What is IEC 61010?
IEC 61010 is the international series of standards setting safety requirements for electrical measurement, test, control and laboratory equipment, protecting users and the surroundings against electric shock, fire, burns, mechanical hazards and other risks that originate from the equipment itself. The series consists of a general part, IEC 61010-1, and a large number of supplementary parts for specific products, from multimeters and current clamps to centrifuges and PLCs. In OT environments, IEC 61010 touches almost everything that measures and controls: transmitters, signal converters, process controllers, HMIs with measurement functions, calibrators and the control equipment inside the control cabinet.
🧠 What exactly does IEC 61010 cover?
IEC 61010 is a product safety standard. It describes how a manufacturer must design and test its equipment so that it stays safe in normal use and under a single fault. The standard is maintained by technical committee IEC TC 66 and has the status of a group safety publication, which means other product standards refer to it.
The main hazards IEC 61010-1 protects against:
- Electric shock - accessible parts must not become hazardous live, which is achieved through insulation, clearances and creepage distances, and a protective earth connection.
- Fire - limiting the spread of fire inside and outside the enclosure.
- Excessive temperature - accessible surfaces and components must not get too hot.
- Mechanical hazards - moving parts, sharp edges, stability and the strength of the enclosure against impact or dropping.
- Radiation, toxic substances and implosion - including lasers, UV radiation and released gases.
- Hazards from faults - the equipment must remain safe under a single fault as well (for example a short-circuited component or a disconnected earth conductor). Continued operation is not required, failing safely is.
Since the third edition (2010), Part 1 also contains a separate clause on risk assessment (Clause 17) for hazards the standard does not address explicitly. What IEC 61010 explicitly does not cover is performance, accuracy, EMC (covered by IEC 61326-1), functional safety and explosion protection.
📦 Which parts make up the IEC 61010 series?
The current version of Part 1 is edition 3.1 from 2017: the third edition of 2010 combined with Amendment 1 of 2016 in a single document. As of October 2026 a fourth edition had not been published; recent Part 2 standards still refer to this version. The supplementary parts (2-xxx) modify or extend Part 1 and are always used together with it.
| Part | Subject | Example equipment |
|---|---|---|
| IEC 61010-1 | General requirements | Any measurement, control or laboratory equipment |
| IEC 61010-2-030 | Equipment with testing or measuring circuits | Power analysers, data loggers, measurement cards |
| IEC 61010-2-032 | Hand-held current sensors | Current clamps |
| IEC 61010-2-033 | Hand-held multimeters | Multimeters for mains voltage |
| IEC 61010-2-034 | Insulation resistance meters | Megohmmeters |
| IEC 61010-031 | Probe assemblies | Test leads, probes |
| IEC 61010-2-010 / 2-020 | Heating of materials, centrifuges | Ovens, laboratory centrifuges |
| IEC 61010-2-201 | Control equipment | PLCs, I/O modules, operator panels |
For the OT world, IEC 61010-2-201 is the most important part. It was first published in 2013 and took over the product safety clauses (11 to 14) of IEC 61131-2, the standard for programmable controllers. Since then, IEC 61131-2 covers the functional, EMC and environmental requirements of a PLC, while IEC 61010-2-201 covers electrical safety. The current, third edition was published in October 2024 and added, among other things, insulation requirements for SELV and PELV circuits.
⚡ What are measurement categories (CAT II, III and IV)?
A widely used concept from IEC 61010 is the measurement category. It indicates at which point of a low-voltage installation a measuring circuit may safely measure, and therefore which voltage spikes (transients) its insulation must withstand. Since the third edition, the measurement categories are no longer in Part 1 but in IEC 61010-2-030.
| Category | Measuring point in the installation | Example in a plant |
|---|---|---|
| O (formerly CAT I) | Circuits not directly connected to the mains | 24 V DC sensor supply, 4-20 mA loop, electronics behind a power supply |
| CAT II | Circuits connected to a final circuit through a plug | Socket outlets, portable tools, laboratory equipment |
| CAT III | The fixed installation of the building | Distribution boards, control cabinets, permanently connected motors |
| CAT IV | The source of the installation | Service entrance, utility meter, overhead lines |
A multimeter rated “CAT III 1000 V” may therefore be used in a distribution board up to 1000 V, but not at the service entrance. The higher the category, the larger the transient the instrument has been tested against.
Note the difference with overvoltage categories (IEC 60664-1). Those concern the mains supply of the equipment itself, not what it measures. A PLC or process controller with a 230 V supply must meet the overvoltage category of the point where it is connected. The measuring inputs of a 24 V sensor or transmitter do not need a CAT rating.
🔁 How does IEC 61010 relate to other standards and legislation?
In the EU, the European version EN 61010-1 is harmonised under the Low Voltage Directive 2014/35/EU. That directive applies to equipment between 50 and 1000 V AC and between 75 and 1500 V DC. Compliance with the harmonised standard gives a presumption of conformity and supports the CE marking. In North America, the nearly identical UL 61010-1 and CSA C22.2 No. 61010-1 apply, and the IECEE CB Scheme allows one test report to be reused internationally.
| Standard | Scope | Relation to IEC 61010 |
|---|---|---|
| IEC 60204-1 | Electrical equipment of machines | Applies to the machine; built-in measurement and control equipment complies with IEC 61010 itself |
| IEC 61439 | Switchgear and controlgear assemblies | Covers the cabinet; IEC 61010 covers the instruments and controllers inside it |
| IEC 61131 | Programmable controllers | Function and EMC; safety through IEC 61010-2-201 |
| ISO 13849-1 and IEC 61508 | Functional safety | Complementary: IEC 61010 concerns the equipment itself, not safety functions |
| IEC 60079 | Explosive atmospheres | Outside the scope of IEC 61010; ATEX zones have separate requirements |
| NEN 1010 | Low-voltage installations in the Netherlands | Installation standard, not a product standard; the location in the installation determines which measurement category an instrument needs |
| NEN 3140 | Operation of electrical installations | Governs safe working practices, including the use of suitable measuring equipment |
Cybersecurity is also outside the scope of IEC 61010. The digital security of a PLC or networked measuring instrument is addressed by IEC 62443 and, for new products placed on the EU market, the Cyber Resilience Act.
🏭 How do you apply IEC 61010 in practice?
For an end user, OEM or panel builder, IEC 61010 mainly matters when selecting, installing and using equipment. A practical approach:
- Check conformity - when purchasing, ask for the EU declaration of conformity listing EN 61010-1 and the relevant Part 2, or for a CB test report.
- Respect the operating conditions - by default, Part 1 assumes indoor use, altitudes up to 2000 m, 5 to 40 °C, a maximum relative humidity of 80 % up to 31 °C (decreasing linearly to 50 % at 40 °C), mains voltage fluctuations up to ±10 %, transient overvoltages up to overvoltage category II and pollution degree 2. If you install outside those limits, for example in an outdoor enclosure or a damp room, you need equipment explicitly specified for it.
- Choose the right measurement category - instruments used for fault-finding in a distribution board must be rated at least CAT III for the voltage present there. The same applies to the test leads under IEC 61010-031: the lowest category in the chain determines the safety.
- Follow the installation instructions - connecting the protective earth, fitting the specified fuse and covering terminals are often conditions of the type test.
- Manage measuring equipment - include safety checks of test leads and instruments in the calibration process and the NEN 3140 inspections.
Common mistakes include using a multimeter rated only CAT II in a distribution board, continuing to use damaged test leads, operating equipment outside its specified environmental conditions and disconnecting the earth to “solve” a measurement problem.
❓ Frequently asked questions
Is IEC 61010 mandatory?
IEC 61010 is not legally mandatory as a standard, but in the EU EN 61010-1 is harmonised under the Low Voltage Directive. Manufacturers who comply with it obtain a presumption of conformity for the CE marking. In practice, IEC 61010 is therefore the standard route for measurement, control and laboratory equipment.
What is the difference between IEC 61010 and IEC 62368-1?
IEC 61010 applies to measurement, control and laboratory equipment, whereas IEC 62368-1 is the safety standard for audio, video and ICT equipment. An industrial PC usually falls under IEC 62368-1, a process controller or PLC under IEC 61010. When in doubt, the intended use of the equipment determines which standard applies.
What does CAT III on a multimeter mean?
CAT III on a multimeter means that, under IEC 61010, the instrument is safe for measurements in the fixed installation of a building, such as distribution boards and permanently connected machines. The number that follows, for example 600 V or 1000 V, is the maximum voltage to earth. Measurements at the service entrance require CAT IV.
Does a PLC fall under IEC 61010?
Yes, the electrical safety of a PLC and other control equipment has been covered by IEC 61010-2-201 since 2013. That part took over the product safety requirements from IEC 61131-2, which since its 2017 edition only contains functional, EMC and environmental requirements. A PLC manufacturer therefore tests its product against both standards.
Does IEC 61010 cover functional safety?
IEC 61010 does not cover functional safety. The standard ensures that the equipment itself does not create a hazard, while standards such as IEC 61508, IEC 62061 and ISO 13849-1 set requirements for safety functions that protect a process or machine. A safety PLC must therefore meet both kinds of standard.
Which version of IEC 61010-1 is current?
The current version of IEC 61010-1 is edition 3.1 from 2017, the third edition of 2010 combined with Amendment 1 of 2016. In the EU, the European version EN 61010-1 with its amendment applies. Manufacturers must check with every new edition whether their product still complies.
📌 In summary
IEC 61010 is the product safety standard for electrical measurement, control and laboratory equipment, from multimeter to PLC. Part 1 contains the general requirements, supplementary parts cover specific products and measurement categories, and in the EU EN 61010-1 gives a presumption of conformity under the Low Voltage Directive. In OT environments the standard helps you select safe instruments and controllers, but functional safety, explosion protection and cybersecurity call for other standards.