Can someone explain to me why the symbol of the valve arrester has a short circuit, if it is already earth? I don't understand why it is depicted like this.
Why does the valve arrester have the symbol of a short circuit joined with earth? Does it mean that it is a short circuit to earth?
Note: The CD symbol is a streamer, equipment which measures current.
Context: I posted a previous question: Meaning of this power system line diagram symbol. That question was to ask what the termination symbol was. Now I understand that. This question is asking why in a valve symbol, with a streamer, there IS a termination symbol or a short circuit symbol as in the link cited above, and why is this symbol followed by the earth symbol and not only the valve, streamer and the earth?
Summary: I would like to know why they put a termination symbol and an earth symbol.