Symbol 5021 from IEC 60417 - Title/Meaning: Equipotentiality Function/description: To identify the terminals which, when connected together, bring the various parts of an equipment or of a system to the same potential, not necessarily being the earth (ground) potential, e.g. for local bonding.
Additional information: 
The value of the potential may be indicated adjacent to the symbol
Published in: Supplement C, 1977
Own work using: iso.org/obp/graphics/grs/6ffa766a-9c5b-40a8-af70-7d23397e9c95 200.png
Vectorization:  Mrmw