Technical Guidance Note 31

TOPIC: Upgrades to existing systems.

ISSUE: 2

REVISION DATE: 27.1.98

PREVIOUS REVISION DATE: 12.2.96

BACKGROUND: Many system suppliers have systems in the field which have been operating for many years and which of course may not be compliant with the essential protection requirements. A customer will often require an update or extension to such a system but will insist that the upgrade parts (note: not the spare parts) which are supplied are identical to those already in service.

PROBLEM: How does the supplier discharge his obligation under the EMC Directive when the demands of the customer are in direct opposition.

GUIDELINES: Any modification to a system that is in use or has been taken into service is defined as "manufacture" if it "substantially alters the EMC characteristics of the apparatus" (see UK SI 1992 No. 2372 regulation 3). On this basis it is up to the manufacturer to decide whether or not this is applicable to the product.

If he decides it is then:

The question is how does he CE mark the product and what constitutes the "product". Logically it is the complete apparatus as modified. It is often not possible to test the apparatus, particularly if it is installed and cannot be moved (in most cases it will be unlikely to meet the current standards).

"Does the manufacturer have to upgrade the complete system to comply with the standards?" He can opt to certify either the system as modified or the upgrade kit for the modification via the TCF route. The justification for the conformity will be the conformity of the "in service system" and would need to be based on the provision of historical evidence showing that there have been no (or few which have been solved) EMC problems with the system. Upgrading is therefore an extension by the installation of like equipment. This is acceptable from a legal standpoint as the manufacturer can (justifiably) claim conformity with the essential requirements of the Directive, but not on the basis of conformity to published standards. Conformity will be by use of the historical evidence.

SUPPORTING INFORMATION: A starting point for the analysis of worst case might be based upon the range of configurations actually sold.

Disclaimer
No responsibility or liability can be accepted by the EMC Test Laboratories Association or any of its officers or members for the contents, specifications and/or advice referred to or contained in this Technical Memorandum and/or action taken as a result of information contained in this Technical Memorandum. Note that:
1. The Association is not by supplying this Technical Memorandum providing professional advice or guidance to any specific party on any specific matter and no legal relationship is created by the provision of this Technical Memorandum.
2. Parties should take specific advice when dealing with specific situations and consult their own professional advisors in this regard.
3. Members are free to deviate from the above guidelines where they think it appropriate, unworkable, or not commercially viable. Under these circumstances, the EMCTLA Secretariat should be informed of the reasons for the deviation so that the matter can be reviewed.