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The terminal block (Wago 2003-7641) illustrated below has a neutral connection that can be grouped using a bus bar. This makes sense. However, the blue plastic block below can be used to disconnect the neutral of a particular block by moving it.

Question: what exactly is the purpose of this? I understand disconnecting the live connection, but why would you want to disconnect the neutral, why would a terminal block offer this option?

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Dmitri Nesteruk
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I can think of a few reasons one might want/need to isolate the neutral.

  1. Depending on the situation and local regulations, the neutral may or may not be regarded as safe to touch during maintenance work. If it is not regarded as safe to touch then there needs to be a way to isolate it.
  2. If there is a RCD upstream then performing maintenance work without isolating the neutral carries a high risk of tripping said RCD due to accidentally creating a neutral to earth fault.
  3. to perform insulation testing on the downstream wiring the neutral will need to be isolated.

That said, a method of disconnecting the neutral which is not physically linked to a means of disconnecting the corresponding live conductor carries risks of it's own. You will need to evaluate whether such a disconnecting means makes sense in your environment.

Peter Green
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