CE-labelled electrical and non-electrical equipment is safe when operated within a normal environment. Of course, in the UK UKCA marking will apply from 1st January 2021, with a transition period lasting till January 1st 2022. However, certain modern industrial environments pose an increased risk of fire and explosion, due to the use of flammable gases, vapours or combustible dusts.
These potentially hazardous environments, also known as “Ex areas” (short for explosive areas), are found in a range of industries, including oil and gas refineries, distribution facilities, pharmaceutical manufacturers, chemical processing plants, grain and agricultural handling (including distilleries), processing and storage facilities and underground mines.
Equipment used in these hazardous environments must therefore be expressly designed to minimise such risks, and equipment and system (both electrical and non-electrical) manufacturers must ensure that products meet the enhanced requirements of applicable regulations and standards which are set out currently by the UK government and the European Union (EU).
Within the EU, compliance with the ATEX Directive (2014/34/EU) is required. Some areas outside of the EU also accept the ATEX directive, such as the Middle East. Other global markets such as North America require HazLoc and China have the CCC certification scheme. For outside Europe, there is the IECEx Equipment and Personnel Certification Scheme.
Although similar in scope and intent, the ATEX Directive and the IECEx Scheme have different requirements and assessment approaches, complicating the regulatory approval process.
Increasingly, electrical and electronic equipment is being used in potentially hazardous environments to automate or control certain production processes. However, its use in close proximity to flammable or combustible gases or materials increases the risk of fire or explosion, as the normal operation of electrical and non-electrical equipment often involves actions or reactions that are a potential ignition source, such as:
- Electric sparks – A poor quality component or electrical connection can fail, inadvertently producing an electric spark that can ignite gases or nearby materials.
- High operating temperature – Depending upon the particular potentially explosive atmosphere content, hot surfaces on equipment could cause auto ignition. Process system heating effects by ‘work done’ i.e. pumping systems, must also be considered as these can elevate the ‘product’ above its flashpoint.
- Electrostatic discharge – Some normal equipment operations can generate static electricity, which can serve as an ignition source at certain levels.
- Friction sparks – Equipment operation may also involve repeated contact between materials, resulting in friction that can produce heated sparks.
To be able to eliminate potential ignition sources, including considered faults, prior to manufacture and installation, a pre-assessment is required to understand the equipment design and operation and desired location and environment. This can be carried out for existing non-electrical equipment which was manufactured and installed prior to July 2003.
The ATEX Directive
The ATEX Directive provides a detailed overview of the essential health and safety requirements applicable to equipment used in hazardous environments, including protective systems, components and safety devices. The ATEX Directive requirements are mandatory throughout the European Economic Area (EEA), which comprises EU member nations as well as Iceland, Norway, Switzerland and Liechtenstein.
Like all EU Directives, the ATEX Directive generally relies on the application of relevant standards to assess technical compliance. Compliance with the technical requirements of EU harmonised standards provides a presumption of conformity with the Directive’s essential requirements.
In cases where relevant harmonised standards do not exist, manufacturers are required to apply other EU standards, or applicable national or international standards. In rare cases, where a particular product is not covered by any existing standard, a manufacturer is required to complete a thorough evaluation of the product to demonstrate compliance.
Under the provisions of the ATEX Directive, evidence of compliance is generally demonstrated by the issuance of a manufacturer’s, or supplier’s, Declaration of Conformity, based on an independent technical assessment. Special requirements apply to electrical products intended for use in high risk areas. The task of demonstrating compliance with the ATEX Directive rests with the party responsible for introducing a product into the EU marketplace. This is typically the product manufacturer, but it may also be an importer or wholesaler.
Annex II of the ATEX directive addresses design and construction requirements for equipment and protective systems. However, the specific technical requirements to demonstrate compliance for various types of equipment and operating environments are found in nearly 100 individual harmonised standards. Depending on the equipment and its intended use, this means that more than one harmonised standard may be applicable to the evaluation and certification process. Updated harmonised standards lists are published periodically in the Official Journal of the European Union.
Annex I identifies three equipment categories, which depend on the environment in which the equipment is to be used:
- Cat 1 – areas which have an explosive atmosphere present continuously, for long periods or frequently
- Cat 2 – explosive atmospheres likely to occur in normal operation occasionally
- Cat 3 – where explosive atmospheres are not likely to be present in normal operation but, if it does occur, will persist for a short period only
Cat 1 and 2 electrical equipment must be tested and certified by an EU Notified Body (NB), and an NB-certified quality system must also be maintained. Cat 2 and 3 non-electrical equipment do not require NB involvement, but technical documentation must be stored with an ATEX NB.
The IECEx Scheme
Equipment certified in connection with the voluntary IECEx Certified Equipment Scheme meets the regulatory requirements of more than 30 countries. In addition, the IECEx System has been endorsed by the United Nations Economic Commission for Europe (UNECE). As a result, non-IECEx member countries can implement legal frameworks into their respective national legislation, simply by adopting the IECEx System and Schemes. Under the System, regulatory authorities in member countries accept certifications issued by IECEx-recognised Certification Bodies, regardless of their location.
The IECEx conformity mark is intended to provide greater assurance for governments, safety regulators, customers, industry and end users operating within explosive atmospheres.
The following certification schemes are included in the IECEx System:
- IECEx Certified Equipment Scheme
- IECEx Certified Service Facilities Scheme
- IECEx Certificate of Personnel Competence Scheme
- IECEx Conformity Mark Licensing System
The primary goals of the IECEx Scheme are to reduce testing and certification cost, speed up market access for new products and equipment, and increase international acceptance of product assessment results. The Scheme achieves these goals through the issuance of an International Certificate of Conformity based on:
- Testing and assessment of equipment samples for compliance with applicable international standards.
- Assessment and auditing of a manufacturer’s quality assurance system.
- On-going surveillance audits to ensure continued compliance.
Under the IECEx Scheme, testing and assessment activities are carried out by IECEx-approved Testing Laboratories, with certifications issued by IECEx- approved Certification Bodies. Assessment is based exclusively on compliance with standards issued by Technical
Committee (TC) 31 of the International Electrotechnical Commission (IEC).
Self-certification of products is not accepted under the IECEx scheme. Equipment certification under the IECEx Certified Equipment Scheme is based on a compliance assessment with the technical requirements found in the IEC 60079 series of standards (electrical products); the IEC 80079 series of standards for non-electrical products; and the application of quality systems which have been developed by TC 31. However, the IECEx scheme only assesses electrical equipment against the technical requirements of IEC standards issued by TC 31. This restriction can present an insurmountable hurdle for manufacturers of highly specialised electrical equipment, for which a relevant standard does not yet exist.
The IECEx Scheme classifies equipment according to the hazardous environment areas where specific equipment can be used. Equipment Protection Level (EPL) Ga/Da and Gb/Db corresponds with the ATEX Categories 1 and 2 respectively, while Gc/Dc corresponds with the requirements of ATEX Cat 3.
The IECEx conformity mark is evidence that a manufacturer’s products have been independently assessed against the additional requirements of the IECEx conformity mark licensing system. The mark license number is issued to a manufacturer by an accepted IECEx certification body (ExCB) that has entered into a mark license agreement with the IEC.
The use of IEC standards and independent third-parties for testing, assessment and certification are essential elements in the widespread acceptance of IECEx- certified equipment. Indeed, in countries that do not participate in the IECEx System, or which still
require separate national testing and certification, IECEx equipment tests and assessment reports are widely accepted by regulatory officials, which may eliminate the need for duplicate testing.
The ATEX Directive’s conformity assessment process provides a certification route for a broad range of electrical and non-electrical equipment. It also offers significant latitude in the technical assessment of non-conventional equipment through the use of a technical construction file. This can be especially important to manufacturers of customised equipment, or equipment specifically designed for unique applications.
Other considerations include restrictions on the use and acceptance of previously generated ATEX test data. Under the IECEx Scheme, equipment must be tested and certified by IECEx-approved Testing Laboratories and Certification Bodies, and evidence of prior testing conducted by an EU Notified Body is not acceptable. However, EU NBs located in IECEx member countries are required to accept test reports generated by IECEx-approved Testing Laboratories in support of an ATEX certification submittal.
Given these considerations, the preferred conformity assessment path for many manufacturers has traditionally involved first obtaining equipment certification under the IECEx Certified Equipment Scheme. The IECEx testing data is then be submitted to an EU NB as part of the ATEX certification process. This path would still require that certain ATEX- specific requirements are met, such as those related to equipment marking and documentation. However, the effort involved is relatively small compared with other alternatives.
Many consider the ATEX and IECEx to be separate regulations that have little in common and their different requirements and assessment approaches can complicate the regulatory approval process. However, last year the ExTAG (Ex Technical Advisory Group) and ATEX ExNB groups took an unprecedented step forward towards harmonising requirements for both systems.
ExTAG Decision Sheets cover mandatory Ex testing and certification requirements under the IECEx scheme. The sheets‘ use and application are mandatory within the IECEx scheme. They not only deal with application and interpretation of IEC standards used in the IECEx scheme but also with IECEx system rules.
ExNB is the European equivalent to the ExTAG Group and is comprised of a group of experts from the Notified Bodies listed under the ATEX Directive. It was established to ensure that Notified Bodies apply ATEX requirements in a uniform way, and its guidelines are published as Clarification Sheets.
Last year, a leap forwards to harmonising requirements for both systems was made. In order to achieve a common position, it was agreed between ExTAG and ExNB that they would both exchange information and align requirements between ExTAG Decision Sheets and ExNB Clarification Sheets. This was laid down in clause 3 of OD 008/Version 1, which defines the reciprocal arrangements for the exchange of information and meeting participation between ExNB and IECEx.
“last year, a leap forwards to harmonising requirements for both ExTAG and ExNB systems was made”
The ExNB Group has therefore issued Clarification Sheet ExNB/CS/010 containing a list of 43 approved IECEx ExTAG Decision Sheets that must now be used in order to comply with the essential health and safety requirements of ATEX Directive. Annex A of the same document comprises a list of ExTAG Decision Sheets that are not relevant to ATEX due to their reference to IECEx scheme rules, or where IEC standard requirements are different from EN harmonised standards. This list currently encompasses some 100 ExTAG DS.
It is also important to remember that new approved ExTAG Decisions, that were published on the IECEx homepage but not yet as ExNB Clarification Sheets, are not applicable in the EU. This is because the ExNB Group first has to officially accept and publish them in an updated ExNB Clarification Sheet. This could mean that manufacturers applying for certification of a product for both schemes simultaneously might find themselves in a situation where for the IECEx assessment they have to use the most recent ExTAG Decision Sheets issues, whereas during the ATEX evaluation only officially published Clarification Sheets by the ExNB Group can be applied.
To further complicate matters, three ExTAG DS published this year – DS 2020/001, DS 2020/002 and DS 2020/004 – contain new interpretations of IEC 60079-0 and IEC 60079-7, which deal with the use of equipment in explosive atmospheres. As these have not yet been transformed into ExNB CS for ATEX, equipment manufacturers going through simultaneous ATEX and IECEx approvals may find themselves in the predicament that for the same requirements different interpretations of test standards may apply.
“some applications may prioritise light output under emergency conditions, while others may require an extended running time by using a lower output level”
Emergency Ex lighting
Emergency Ex lighting, which has been designed and certified suitable for its specific hazardous location, requires a supply back-up illumination using an in-built battery which will provide an output in the event that mains power is lost.
Safety is obviously the biggest driver behind the need for emergency lighting. Although the presence of gas or dust denotes a ‘hazardous area’, applications in which Ex lighting is required, such as offshore oil and gas, are also commonly high risk in terms of their general safety. The highest safety measures are therefore required at all times to minimise the risk on-site. Given the dangers during total blackout, a lighting solution which guarantees output even when mains power is down, is critical to safety.
The need for emergency lighting is made greater if a site has an unstable power supply. For example, offshore applications rely on the use of generators as their primary source of power. These generators are often unstable and prone to power outages which increases the reliance on emergency lighting and makes the choice of LED luminaires even more important. With existing technology, even short-term voltage drops cause significant disruption, due to the delay in the luminaire being able to restrike.
LED luminaires allow an instant re-strike when mains power is lost, ensuring there is absolutely no blackout when the emergency battery kicks in. In comparison, traditional technology may require up to 15 minutes to fully strike when power is lost; a long wait under emergency conditions and in a hazardous environment. As an LED luminaire can move seamlessly between mains power and emergency mode, they provide the perfect solution to applications with unstable power supplies.
The emergence of LED technology has therefore meant that emergency Ex lighting has become a feasible, functional lighting solution. Although it’s not impossible to find an emergency variant of a traditional luminaire (i.e. SON or Metal Halide), these units have their limitations. However, the size and weight of the emergency batteries tend to be excessive, while they also command a higher cost. As a result, emergency lighting using traditional technology is rare and tends not to be a feasible option for end users.
In contrast, LED luminaires require only a fraction of the power. The saving on power means an emergency backup battery does not need to be as powerful, allowing the use of a smaller, lighter battery which keeps the size and weight of the luminaire to a minimum. This also helps to reduce the cost of the luminaire.
Even if the size and weight of a traditional emergency unit isn’t a problem, or the cost not a barrier, the functionality of the units still poses problems. A high-power draw means that under emergency conditions the units can only provide output for a fraction of the time compared to a superior LED alternative.
Emergency LED luminaires also provide greater flexibility than traditional Ex lights. Each application is likely to have different requirements for its emergency lighting; some may prioritise light output under emergency conditions, while others may require an extended running time by using a lower output level.
As explosions can cause loss of life, serious injuries, and significant damage to site, equipment and stock, it is vital that electrical and non-electrical equipment which is intended for use in potentially hazardous environments contributes to the overall safety of that environment.
Equipment certified for compliance with the essential requirements of the ATEX Directive (2014/34/EU) or the IECEx Certified Equipment Scheme provides assurances that the equipment does not introduce additional risks, or compromise other efforts to ensure safety. The effective prevention of the release of dangerous substances that create explosive atmospheres, as well as preventing sources of ignition to reduce the risk in the workplace are fundamental to avoiding the potentially severe consequences of an explosion.