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NKYS1612 Date: 161202 © J. M. Woodgate 2016
KNOW YOUR STANDARDS: PART 1 & 2
Where do standards come from and who produces them?
Contrary to popular belief, standards are not produced by bureaucrats in Brussels or apparatchiks in Geneva, but by industry people like you and me (especially me!). Of course, we are hired for our talents at electronics, not for our literary skills, so sometimes our writing falls short of the lucidity that is, nevertheless, essential in a standard, especially one that is associated with legislation or regulation, and that particularly includes standards for safety and for EMC.
What this amounts to is 'Don't suffer in silence.' When you find something in a standard that isn't comprehensible, or is comprehensible but cannot possibly be meant, please don't just fume and ignore it; tell someone involved with that standard, or even me. It may take a while, but it will be fixed. If you are an IEEE member, the EMC-PSTC mailing list can be extremely helpful, especially for the requirements of countries outside Europe
There are two groups of international standards bodies:
those established by treaty, or as organs of the United Nations, or by special international agreement, such as IEC (including CISPR), ISO and ITU. ITU is split into ITU-R, which produces non-mandatory requirements for broadcasting, and ITU-T, which produces requirements that it intends to be mandatory, for telecommunications;
those which are learned societies with international membership of individuals, such as IEEE and the Audio Engineering Society.
You might well conjecture that, on the basis of the perversity of human nature, that there is a degree of xenophobia between these two groups, but they do talk to each other.
CISPR (abbreviation of the French title) is part of IEC, but has a different Constitution, allowing government agencies, normally the spectrum management authorities, to be members, in addition to national standards bodies.
ETSI (European Telecommunication Standards Institute) appears from its title to be a Regional body, but it is a private membership organization, not a government agency, and has members from all over the world. Its importance has recently been greatly magnified by the spread of embedded radio transceivers in products that previously had no wireless communication and by the introduction of the EU Radio Equipment Directive (RED) with an extremely broad scope, replacing the far more limited RTTED (Radio and Telephone Terminal Equipment Directive) at extremely short notice.
Two bodies in this category are the European CENELEC (dealing with most electrical and electronics matters) and CEN, dealing with everything else. Their declared policy is to adopt IEC or ISO standards, respectively, wherever possible. 'Common Modifications' can be agreed by all participating countries, while 'Special National Conditions' are allowed where legal or major infrastructure requirements in particular countries make them necessary.
Every developed state, and most emergent states, has a national standards body, which is a member, or associate, of the international bodies. The UK Government is the ITU member, BSI is the ISO and CEN member, and also the member of IEC and CENELEC.
The British Standards INSTITUTION
Not 'Institute'! BSI is one of the oldest standards bodies and sometimes it shows. But Greek standards for metal parts used in masonry work were in place in Classical times (around 360 BCE)!
Most BSI committees parallel the work of international or regional committees. For example, BSI GEL/210/11 parallels IEC SC77A, SC77B and SC77C, and CISPR A, B, D, F, H and I. Membership of BSI committees is not very difficult to achieve, but you do tend to 'need to know someone', simply because it's not obvious how to apply. Not that there is often a queue of eager aspirants! However, unlike in almost all other countries, committee membership (as opposed to subscribing membership of BSI) is FREE. All you need to do is to devote your (employer's?) time and travel costs. If the committee sends you to a regional or international meeting, you may qualify for a government travel grant (AITS), which, in these days of budget air travel, may pay for a good percentage of the total cost.
Why standards matter for compliance
There are few countries in the world now that will allow products to be marketed without meeting requirements for safety and EMC (and maybe other things). While some require compliance with national standards, and others require testing in an indigenous laboratory, the demands for trade restrictions to be removed is strong enough to force the acceptance of IEC standards, or the substantial alignment of national standards with the IEC standards. There is also a growing number of mutual recognition agreements (MRA) between agencies, meaning that they accept test reports from laboratories in each other's country.
Free trade and legal issues have also resulted in the abandonment, for most purposes, of mandatory compliance with standards and, to a large extent, mandatory third-party testing. The result is that the manufacturer bears the whole, non-delegatable responsibility for a product being safe and having sufficient electromagnetic compatibility, but can demonstrate that by any means that he wishes and expects to be acceptable to the market surveillance authorities.
The importance of 'design in' and the availability of standards at the 'solder face'
It seems incredible that there are still companies who either don't buy any standards or keep them locked up in the Technical Director's office. They hand over a 'finished' product from the design engineers to specialist safety and EMC experts, who proceed to re-design it, at huge cost and with a long time delay, in order to comply with what they think are the mandatory regulations, because even they don't have free access to the standards and subsist on information from colleagues and the web, much of it not exactly wrong but misleading because of incompleteness.
It seems so obvious that the right way is to 'design-in' safety and EMC compliance from the beginning of the design process, with the experts involved at all necessary stages. In order for the designers and experts to talk the same language, and, especially, to prevent conflict, they must all have ready access to the relevant standards. If not, they soon begin to suspect that each expert has a personal agenda and is not just ensuring that the product complies. There isn't actually anything wrong with personal agendas, if they are in the open and recognized for what they are. For example, how close to an EMC limit is 'too close for comfort'? The EMC expert may well say that from experience, this sort of product needs a 5 dB margin, whereas this sort needs only 3 dB.
How to obtain standards
ETSI standards are FREE and can be downloaded from http://www.etsi.org/ In many cases, the EMC standards come in pairs, one of general application and the other a version that satisfies the 'essential requirements' of whichever EU Directive it supports.
You can, of course, buy standards from BSI. Be cautious about buying from 'official agents' – their mark-ups can be quite large. If you buy from IEC or ISO, you may be able to buy only a bilingual publication, (English and French), which naturally costs more than for one language. Some IEC standards are published in Spanish.
Because of the 'Common Modifications' and 'Special National Conditions' mentioned above, the CENELEC or CEN adoption of an IEC or ISO standard is NOT identical to the original. How important the differences are depends crucially on what product is being considered. A detail that is of no significance at all for one product can require a substantial re-design of another. In addition, there are almost always differences in the 'Normative References' – standards mentioned in the text which give information on, for example, the methods of measurement that must be used. EMC ENs also have an Annex ZZ about how the standard matches up to the Directive.
ENs in English can be purchased from the national standards bodies of other European countries, often at attractive prices. There is a comprehensive article, including a web-site linked list of standards-making bodies, at:
The Estonian standards body (https://www.evs.ee/shop) offers many standards in English on a variety of financially attractive terms.
Participants in BSI's national and international standards work are given access, with restrictions, to the standards in their area of work. BSI Project Managers can give committee members access to related standards if they are needed for reference in connection with work on another standard.
What do you do next?
Having obtained your standard, you put it in a safe place, intending to read it later, don't you? Preferably not! The plot is thin and the characterization poor, so it's only a bit better than the average TV play, but you need to read it carefully, and not once but several times, with your product in front of you, so that you can see how each clause of the standard relates to your particular concerns. This applies also to the Normative References – standards having provisions that are effectively provisions of the standard you are reading. There may be many of these, and you don't have to buy them all. You look at each reference where it appears in the body of the standard, not in the Normative references clause, and consider whether your product is affected or not.
If there is anything you don't understand, or think it makes no sense, do ask advice, from colleagues or wider on the Internet.
NKYS17-01 Date: 17-01-30 © J. M. Woodgate 2017
KNOW YOUR STANDARDS Part 2
by J. M. Woodgate B.Sc.(Eng.) C.Eng. MIET SMIEEE FAES Hon FInstSCE
More (and more!) standards-making bodies
There is another way of classifying standards-making bodies, which does not fit too well with the natural progression International - Regional - National, so is best treated separately. This classification distinguishes between those bodies which may roughly be described as 'public institutions' (into which fall ITU, IEC, ISO, CENELEC, CEN and most National Committees) and those that are substantially privately-constituted bodies, which have a fee-paying membership. We dealt with the former type last time, but mentioned only ETSI and learned societies in the context of membership bodies. There are three main types of such bodies.
Other membership bodies that are also standards-makers include IEEE and the Audio Engineering Society, as mentioned last time. There are numerous such bodies, not only learned societies but also trade association and other industry groups, active at the national level, and in some cases their deliverables are adopted as official National standards - this option is available in USA through ANSI, for example. One of the most prominent of these bodies is Ecma International (formerly the European Computer Manufacturers Association, ECMA). Ecma mostly works in co-operation with ISO/IEC JTC1 - the international forum for the IT standards movement. It produces standards and technical reports, which are respected by most of the major IT manufacturers but not all, which is liable to create compatibility problems. Ecma publications are available FREE to all.
A third category of standards body is set up to develop, promote and control a particular technology, and usually includes intellectual property rights (IPR) licensing as part of its activity. There may be only one 'standard' - setting the requirements for interchangeability between products using the technology. One well-known example is the DVD Forum, and others are the USB Implementers Forum and the MIDI Manufacturers Association. There is a huge number of such bodies, some more prominent and successful than others.
These bodies rarely come to the notice of standards users, but are very influential directly on the International bodies, often through shared experts. Many were established a long time ago, when the language of international affairs was French. Those that are often concerned with EMC matters include:
CEPT Conférence Européenne des administrations des postes et des télécommunications
Formed in 1959, this body pre-dates the breaking of the monopolies on telecommunication held by national postal authorities in Europe. It still co-ordinates the postal and infra-structure telecommunications services in a 'Greater Europe' that includes the Russian Federation and Turkey. As such, it is a major player in ITU-T, and was responsible for the creation of ETSI, so you know who to blame.
CIGRÉ Conseil International des Grands Réseaux Électriques (which is not quite so easily guessed in English: International Council on Large Electrical Systems. It really does use accented upper-case letters in the French).
It is a sort of hybrid between a standards-making body and a learned society for the science and engineering of large-scale electric power distribution. Apart from its central organization, it has nearly 60 National Committees. Its 'standards', called 'Technical Brochures', are used directly by members, but also influence IEC committees such as CISPR/B and IEC SC77A.
CIE Commission Internationale de l'éclairage (International Commission on Lighting)
Similar to CIGRÉ, CIE studies the science underlying colour and its perception, but also produces guidance on all applications of lighting, including image technology, so interfaces with a number of IEC and ISO committees. Lighting represents a major use of electric power, and the lighting load has quite rapidly changed from largely resistive incandescent lamps to more efficient, but non-linear compact fluorescent and LED lamps, so CIE has been involved in the applicable EMC standards committees CISPR/F and IEC SC77A.
Producing new standards
Many people think we have far too many standards already, and that is probably true, but finding out which ones we don't need is difficult. Meanwhile, we should only make a new standard if it is justified, and most standard-makers have a procedure for seeking justification; some work better than others. In IEC, at least five (normally) National committees have to vote to accept a New Work proposal AND nominate experts to do the work. In several recent cases, there was ample support for the proposal but too few nominations for experts! It's easy to support a project if you expect someone else to do all the work!
These days, technology moves so fast that a standard could easily be out-of-date before it passes final voting. The minimum practical period for producing a new standard is three years, allowing for one comment stage and two voting stages, as in IEC and ISO. But this works only if the subject is non-controversial and technically rather simple. In other cases, more than one comment stage and more than two voting stages may be required.
Making standards intelligible, unambiguous and accessible
IEC and ISO have quite strict editorial rules, compiled from many years experience, but these can only really impose a uniform structure and, to some extent, control the use of verb forms so as to distinguish between compulsion (shall), recommendation (should), permission (may) and possibility (can). However, the English language being what it is (almost all international standards are drafted in English), it's awfully easy to slip in a 'have to' or 'is to' instead of 'shall'. 'Must' and 'must not' are reserved for compulsion not under the control of the standards-writers, such as the need not to violate the laws of physics. This may all seem very pedantic, but maybe not when you realise that the German 'muss' means 'must', but 'muss nicht ' means 'need not'. And that isn't the same meaning as the 'need not' in the sentence about physics!
Above all, it is necessary to keep the language as simple as possible. To simplify the wording of this article, I'm now going to assume that you have become a new standards writer. 'Simple' means simple sentence construction, not necessarily avoiding long words, as long as they are technical; 'permeability' is OK, but not 'quintessence'! It's awfully easy to use stylistic 'tricks', such as inverted word order or 'tech-speak' - 'speaker' instead of 'loudspeaker' (they are quite different words in other languages), which are blindingly obvious to a native English speaker but very confusing to someone, let's say Mr Sum, who learned three other languages before English. And when you need to write the same thing several times, such as in a test procedure, use the same words every time. You are not writing a homework essay for Mr Beelzebub, the English teacher, to whom repetition is anathema, you are striving not to confuse Mr Sum, who sees different words and wonders what the difference in procedure actually is.
Keeping standards up-to-date
Even if a standard is still up-to-date when it is published, it will not stay that way for long. (Incidentally, the use of 'that way' is an example of what is likely to confuse a standards reader. Write '…it will not stay up-to-date for long.').
IEC and ISO have a formal 'maintenance procedure', which was written up very confusingly in the past but is now explained more lucidly in the latest ISO/IEC Directives. These are the rules of the whole ISO/IEC standards 'game', and to do well you need to know the rules. Luckily, they are free downloads from http://www.iec.ch/members_experts/refdocs/. All three parts, Part 1, Part 2 and the IEC Supplement, are very recently revised, with quite a number of changes, so even if you already have them you probably need to download the new ones.
When a standard is published, it comes with a 'stability date', of 3 to 12 years (in a special case 15 years), when the next version is expected to be published, not when work is to start on the new version. So, if the stability date is only 3 years ahead, maintenance work has to start immediately the standard is published (or even, informally, before then). To start the formal process, a 'Document for Comment' (DC) is (should be) sent to National Committees, recommending re-confirmation, withdrawal or revision. If revision is recommended, an outline of what revision is proposed may be attached. National committees are asked to comment on the recommendation and, in the case of revision, to review their representation on the responsible committee or to nominate members to a new Maintenance Team. When the responses are collated, a Review Report (RR) is circulated to National Committees, explaining what is planned to be done. Unfortunately, the rules allow an RR to be circulated without a DC, which presents National Committees with a surprise (this is the first notice that the standard was considered for amendment, revision or withdrawal) and a fait accompli – the standard's fate has already been decided, without consultation. This is not likely to impress a concerned National Committee.
Some standards deal with technology that is no longer in use – TV picture tubes for example. The associated standards may be withdrawn, and in the past, In ISO and IEC, it was very difficult to obtain a copy of a withdrawn standard even if it was really needed. However, withdrawn IEC standards are now available (but not free).
In other cases, a technology may no longer be in wide use but IS still in use for special applications or for historical and archival purposes.
Note - Some people are very fearful about the future loss of access to stored digital information of high importance, and indeed it has happened - the BBC Domesday project used an adapted form of the Philips Laserdisc technology, but access was very nearly lost through negligence - read the whole sorry story at: http://en.wikipedia.org/wiki/BBC_Domesday_Project
For the relevant standards of this type of technology, IEC and AES have adopted the term 'stabilized standards', which are preserved as current but are not expected to change for at least 15 years. An example is the standard (IEC (60)098) dealing with vinyl disc playback, which is undergoing a huge come-back at present.
Over the last two issues, we looked at the standards-making bodies and their characteristics, how one can obtain standards economically, what to do with them when you have them (most important!) and how one can participate in standards work (masochism is not essential, but it helps).
Types of standards publication
There is a problem with terms, because the word 'standard' is used, even by standards-making bodies, to mean various sorts of publication, only one of which is a 'standard' as normally understood, i.e. a prescriptive document, using 'shall' as the verb for its provisions. Not so many years ago, the then edition of BS 0 (BS Zero – 'A standard for standards') listed ten types of publication, and used 'specification' to mean the prescriptive type, which nevertheless are called 'standards'. Furthermore, the terms differ between standards bodies.
IEC and ISO publications
These publications are numbered as IEC [prefix] NNNNN-nn-nnn, ISO [prefix] NNNNN-nn-nnn or ISO/IEC NNNNN-nn-nnn. The '-nn-nnn' refer to Parts and Sections of multipart standards and are absent from single standards. At one time, especially in IEC, the first N was 6, but now other numbers appear in that position for standards on different major topics.
· Standards (no prefix) – prescriptive documents;
· Technical reports (TR) –descriptive documents; under current rules may not even give recommendations, using 'should';
· Technical specifications (TS) – 'wannabe' standards - NOT to be regarded as standards but they can use prescriptive language. May be turned into standards after experience has been gained of their use or they may continue to exist as a 'halfway house';
· Guides (numbered in their own series); in spite of the name, many of them are prescriptive; they concern the content of standards, their relations with other standards and how they are to be developed. They are generated by high-level committees and are addressed to Technical Committees, not normally to standards users.
· Publicly-available specifications (PAS) – documents originated elsewhere that are candidates for adoption as standards after experience has been gained of their use.
There are two suffixes, indicating different variations of the same edition:
· CSV – Consolidated version of a publication with its amendments and any corrigenda;
· RLV – Red line version, including both the 'clean' text of the standard and a marked-up version showing where it differs from the previous edition.
Although CISPR is part of IEC, it has its own Constitution and its own numbering system. Publications are numbered in the form CISPR [prefix] NN-nn-nn. They are published by CISPR sub-committees, not CISPR itself. There seems to be no rule that prevents CISPR sub-committees producing all the same varieties of publication, except Guides, as the rest of IEC, but at present it has only TRs and PASs. Generic EMC standards produced by CISPR/H are numbered in the IEC 61000-6 series.
CEN and CENELEC
These publications are numbered as EN (or TR) NNNNN-nn-nnn, but in CEN, the number of Ns may be fewer. ENs are 'European Standards', not 'Euronorms' which are quite different publications, from a different source.
· Standards (EN) – prescriptive documents;
· Technical reports (TR) – usually descriptive documents, may give recommendations, using 'should', but are definitely not prescriptive;
· Technical specifications (TS) – 'wannabe' standards - NOT to be regarded as standards but they use prescriptive language. May be turned into standards after experience has been gained of their use or they may continue to exist as a 'halfway house';
· Harmonized documents (numbered in their own series HD NNNNN-n-nnn) – prescriptive documents adopted when due to different legal or other circumstances in EC member states, an EN could not be implemented verbatim in all states. The number of Ns is variable. Examples are standards for cables and those for electrical installations, such as BS 7671, which is the British implementation of HD 60364;
· Guides (numbered in their own series);these are not the same as IEC or ISO Guides and are not always prescriptive.
In CENELEC, the first two Ns indicate the origin and nature of the standard:
· EN 50NNN-nn-nnn – a standard prepared and published by CENELEC;
· EN 55NNN-nn-nnn – a standard adopted from CISPR, therefore an EMC standard. The last two Ns and any ns are taken from the CISPR number;
· EN 6NNNN-nn-nnn – a standard adopted from IEC; the 6 may be replaced by another digit except 5;
EN 55NNN and EN 6NNNN standards are very similar to the original CISPR or IEC standards but are never identical; the difference may be trivial or very significant, and that varies from case to case. A difference may be trivial to others but profoundly affect your product.
These standards adopted from IEC or CISPR may include 'Common Modifications', which apply across Europe, and Special National Conditions, which apply only in the states which request them. A few standards still include 'A deviations', which are necessitated by legal provisions or infrastructure conditions that cannot be readily or reasonably changed. In an Annex ZA, the Normative References are replaced by references to ENs and HDs if they exist. Annex ZB usually contains the Special National Conditions, if there are any. EMC and safety standards include an Annex ZZ that details how the standard matches the provisions of the Directive. There may be other important differences (important to your product, if to no other) between the EN and the standard from which it was derived.
There is another terminology problem with this word. Originally, all ENs and HDs were 'harmonized' – meaning 'implemented in all EU states'. But the Commission hi-jacked the term (probably inadvertently and no-one bothered to challenge it) to mean only those standards listed in the Official Journal, conformity with which conveys prima facie evidence of compliance with a Directive.
IEC and ISO standards are recommended to the organizations' members – the national standards bodies – for adoption nationally. They are not 'recommendations' in the sense of being only advisory. Problems have been caused by some National Committees implementing standards that are referred to in legislation, such as safety and EMC standards, immediately on publication by IEC or ISO. A case occurred some years ago where products were legal when put in a ship but illegal when taken out of it in a far country! IEC and ISO do not specify 'transition periods' but call the attention of National Committees in the Forewords of such standards that transition periods may be required at national level so that industry has time to manufacture products conforming to the new standard.
In CEN and CENELEC the procedure is more detailed. National Committees must implement published ENs, even if they voted against them. There is a sequence of critical dates, some of which are listed in the actual publication:
date of ratification (dor)
date when the Technical Board notes the approval of an EN (and HD for CENELEC), from which time the standard may be said to be approved
date of availability (dav)
date when the definitive text in the official language versions of an approved CEN/CENELEC publication is distributed by the Central Secretariat
date of announcement (doa)
latest date by which the existence of an EN (and HD for CENELEC), a TS or a CWA has to be announced at national level
date of publication (dop)
latest date by which an EN has to be implemented at national level by publication of an identical national standard or by endorsement
date of withdrawal (dow)
latest date by which national standards conflicting with an EN (and HD for CENELEC) have to be withdrawn
All these are determined by CEN or CENELEC, but there is also another one, of very high importance, that is determined by the Commission. This is the fabulous beast 'docopocoss' – the (BIG breath!) date of cessation of presumption of conformity of the superseded standard. This is listed against each standard notified in the Official Journal as providing prima facie evidence of conformity with a Directive. A newly-listed standard can be used immediately, but industry has a transition period, usually of three years, before the former standard reaches the docopocoss and may no longer be referred to in Declarations of Conformity.
The docopocoss is normally the same as the dow, but the Commission reserves the right to set a different date, and occasionally exercises that right.