangement.<\/p>\n

Confirm installation and testing<\/h2>\n

Verify line and load terminals, neutral routing, protective-earth separation, test-button wiring, enclosure conditions and the manufacturer’s torque instructions. The test button confirms a defined internal test circuit; it does not replace the project acceptance test. Record the device code, threshold, delay, test instrument, measured result and as-left state.<\/p>\n

IEC 60947-2:2024<\/a> provides product-standard context for low-voltage circuit breakers, while HSE electrical-safety guidance<\/a> reinforces competent work and safe isolation. Apply the project edition and local rules.<\/p>\n

Selection workflow<\/h2>\n
    \n
  1. State the protection objective.<\/li>\n
  2. Identify earthing, neutral and source arrangements.<\/li>\n
  3. Calculate or measure normal leakage in every operating mode.<\/li>\n
  4. Select RCCB type, sensitivity and delay from the adopted rules and manufacturer data.<\/li>\n
  5. Check disconnection time, selectivity, breaking capacity and conductor protection.<\/li>\n
  6. Record model code, settings, test method and commissioning result.<\/li>\n<\/ol>\n

    Use the SUTON ETM1L product page<\/a> as a product starting point. Request exact sensitivity, delay and waveform data before quotation approval.<\/p>\n

    The circuit-breaker types guide<\/a> is the parent overview for comparing RCCB selection with other low-voltage protection decisions.<\/p>\n

    When several feeders share a panel, compare their leakage and fault behavior instead of assigning every circuit the same nominal threshold. A documented exception is safer than an unexplained setting copied from a neighboring feeder. Recheck the decision after a load, cable or source change, and keep the result with the commissioning record before handover and future maintenance by the owner and engineer with sign-off for traceability and audit later securely for reference when needed by all parties for safety and clarity.<\/p>\n

    Build an approval record that can be audited<\/h2>\n

    Record the exact catalog code, frame, rated current, poles, voltage, residual-current function, settings, terminals, accessories, mounting arrangement and document revision. Keep the as-designed, as-installed and as-left information separate. A family brochure is not enough when several sensitivities, pole arrangements or trip units share an enclosure.<\/p>\n

    The technical file should include the single-line diagram, fault-current study, protection study, conductor schedule, panel drawing, manufacturer instructions and commissioning results. If a value comes from a calculation, state the source inputs and revision. If it comes from a manufacturer table, identify the exact table and device combination.<\/p>\n

    Commissioning and safe-work boundary<\/h2>\n

    Before energization, verify device identity, settings, pole arrangement, conductor placement, terminal preparation, tightening method, barriers, labels, handle operation, auxiliary functions and mechanical interlocks. Testing and fault studies must be carried out or approved by qualified people under the adopted rules. This article supports specification work and does not authorize energized work.<\/p>\n

    After a serious fault or unexplained trip, do not simply reset the device. Investigate the cause, inspect the RCCB and connected equipment as required by the manufacturer, and confirm that settings remain correct.<\/p>\n

    Information to include in an RFQ<\/h2>\n

    Give bidders the system voltage and frequency, AC or DC duty, poles and neutral arrangement, normal current, calculated maximum and minimum fault current, residual-current sensitivity and time delay, required breaking capacity, conductor and terminal details, accessories, control voltage, mounting, ambient conditions and required documents. Ask for a completed compliance schedule rather than an unqualified family datasheet.<\/p>\n

    Require the offered model to be decoded in full. Options such as electronic residual-current modules, test buttons, auxiliary contacts, shunt trips and time delays can change the product code and wiring. An accessory shown in a brochure photograph is not automatically part of the quotation.<\/p>\n

    Close the evidence loop before purchase approval<\/h2>\n

    Place each supplier answer beside the project requirement and classify it as compliant, conditional or noncompliant. Do not treat a blank cell as compliance. Resolve alternative offers with the same technical review applied to the base offer, and retain the approved schedule with the purchase order. Confirm that the datasheet revision, drawing, setting sheet and installation instructions all describe the same catalog code and option package.<\/p>\n

    Ask who owns the protection calculation, who sets the device, and which operating modes were included. Record assumptions that still depend on vendor data. This discipline prevents a late discovery about neutral sensing, pole arrangement, leakage, delay or an accessory from becoming a panel change after shipment.<\/p>\n

    At handover, keep the final model code, settings, test results, marked-up single-line diagram and commissioning record together. Future maintenance staff should be able to see exactly which conductors, sources and residual-current functions were included in the decision. If a later replacement uses a different trip technology or accessory, repeat the review instead of assuming the original coordination still applies.<\/p>\n

    Where the quotation offers alternatives, ask the supplier to identify every changed interface and every changed assumption. A different pole arrangement, sensitivity selector, delay module or terminal kit can alter the panel drawing, coordination study and test plan even when the front label appears similar.<\/p>\n

    Do not close the review with a generic statement that the device is \u201csuitable.\u201d State the intended protection objective, the selected value, the evidence source, the operating modes covered and the limitation that remains. That record makes later troubleshooting and replacement safer.<\/p>\n

    \"Actual
    The front label does not by itself define a universal mA selection.<\/figcaption><\/figure>\n
    \"Actual
    Time delay, sensitivity and selectivity are separate checks.<\/figcaption><\/figure>\n

    Related SUTON technical resources<\/h2>\n

    Use the linked product and related guides as procurement starting points, then verify the offered device against the project study. Similar-looking RCCBs can have different ratings, terminals, trip functions and approvals.<\/p>\n

    Educational video<\/h2>\n

    The following neutral educational video supports the electrical principle discussed here. It does not replace project calculations or manufacturer instructions.<\/p>\n