olemus
maanduse tähis elektriskeemil
=the symbol of grounding in circuit diagrams

ülevaateid
https://www.ni.com/en-us/support/documentation/supplemental/18/chassis--earth-and-signal-grounding--terminology-and-symbols.html

https://incompliancemag.com/article/the-grounding-symbols/

https://electronics.stackexchange.com/questions/67894/use-of-ground-symbols-in-circuit-diagrams

näiteid
https://duckduckgo.com/?q=%22grounding+symbol%22&t=h_&iax=images&ia=images

chassis ground -- massiühendus, kereühendus
earth ground -- maandus
signal ground -- signaalimaa; digitaalmaa