EN
Residual Current Device Test Inspection
Testing of RCDs in electrical panels: tripping current verification, tripping time measurement and continuity checks with authorised engineers, signed reports.
Residual current device test measures, with a test instrument under real leakage current, the tripping accuracy, tripping time and detection function of the RCD/RCB/RCM devices protecting human life directly in electrical panels. Because the relay senses touch current and cuts the circuit in a tiny slice of a second, it is an invisible lifesaver; a drifted, mechanically stuck or earth-reference-broken RCD is the most misleading source of false comfort in the panel.
Test and Control Items
- Differential current tripping: Raising the leakage to verify the nominal differential current (IΔn: e.g. 30 mA, 300 mA) for AC and, on type A/AC-A/F/B devices, pulsating and smooth DC scenarios; checking the non-trip at 50% IΔn and guaranteed trip at IΔn rule.
- Tripping time: Measuring total disconnection time at nominal and double fault current; verifying the touch-voltage protection link (energisation time limit) in TN systems.
- Leakage line continuity: Continuity of the PE conductor and earth reference at the relay output; test button function (the button checks circuit continuity, not the threshold — mechanical movement audited).
- Panel integrity: Connection tightness, thermal traces, dust-moisture marks, labelling and selectivity (zone cascade) arrangement; switch type-data compatibility.
- Selectivity: Verification of coordination between the general 300 mA and downstream 30 mA devices; preventing unnecessary panel blackout in a fault scenario.
Legislation and Standards
Under the Regulation on Internal Electrical Installations and periodic control legislation, residual current devices must be tested at least once a year; practice is expected to be tightened for wet areas, construction sites, agricultural facilities and public spaces. Technical references: device performance TS EN 61008 / TS EN 61009 series, selection and installation rules TS HD 60364 (especially the 701 series for wet rooms), instrument requirements TS EN 61557-6. Results and device serial numbers are reported as accreditation and audit evidence.
Risks and Operator Recommendations
The common field non-compliance is accepting an RCD because its test button "trips": the button verifies circuit continuity, not the opening threshold. Using 300 mA instead of 30 mA in wet areas keeps the touch current in the fatal band. Unauthorized copy substitutions must be rejected on type mismatch. Test results must be trended, and circuits showing persistent leakage rise must be investigated for insulation weakness (an installation fault, not a relay defect). Monthly checklists are recommended for portable site boards and extension cords.
Outcome
At the end of testing, a signed report with the relay-based threshold-time table is issued. RCD tests are within our Periodic Inspection of Installations group. See the complementary Electrical Installation Earthing Inspection and contact us for panel inventories.
FAQ on Residual Current Device Testing
The residual current device (RCD/ELCB) detects the phase-neutral current imbalance (earth leakage) and cuts the circuit within milliseconds as a life-safety element: it stops touch voltage before it turns dangerous on an insulation fault. Relays can degrade or go blind through mechanical-chemical ageing, dust-humidity, voltage oscillation and being untested; therefore the trip value and time must be measured periodically by injection and the monthly test button discipline must be run.
With an RCD injection kit: trip current per type AC-A-B-FIV (typically 30 mA for life, 300 mA for fire, with stage coordination), trip time (ms, standard limit by type-class), leakage measurement with touch voltage (leak clamp-shunt-oscilloscope), response to positive-negative-alternating-sinusoidal-noise (frequency); connection tightness-earthing continuity, relay mechanical energy-manual test, selectivity-short-circuit coordination (type-S delayed stage) and synchronised verification with the previous-next panel. Results are reported with a limit table.
Monthly with the operator test button; engineering measurement-injection as periodic control — usually yearly in practice, shortened toward six months in welding-humid-heavy-industry-hygienic environments. Reporting is mandatory within the Internal Electrical and Earthing Regulations; TS HD 60364 installation rules and the product standards (IEC 61008/61009, types AC-A-F) set the thresholds. Critical circuits (medical-water pump-heater-kitchen-energy) get monitoring priority; a failed device is replaced immediately and logged.
Trip current above limit (a 30 mA device not tripping beyond 35 mA) or delayed trip time, dead test button or unlocked mechanism, dusty-humid-burn-trace relay, corroded-hot connection (thermal) and broken selectivity (the upper relay opening before the lower one, repeated nuisance cuts): these show the device cannot be trusted. The report tags urgency with a replacement suggestion (type-current-selectivity redesign) and recommends panel maintenance-cleaning-torque with the monthly test card discipline.