Insulation Resistance – IEC 60335 / IEC 62368 / IEC 61010

What Is Insulation Resistance — IEC 60335?

The insulation resistance test is a test in which resistance is calculated from the current flowing when a defined DC voltage is applied to the insulation barrier. It reveals insulation degradation caused by moisture, contamination and ageing.

Purpose of Insulation Resistance — IEC 60335

The purpose is to verify that the insulation retains adequate resistance even under moisture and contamination.

Which Products Is Insulation Resistance — IEC 60335 Applied To?

Electrical appliances and panels
Motors and windings
Cables and connectors
Battery packs
Machinery electrical installation

In Which Sectors Is Insulation Resistance — IEC 60335 Used?

ElectricalElectronicsMachineryMedical Device

Standards Related to Insulation Resistance — IEC 60335

IEC 60335Safety in home and similar electrical devices test
IEC 62368Security in audio, video and information technology devices test
IEC 61010Safety in measuring, control and laboratory devices test

Insulation Resistance — IEC 60335 Conditions

Test voltage: Defined in the product standard; a common value is 500 V DC
Measurement duration: Until the value stabilises; typically 60 s
Measurement points: Between live parts and accessible metal parts
Pre-conditioning: Some standards require measurement after humidity conditioning

Equipment for Insulation Resistance — IEC 60335

Insulation resistance tester (megohmmeter)
Humidity conditioning chamber
Test connection rig
Discharge rig

Sample Requirements for Insulation Resistance — IEC 60335

Measurement points must be determined
The insulation class must be documented
The timing of measurement after conditioning must be recorded
Capacitive components must be discharged

Duration of Insulation Resistance — IEC 60335

The measurement is short; conditioning determines the total duration.

Insulation Resistance — IEC 60335 Procedure

1Measurement points and the test voltage are determined.
2Humidity conditioning is applied if required.
3DC voltage is applied and held until the value stabilises.
4Resistance is read and recorded.
5The specimen is discharged safely.

Insulation Resistance — IEC 60335 Acceptance Criteria

The acceptance criterion is given in the product standard as a minimum resistance value (e.g. a lower limit on the order of MΩ for basic insulation).

Evaluation of Results

The measurement is affected by temperature and humidity; conditions are stated in the report. A delay in measurement after conditioning changes the result.

Insulation Resistance — IEC 60335 Report

Standard applied
Test voltage and measurement points
Ambient temperature and humidity
Measured resistance values
Conditioning information

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

LVD 2014/35/EU
Machinery Directive
UNECE R100 (EV)

Electrical Safety — What Does This Testing Field Cover?

The section below describes the field that the Insulation Resistance test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Electrical safety testing shows that a device poses no risk of electric shock, fire or injury to the user in normal use and under foreseeable fault conditions. This family is the test group most often requested when a product enters the market; almost every electrically operated product passes through this gate.

The logic of the field rests on a single assumption: FAULTS WILL HAPPEN. Insulation will age, a component will short, a cable will break, the user will misuse the device. Standards therefore test not only normal operation but also single fault conditions. The sentence "the device works correctly" is not evidence in this field; the evidence is that the device stays safe when it fails.

Assessment addresses three layers together. In the constructional layer, insulation distances (creepage and clearance), protective barriers, earthing continuity, enclosure strength and component selection are examined — this layer is largely a matter of inspection and measurement rather than testing. In the electrical layer, dielectric strength, leakage current, insulation resistance and behaviour under fault conditions are measured. In the thermal layer, temperature rise in normal and abnormal operation is monitored; an overheating component is both a fire risk and a risk of insulation breakdown.

Which standard applies is determined by WHAT THE PRODUCT IS, and that decision affects the entire outcome. Household appliances fall under the IEC 60335 series, information technology and audio/video products under IEC 62368-1, measurement and laboratory equipment under IEC 61010-1, and medical devices under IEC 60601-1. A report obtained under the wrong standard is not accepted in the file even if the measurements it contains are correct.

Component conformity is often overlooked in this field. The safety of the device rests on the conformity of the transformer, optocoupler, fuse, switch and power supply it uses. The list of critical components and the certification status of each is part of the technical file; a change of component reopens the safety assessment.

Method groups in this field

Constructional examination
Insulation distances, barriers, earthing arrangement, accessibility and selection of critical components are examined. It comes before testing and many non-conformities are caught here.
Dielectric strength
It is verified that the insulation withstands the defined voltage. It must not be confused with the routine test on the production line; the type test is more severe.
Leakage current and earthing
The current that could reach the user is measured; the continuity and resistance of the protective earthing path are verified.
Heating tests
Temperatures of components, windings and accessible surfaces are measured in normal and abnormal operation.
Fault condition tests
Components are deliberately short-circuited or open-circuited; the appliance is expected not to cause a fire and not to make a hazardous part accessible.
Mechanical and enclosure tests
Impact, drop, strain relief, IP protection and the safety of moving parts are assessed.

Commonly confused in this field

A CB certificate is not a CE declaration. CB is the output of a mutual recognition arrangement that eases national certification; the CE declaration is made by the manufacturer under its own responsibility.
A part of IEC 60335 is not sufficient on its own; it is applied together with Part 1.
IEC 60950-1 and IEC 60065 have been withdrawn. Old certificates based on these codes cannot be used in a current file.
Separate certification of the adapter does not cover the conformity of the device; the device is assessed as the system it forms together with its power supply.
A change of critical component (transformer, fuse, optocoupler supplier) is not a silent change; it requires the safety file to be reviewed.

Which decisions these results support

CE declaration under the Low Voltage Directive
IECEE CB certificate and entry into national certification schemes
Assessing the safety impact of design changes
Establishing and maintaining the critical component list
Responding to market surveillance requests

Related Tests

Frequently Asked Questions About Insulation Resistance — IEC 60335

According to which standard is Insulation Resistance made?

Insulation Resistance is executed in scope IEC 60335-1, IEC 61010-1, IEC 60204-1, IEC 60364-6, UNECE R100, IEC 60335, IEC 62368 and IEC 61010. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.

Which products does Insulation Resistance apply to?

Mainly applied to Electrical appliances and panels, Motors and windings, Cables and connectors, Battery packs and Machinery electrical installation. Whether your product is included in the scope is determined by examining its technical specifications and intended use.

Under what conditions is Insulation Resistance done?

The determining parameters are: Test voltage — Defined in the product standard; a common value is 500 V DC, Measurement duration — Until the value stabilises; typically 60 s and Measurement points — Between live parts and accessible metal parts. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.

What kind of sample is needed for Insulation Resistance?

Measurement points must be determined, The insulation class must be documented and The timing of measurement after conditioning must be recorded. The number of samples is determined according to the product standard and the scope to be reported.

How long does Insulation Resistance take?

The measurement is short; conditioning determines the total duration. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.

What is the Insulation Resistance result called "appropriate"?

The acceptance criterion is given in the product standard as a minimum resistance value (e.g. a lower limit on the order of MΩ for basic insulation).