IEC TC 31 committee and its work

Standardisation work of the IEC TC 31

The IEC's standardisation work is organised across 150 Technical Committees (TC) and Subcommittees (SC) with various areas of focus. The topics are prepared within committees in Working Groups (WG), Adhoc Groups (AHG), Project Teams (PT) and Maintenance Teams (MT). The team is permanently tasked with creating, checking and revising international standards. These working groups are monitored and coordinated by the Plenary Group. This is responsible for implementing the work programmes of the relevant TCs and their SCs efficiently on time. The members of the TCs are countries which are represented by named persons.

One of these Technical Committees is the IEC TC 31 (TC 31), which deals with equipment for explosive atmospheres, operator tasks and area classifications, amongst other topics. The IEC TC 31 is tasked with establishing and updating the IEC standard series IEC 60079 (electrical explosion protection) and IEC 80079 (non-electrical explosion protection) so that these can be applied at the IEC level in the IECEx system for the conformity assessment. Alongside the ATEX directives, which are binding throughout the EU, the IEC standards set the most important principles for manufacturers of electrical and non-electrical equipment destined for use in hazardous areas and the essential requirements for operators of systems installed in these areas.

The aim of the TC 31 is to establish uniform standards applicable worldwide (uniform technical requirements) in the field of explosion protection in order to reduce the effort spent on certification and use the same products globally.

Within Europe, the effort spent on certification has already been significantly reduced through harmonisation by means of the binding ATEX directives. This is because in Europe every ATEX certificate must be recognised by a notified body. A manufacturer therefore only needs to have one certificate in order to bring to the market their explosion-protected equipment within the European Economic Area. Before this harmonisation was introduced, a manufacturer still had to produce a separate national certificate for each country.

In addition, parallel voting already exists in Europe which means that IEC standards are largely fully adopted into European standards. IEC standards are already fully adopted in national standards in some other countries too. Thus one IECEx certificate is currently sufficient for the international sale of explosion-protected equipment in the regions of Australia, New Zealand, Singapore and Israel. No further national certificate is required. In Europe, only an additional ATEX label and the resulting ATEX certificate is required. In the USA and other regions, the IEC standards are applied with some deviations.

At present, 40 countries from all over the world are members of the TC 31, which is involved in the implementation and recognition of international standards.

Below is an overview of the current trends in international standards in explosion protection:

November 2022IEC TC 31 MeetingsSan Francisco, USAStandard Information November 2022
09.05. - 18.08.2022IEC TC 31 MeetingsHybrid Meeting LondonLatest standard August 2022
06.10.2020IEC standards conference TC 31Online MeetingLatest standard December 2021
04.11. - 06.11.2020IEC standards conference TC 31Online MeetingLatest standard November 2020
26.10. - 06.11.2020IEC standards conference TC 31Northbrook, USACancelled due to the Coronavirus
20.04. - 01.05.2020IEC standards conference TC 31Northbrook, USACancelled due to the Coronavirus
25.03. - 05.04.2019IEC standards conference TC 31Waldenburg, GermanyLatest standard May 2019
21.10. - 01.11.2019IEC standards conference TC 31Nanyang, ChinaLatest standard November 2019







Relation IEC - EU - DPDF (71 KB)
Relation of the standard groupsPDF (95 KB)
Relation of working groupsPDF (81 KB)

IEC – Organisational structure

The International Electrotechnical Commission (IEC) is the world's leading organisation for international standards in the fields of electrotechnology and electronics.

The IEC's work is based on three pillars – standardisation work, market and technology development and conformity assessment.
These are organised as follows:

Ex IEC organisational structure R. STAHL
Source: IEC

At the IEC level, international standards in electrotechnology are established by Technical Committees (TC), Subcommittees (SC) and various Working Groups (WG). In total, over 20,000 IEC experts all over the world are actively involved in this process. The committees are managed by the Standardization Management Board (SMB). Superordinate topic areas, such as energy efficiency, environmental aspects or information security and data protection, are dealt with in Technical Advisory Committees, Strategic Groups and Systems Work.

The Market Strategy Board (MSB) has the task of identifying the most important technological trends and market requirements in the IEC's areas of activity and of determining the priorities for the technical work and the conformity assessment. It can set up special Working Groups in order to investigate certain topics in detail.

The Conformity Assessment Board (CAB) coordinates and monitors the work of the four IEC conformity assessment systems, IECEE, IECEx, IECQ and IECRE, and develops new activities as required, such as at present for the topic of cyber security.

Organisation of the IEC TC 31

In addition to the 13 Working Groups (WG), 3 Project Teams (PT), 12 Maintenance Teams (MT), 3 Joint Working Groups (JWG), and 1 Adhoc Group (AHG), the IEC TC 31 is divided into 3 Subcommittees (SC) with a similar organisational structure as the superordinate TC 31:

  • SC 31G               Intrinsically-safe apparatus
  • SC 31J                Classification of hazardous areas and installation requirements
  • SC 31M               Non-electrical equipment and protective systems for explosive atmospheres
Ex organisation IEC TC 31 committee R. STAHL

While the Project Teams and Maintenance Teams have a vertical structure, i.e. each one deals with creating and/or updating just one standard, Working Groups, Adhoc Groups and Joint Working Groups have a horizontal organisation, i.e. their work covers multiple standards. This means that one Working Group is involved in establishing and updating several or all IEC standards. Adhoc Groups are only set up for certain special topics and are often either disbanded after a few meetings or converted into a Working Group.
Joint Working Groups generally work with members of other TCs.

The designation PT and MT is therefore used according to the standard they are dealing with. By contrast, WG, AHG and JWG are numbered consecutively.


Relation IEC - EU - DPDF (71 KB)
Relation of the standard groupsPDF (95 KB)
Relation of working groupsPDF (81 KB)

Creating and further developing a standard

Before a standard can be adopted as a new standard, it is normally preceded by a Technical Specification (TS). This is initiated by a National Committee (NC) submitting what is known as a New Work Item Proposal (NWIP) to the Chair's Advisory Group (CAG) or at the TC 31 Plenary Meeting. A Project Team is then put together which continues the work by drafting a corresponding TS. The NWIP then goes through the following draft steps until it can be adopted as a TS.

Before the work can begin, a survey is started amongst the National Committees. To do this, a Document for Comments (DC) is prepared which is distributed for discussion. A document with the status Committee Draft (CD) is then compiled which contains the technical comments. This takes place in at least one voting session.

In the next step, a first vote is held on the draft with the status Committee Draft for Voting (CDV), whereby the National Committees can introduce editorial changes.

Then the final vote on the draft takes place with the status Final Draft International Standard (FDIS). The National Committees then vote for or against the new draft.

The final decision on the publication of the TS is made at the annual Plenary Meeting.

Ex creating technical specification R. STAHL

After publication, the Technical Specification initially has a validity (stability) of three years. At the end of this period, there are three options for further development: On expiry of the validity period, the TS can be incorporated into a new standard. The Project Team is then organised into a Maintenance Team, which is responsible for updating the standard from then on. If the TS proves not to be required within these three years, it will be disbanded. In another case, it is also possible that the TS will be continued unchanged.

Existing standards are valid for five years after publication. Within this period, around two to three years before the end of the validity period, work starts on updating the standard. The document then goes through another revision process, starting with a survey amongst the National Committees (DC status), a draft publication (CD status), draft for voting (CDV status), final draft (FDIS status) and, finally, approval by the TC 31 Plenary Meeting.

Ex lifecycle of IEC standard R. STAHL

How the IEC TC 31 works

At the TC 31 level, there are two meetings a year. The first meeting is held in March/April. This is the meeting of the Chair's Advisory Group (CAG), which formulates the recommendations which are then later presented as a decision template in the Plenary Meeting. Participation in the CAG meeting is restricted to the Convenors and Secretaries of the TC 31 and the relevant Subcommittees (SC), Project Teams (PT), Maintenance Teams (MT), Working Groups (WG), Adhoc Groups (AHG) and Joint Working Groups (JWG).

The second meeting, the Plenary Meeting, takes place in September/October. All member countries are represented here. Every country has an official representative with one vote each in any relevant votes. In addition to the official representatives, members of the CAG are also present at this meeting so that they can provide reports at the Plenary Meeting. The relevant active Working Groups meet in parallel to these meetings.

Involvement of R. STAHL in IEC TC 31

For a long time now, R. STAHL has been participating in many different national and international committees and panels focused on achieving the IEC's objective of establishing explosion protection standards that can be used as a worldwide benchmark. R. STAHL draws on an exceptionally rich variety of experience in the development and production of innovative, explosion-protected products.
R. STAHL puts this expertise to good use to ensure that, from a technical perspective, new and existing regulations and standards can always be implemented effectively in practice; it also strives to ensure that test procedures are rigorous, safe, and as efficient as possible.

Eight of our experts are currently involved in various Working Groups that deal with amendments to the applicable explosion protection standards. Furthermore, our company is represented by three Convenors in the Chair's Advisory Group and three in the TC 31 Plenary Meeting.