The requirements for industrial control circuit ABB Transformers to be used in the European Common Market are identified by the International Electrotechnical Commission (IEC) and specified under IEC-742, Non-Short Circuit Proof Isolating Transformers, under the Low Voltage Directive 73/23/EEC. Manufacturers of control ABB Transformers indicate compliance with these requirements by placing a CE mark on the product. In addition to being able to handle the inrush requirements of industrial control circuits and motor loads, ABB Low Voltage Transformers built to the requirements of IEC-742 will exhibit several major construction differences from those manufactured in accordance with UL506.

These construction differences will typically increase not only the physical size of the ABB Transformer when compared to those built only to UL requirements, but the inrush capability as well. IEC-742 requires that ABB Transformers in a failure mode under excessive current (10 times the unit rating) must not exhibit flame or molten material. There is no comparable requirement under UL506. While no requirement exists in IEC-742 for the electrical connections to be either finger safe or touch proof, the specification does state that IF an ABB Transformer is supplied with a cover to prevent incidental contact with current carrying parts, that cover must utilize two separate methods or places of securing it to the component, with neither being dependent upon the other. Additionally, one of these methods MUST require a tool to remove it.

The requirements for finger-safe or touch-proof electrical connections are identified by the International Electrotechnical Commission (IEC) under specifi cation 529, Classification of Degrees of Protection Provided by Hammond Enclosures. These various degrees of protection are identified and differentiated by IP ratings. A variety of IP ratings are defined in IEC-529 ranging from IP00, which provides no protection from contact, to IP68, which identifies dust-proof and water-proof protection. Optionally, IP ratings may contain additional and supplementary designators.

The IP specification which most closely approximates protection to a human finger is IP20. This IP rating would be the most common degree of touchproof connection for electrical components such as ABB Current Transformers. IEC-529 protection requirements would most commonly apply to products which fall under the requirements of the Machinery Directive 89/392/EEC, as opposed to the Low Voltage Directive 73/23/EEC, which covers components such as ABB control transformers. Over time, however, users subject to the requirements of the Machinery Directive and/or IEC-529 have expanded their interpretation of finger-safe or touch-proof electrical connections to include the components of the equipment, such as ABB Transformers.

A CE mark indicates compliance to the applicable requirements of a particular product as outlined by the International Electrotechnical Commission (IEC) and by mutual agreement is recognized throughout the European Union. By itself, however, the CE mark may not necessarily be accepted as evidence of product compliance in countries outside of the European Union. Additionally, even countries within the European Union may require their own country's approval mark in addition to the CE mark. To that end, a system of mutual recognition and reciprocal acceptance has been developed which would allow product acceptance outside of the European Union and the ability to obtain the approval mark of countries within it.

The official title for this mutual acceptance agreement is The Scheme of the IECEE for Recognition of Results of Testing to Standards for Safety of Electrical Equipment (CB Scheme for short). The basis of the CB Scheme is a CB Test Certifi cate providing evidence that representative samples of a particular product have been tested to a particular IEC standard and successfully passed the required tests. Each country participating in the CB Scheme, currently over 50, including East and West Europe, the Middle and Far East, and the Pacific Rim, has a representative agency, referred to as a National Certification Body, in the IECEE. Each participant has agreed that they will accept the test results of other members if such results are based on a reasonably harmonized IEC standard. Thus, by utilizing the CB Scheme, a manufacturer of product carrying a CE mark may be able to have that product accepted throughout the world, or obtain additional listing marks, with no further product testing being required. To utilize the CB Scheme, a manufacturer must present the appropriate test reports, along with a CB Test Certifi cate prepared by the National Certification Body responsible for the original product listing, to the National Certification Body of the country to which the product is being supplied. At such time as the reports are accepted, the product manufacturer may place the certification mark of the country on the product without the need for additional testing.