NE 23 has been revised

The NAMUR Recommendation NE 23 has been revised in a joint working group of NAMUR and VIK and may now be obtained from the NAMUR Office.

The document differs from NE 23 edition 2004-04-07, which was withdrawn since March 2017, as follows:

• Editorial revision in separate German and English versions
• No significant technical changes
• Update of the cited standards
• Adaptation of terms and definitions

Abstract NE 23 ‘Extra Low Voltage Circuits with Safe Separation’
(Edition: 2019-09-09)

Protection against electric shock as described in DIN VDE 0100-410 (VDE 0100 part 410) shall be provided for all electrical equipment and circuits irrespective of the level of the nominal voltage.

When selecting protective measures for the circuits of control and instrumentation systems and information technology systems two aims have to be brought into line. First, protection against shock currents has to be ensured, and second, a high availability of the systems has to be guaranteed. It also has to be possible to work on those circuits while the plant is running without having to shut down the supply voltage.

In view of this, the most appropriate solution is a protective measure with extra low voltage. A peculiarity of these protection measures is that they are circuit-oriented and therefore require a holistic system approach. The tasks involved in electrical engineering and control and instrumentation technology require technical solutions combining instruments subject to different safety standards.

The aim of this NAMUR recommendation is to recommend a protective measure described in DIN VDE 0100 part 410 and to explain its application, which consistently meets all safety standards and the requirement of high availability.