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With low-voltage plug connections, the rated voltage is limited to no more than 50V, serving as a protection measure for use under difficult conditions, such as in pipeline construction, power plant construction, protected areas and boiler operations.

Differentiation of voltages and frequencies by virtue of base notches


CEE plug connections below 50V have an additional auxiliary notch, which is used alongside the base notch, thanks to the lack of the earth contact which is not required. The base notch is always arranged at the 6 o'clock position. The auxiliary notch is assigned a clock position according to the voltage and frequency value.

Contact sockets of sockets and couplings with rated operating voltages up to 50V must be arranged as defined by DIN EN 60309-2 and standard specification sheet 2-VIII.

The different widths of the base notches (4 mm for 32/30 A-connectors and 7 mm for 16/20 A-connectors) prevent 32/30A plugs being inserted into 16/20A sockets.

As per the standard and possible - provided the voltage and frequency are identical - is the connection of 32/30 A plugs into 16/20A sockets and of 2-pin plugs into a 3-pin socket.