Practice Makes Perfect

I Good EMC

Keith Armstrong of EMC Standards explains the need to employ good EMC engineering practice pervasively for fixed installations.

❱ ❱ EMC compliance of fixed

n the European Union, the EMC Directive requires all “fixed installations” to employ “good EMC engineering practices”, as do all national electrical codes (BS 7671, the IET Wiring Regulations, in the UK), and EN 62305 requires the use of good EMC engineering to protect all equipment on sites against damage from lightning. If non- compliance is discovered, site insurance could be problematic.

FIXED INSTALLATIONS A “fixed installation” can be a commercial or industrial site; national infrastructure such as electrical, telephone, internet, road or rail networks; or a system within a building, such as a lighting system, computer network, HVAC system, production line, etc. The EMC Directive requires the owners or operators of each fixed installation to appoint a “Responsible Person” to oversee its EMC compliance. Some sites might have a single person responsible for everything; others might have several people, each responsible for different fixed installations. Each responsible person must ensure their fixed installation does not interfere with radio, telecommunications and other equipment, and operates as intended despite the Electro- Magnetic Interference (EMI) in its operational environment. They must also ensure that good EMC engineering practices are used and apply the EMC installation/use instructions provided with supplied equipment. These activities must be documented, and the documents kept ready for inspection by national EMC authorities for the operational life of the fixed installation.

RESPONSIBILITY CAN’T BE DEVOLVED EMC enforcement agents have the authority to immediately close down fixed installations that they think cause EMI problems, and have done so after receiving complaints of EMI. Maintenance and engineering contractors and installers may

see good EMC engineering requirements in their contracts but need to understand that the EMC Directive only applies to a fixed installation’s owners or operators. So, for example, a specification: “The work must comply with the EMC Directive” is meaningless because no contract can make a law apply to someone not covered by that law. A specification that states: “Good EMC engineering

practices must be used” is also meaningless, because the good 20 /// EMC Testing Vol 1 No. 2

installations is the responsibility of the owner or operator rather than the maintenance subcontractor

❱ ❱ Keith Armstrong of EMC Standards advocates a detailed approach to ensuring the compliance of fixed installations to regulatory requirements

EMC practices required depend on a site’s electromagnetic environment, and how the responsible person wishes to control EMI issues.


A problem with the EMC Directive, national electrical codes and EN 62305 is that they do not describe all the practical good EMC engineering details that are needed. So, any specification for subcontract work should specify exactly the good EMC engineering practices required, in practical detail, plus exactly what verification or validation procedures are required (e.g. inspections; in-situ EMC testing, etc.). For example, many mistakenly believe that good EMC engineering requires the use of single-point (‘star’) earthing/ grounding systems; terminating cable screens at only one end; and connecting filters and cable screens to earth/ground using any length green/yellow insulated wire. But these techniques are decades out of date and are now bad EMC practices in general and recognised as such in relevant standards. There is also the mistaken idea that constructing systems

and installations from CE-marked equipment and following their suppliers’ instructions is all that has to be done for EMC – the so-called “CE + CE = CE approach” – but this has no technical or legal basis. Another mistaken belief is that complying with the EMC Directive also takes care of functional safety risks caused by EMI – which it does not. With the control of all aspects of our lives, including safety, increasingly being entrusted to immensely complex – and often totally autonomous – electronic systems of systems, the risks of EMI to human safety are increasing very rapidly too. There is no escaping the fact that we all need to learn and apply good EMC engineering practices. n

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