A leakage current test report is a formal document that records the measured leakage and touch-current values of electrical and electronic products, verifying compliance with safety standards such as IEC 60335, IEC 62368-1, and IEC 60601-1. This guide explains how such reports are structured, which types of leakage current are tested, the measurement methodology defined in IEC 60990, typical acceptance limits, and how manufacturers use these reports for certification and quality control.
Technical Overview
Leakage current is the unintended electrical current that flows across insulation, or through filtering components such as Y-capacitors, from live parts to accessible surfaces or to the protective earth conductor. Although small in magnitude, excessive leakage current can cause perceptible tingling, involuntary muscle reaction, or electric shock, and it is therefore one of the core electric safety parameters evaluated in virtually every product safety standard.
A leakage current test report issued by an accredited third-party laboratory provides objective evidence that a product meets the leakage current limits of its applicable standard. The report is commonly required for market access schemes such as the CB Scheme, CE marking, CCC certification, UL listing, and for demonstrating due diligence during design verification or production quality control.
A complete leakage current test report typically contains the following elements:
- Product identification, including model designation, ratings, and classification (Class I, Class II, Class III, or applied-part type for medical devices)
- The applicable standards and specific clauses against which the evaluation was performed
- Test conditions, including supply voltage, frequency, ambient temperature, and relative humidity
- Instrumentation details, including the leakage current tester and its calibration status
- Measured values at each measurement point under both normal and single fault conditions
- A clear pass or fail judgment against the limit values, together with measurement uncertainty where applicable
Testing Samples
Household and Similar Electrical Appliances
Refrigerators, washing machines, air conditioners, microwave ovens, kettles, fans, and similar appliances are evaluated under the IEC 60335 series or its Chinese national equivalent GB 4706.1. Limits depend on the appliance class and whether the appliance is portable or stationary.
IT, Audio/Video, and Communication Equipment
Computers, monitors, routers, power adapters, televisions, and amplifiers are evaluated under IEC 62368-1, the hazard-based standard that replaced IEC 60950-1 and IEC 60065, and the corresponding GB 4943 series. Touch current is measured using the methodology of IEC 60990.
Medical Electrical Equipment
Medical devices carry the strictest leakage current requirements because current may flow through the patient. IEC 60601-1 and GB 9706.1 define earth leakage current, enclosure leakage current, and patient leakage current for B, BF, and CF type applied parts, with limits that can be as low as 10 microamperes under normal conditions.
Luminaires and Lighting Control Gear
LED drivers, ballasts, and luminaires are tested under IEC 60598-1 and GB 7000.1, particularly for touch current at accessible metal or conductive parts in both normal and fault conditions.
Power Tools, Transformers, and Power Supplies
Hand-held tools, transformers, and switch-mode power supplies
These products are evaluated under standards such as IEC 62841, IEC 61558, and their national adoptions, where leakage current limits are tied to the insulation class and earthing arrangement of the product.
Testing Items
Depending on the product standard, one or more of the following quantities appear on the measurement sheet of a leakage current test report:
Protective Conductor Current
- The current flowing in the protective earth conductor of Class I equipment under normal operating conditions, measured with all protective conductors intact.
Touch Current
- The current that would flow through a person bridging accessible parts and earth, measured using the human body impedance simulation network of IEC 60990 with the protective conductor interrupted to simulate the worst case.
Earth Leakage Current
- The total leakage from all live parts to earth, relevant for medical equipment and for verifying that residual current devices will not nuisance-trip.
Enclosure Leakage Current
- The current flowing from accessible non-earthed parts of the enclosure to earth, applicable mainly to medical electrical equipment.
Patient Leakage and Patient Auxiliary Current
- Currents flowing through the patient via applied parts or between applied parts, unique to medical devices and categorized by the applied part type (B, BF, or CF).
Leakage Under Single Fault Conditions
- Measurements repeated with one protective measure defeated at a time, such as an open neutral conductor or an interrupted protective earth, with correspondingly relaxed or specific limits.
Testing Methods
Measurement Network and Instrumentation
Leakage and touch current are not measured with a simple ammeter. IEC 60990 specifies a measurement network that simulates the impedance of the human body, together with a frequency-weighting circuit that accounts for the increased physiological effect of current at higher frequencies. The indicating instrument responds to true RMS values, and the complete measurement chain must be calibrated and traceable.
Test Conditions and Supply Voltage
Tests are performed with the sample supplied at 1.06 times rated voltage for household appliances and IT equipment, or 1.10 times rated voltage for medical equipment, at the rated frequency. Samples are typically tested after humidity conditioning and at operating temperature, as specified by the relevant product standard, because moisture and thermal stress increase leakage. Laboratory ambient conditions are documented in the report.
Measurement Procedure
The measurement circuit is connected between accessible parts and the reference earth of the supply, with the measurement network inserted in the circuit. Measurements are taken for both polarity positions of the supply plug, for each accessible part, and with switch positions set to the worst-case configuration. The highest recorded value is compared against the limit in the product standard.
Single Fault Condition Simulation
For touch current, the protective conductor is opened to create the single fault condition, and measurements are repeated. For some standards, interruption of the neutral conductor or reversal of the supply polarity is also simulated. Typical acceptance limits referenced in reports include 0.25 mA for Class II appliances, 0.75 mA for portable Class I appliances, 3.5 mA for stationary Class I equipment under IEC 60335-1 and IEC 62368-1, and 10 to 100 microampere levels for medical devices under IEC 60601-1, always as specified by the applicable standard.
Applications
Leakage current test reports are used throughout the product lifecycle and across the supply chain:
- Certification and market access: supporting CB Scheme certificates, CE declarations of conformity, CCC certification, and UL or EN standard compliance dossiers.
- Design verification: confirming that insulation systems, Y-capacitor selection, and filtering design keep leakage within limits before tooling investment.
- Production quality control: earth leakage testing is a standard routine test on production lines, and periodic re-testing validates manufacturing consistency.
- Component and supplier qualification: evaluating power supplies and modules before integration into end products.
- Failure analysis and complaint investigation: diagnosing reported tingling sensations, nuisance tripping of RCDs, or non-compliance found during market surveillance.
FAQ
What is the acceptable leakage current limit for my product?
There is no universal limit. It depends on the product standard, the class of construction, and whether the value is measured under normal or single fault conditions. Typical values are 0.25 mA for Class II products, 0.75 to 3.5 mA for Class I equipment, and single- or double-digit microampere values for medical devices. The report must always cite the specific clause and limit of the applicable standard.
How is leakage current testing different from an insulation resistance or electric strength test?
Insulation resistance and dielectric strength tests apply a stressed voltage to the insulation to detect defects, whereas leakage current testing measures the actual current that would reach a user or the protective earth under normal supply voltage. The tests are complementary and are usually performed together in a full safety evaluation.
Is the test destructive to the sample?
No. Leakage current measurement is a non-destructive test performed at slightly elevated supply voltage. The sample remains functional afterward, although humidity conditioning performed before measurement may require a drying period.
How long is a leakage current test report valid?
Laboratories generally state validity in terms of one year from the test date for commercial purposes, but the technically correct answer is that the report reflects the specific sample, design revision, and standards edition tested. Any design change, standard update, or major component substitution warrants re-testing.
What should be done if a measured value exceeds the limit?
Exceedance usually indicates excessive Y-capacitance, degraded or contaminated insulation, inadequate creepage and clearance, or an earthing defect. Engineers should review the EMI filter design and insulation coordination, implement corrective actions, and submit a revised sample for confirmation testing before resuming the certification process.