The Technical Construction File provides one way of demonstrating compliance with the EMC Directive when the standard route to compliance is not always the most appropriate : the harmonised standards are not applicable to every product in every situation.

The route involves a third party in the assessment of the product. Competent Bodies have been appointed in each EC member state to analyse equipment in the environment in which it is used and make judgements as to whether product meets the essential requirements of the EMC Directive.

A manufacturer presents evidence on his product to a competent body in the form of a technical construction file (TCF). This document is the only evidence a competent body has that a manufacturer's product is compliant.

The TCF shall describe with sufficient detail how the product is constructed and its performance. When the Competent Body has examined the TCF, assuming that it is happy with the contents, it issues a technical report with a certificate, or a certificate on its own, confirming that the product complies with the essential requirements of the Directive and the manufacturer should then make a declaration of conformity.

The TCF shall be kept at the disposal of the competent authorities for ten years following the placing of the apparatus on the market.

In brief, a Competent body can or must be used by a manufacturer in the following situations:

• Where harmonised standards do not exist.
• Where standards exist but are not practical.
• Where product variants exist.
• Where foreign certificates exist and/or
  Where harmonised standards exist but the manufacturer chooses not to use them.