What Is Dielectric Strength — IEC 60335?
The dielectric strength test is a test in which a defined voltage is applied to an insulating material or the device's insulation barrier, checking whether breakdown or excessive leakage current occurs. It is also known as the hipot test in product safety standards.
Purpose of Dielectric Strength — IEC 60335
The purpose is to verify the adequacy of the insulation that protects the user from electric shock under normal and fault conditions.
Which Products Is Dielectric Strength — IEC 60335 Applied To?
- Household and similar electrical appliances
- Information-technology and audio/video equipment
- Laboratory and measuring instruments
- Power supplies and adapters
- Insulation materials and sheets
In Which Sectors Is Dielectric Strength — IEC 60335 Used?
Standards Related to Dielectric Strength — 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
Dielectric Strength — IEC 60335 Conditions
- Voltage type
- AC (50/60 Hz) or DC; determined by the product standard
- Voltage level
- Defined in the product standard according to the insulation class and working voltage
- Application time
- Generally 60 s in a type test; a shorter time and elevated voltage may be used in a production-line test
- Environment
- May be required to be applied after humidity conditioning
Equipment for Dielectric Strength — IEC 60335
- High-voltage test set (hipot tester)
- Leakage-current measurement rig
- Humidity conditioning chamber
- Safety cage and interlock
Sample Requirements for Dielectric Strength — IEC 60335
- The specimen may be the complete product or the relevant insulation component
- The humidity conditioning required by the product standard is applied before the test
- Connection points and grounding arrangement are set up per the standard
Duration of Dielectric Strength — IEC 60335
A single application is generally 60 seconds. Total duration can reach several hours depending on conditioning and the number of measurement points.
Dielectric Strength — IEC 60335 Procedure
- 1Test points and voltage level are determined per the product standard.
- 2The specimen is subjected to humidity conditioning if required.
- 3Voltage is raised from zero to the target value in a controlled manner.
- 4Voltage is maintained for the defined duration; breakdown or excessive leakage current is monitored.
- 5Voltage is reduced in a controlled manner and the specimen is discharged.
Dielectric Strength — IEC 60335 Acceptance Criteria
There must be no breakdown or surface flashover during the test, and leakage current must not exceed the product standard's limit. Limit values are given in the product standard according to the device's insulation class and working voltage.
Evaluation of Results
Breakdown, arcing, or leakage current above the standard's limit is considered non-conformity. The type-test result and the production-line routine test are evaluated separately.
Dielectric Strength — IEC 60335 Report
- Applied standard and revision
- Test points and insulation class
- Voltage type, level and duration
- Measured leakage-current values
- Conditioning conditions
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 authorisationsRelated Regulations
- LVD 2014/35/EU
- Product safety regulations
Electrical Safety — What Does This Testing Field Cover?
The section below describes the field that the Dielectric Strength 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 Dielectric Strength — IEC 60335
Are the hipot test and dielectric strength the same thing?
In practice they refer to the same test. Hipot is the common name for the process of applying high voltage; dielectric strength is the measured property of the material or barrier.
Who determines the test voltage?
The product standard determines it. Different voltage levels are defined for the same device's basic insulation, reinforced insulation, and functional insulation.