BS EN 61666:2010+A1:2021

What is BS EN 61666 about?  

BS EN 61666 establishes general principles and gives specifications like terminal designation and classification of terminals, for the identification of terminals of objects within an industrial system. 

BS EN 61666 is applicable to all technical areas like mechanical engineering, electrical engineering, construction engineering, and process engineering. 

Note 1: Requirements for marking of terminal designations on products are not part of BS EN 61666. 

Who is BS EN 61666 for?  

BS EN 61666 on identification of terminals within an industrial system is for: 

• Terminal block manufacturers 
• Suppliers and dealers of terminal blocks 
• Designers of terminal sets 

Why should you use BS EN 61666?  

A terminal of an object can be associated with more than one terminal designation and the object to which the terminal belongs can at the same time be associated with a reference designation set.  

A terminal block is a tool used to safely connect two or more wires together. BS EN 61666 on the identification of terminals gives you information about the designation and classification of the terminal blocks.  

The principles stated in BS EN 61666 can be used for systems based on different technologies or for systems combining several technologies. Each specific block type may be used for various applications, but they all provide you with the same function of connecting electrical components in a safe, reliable manner. 

What’s changed since the last update?  

BS EN 61666:2010+A1:2021 supersedes BS EN 61666:2010, which is withdrawn. BS EN 61666:2010+A1:2021 includes the following substantial changes with respect to the previous edition: 

• The terminology used in the publication has been adapted  
• A more comprehensive description of the designation principles is provided 
• Additional examples illustrating terminal designations related to the function aspect and location aspect are provided 
• An additional example illustrating the use of terminal designation sets is provided 
• The former informative Annex A has been turned into a clause in the standard