The DIN Rail and How It Got That Way

Unless you’ve spent some time in the industrial electrical field, you might be surprised at the degree of integration involved in the various control panels needed to run factories and the like. Look inside any cabinet almost anywhere in the world, and you’ll be greeted by rows of neat plastic terminal blocks, circuit breakers, signal conditioners, and all manner of computing hardware from programmable logic controllers right on to Raspberry Pis and Arduinos.

A well-crafted industrial control panel can truly be a thing of beauty. But behind all the electrical bits in the cabinet, underneath all the neatly routed and clearly labeled wires, there’s a humble strip of metal that stitches it all together: the DIN rail. How did it come to be, and why is it so ubiquitous?

Standards, Please

The development of what would become DIN-rail and the terminal blocks and accessories that mount to it closely tracks the early phases of industrial electrification. As motors and other components become more and more essential to industry, so too did the need for something sensible to connect everything together. Early control panels were a mish-mash of whatever terminals could be found, often plain nuts and bolts in some kind of expedient insulator. Panels were tedious to construct, hard to maintain, and prone to failure.

The original Hugo Knüman “RWE Terminal Block” and rail. Source:

To mitigate these problems, in 1928 an electrical utility in Germany called Rheinisch-Westfälisches Elektrizitätswerk (RWE) contracted with a supplier of electrical products to develop a new modular terminal blocks system. The young company was called Phönix Elektrizitätsgesellschaft and its founder Hugo Knümann worked closely with engineers from RWE to solve the terminal block issue. (Ordnung muss sein!)

What they came up with was a small porcelain tray containing a metal bus bar. The bar made a connection between two wires through screw terminals, and the porcelain held it firmly. The blocks were designed to be closely packed into long strips, but with only one side of the block enclosed by the porcelain, some way to prevent shorts in case an adjacent block were to be accidentally installed backward would be needed. This requirement,…

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Peter Bordes

Exec Chairman & Founder at oneQube
Exec Chairman & Founder of oneQube the leading audience development automation platfrom. Entrepreneur, top 100 most influential angel investors in social media who loves digital innovation, social media marketing. Adventure travel and fishing junkie.
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