Klaus Frank on Nostr: you could want to not use the grounding pin in the plug for example. Or if the switch ...

you could want to not use the grounding pin in the plug for example. Or if the switch is plugged into a UPS then you need to "source" ground somewhere else too.

Sometimes you want to not ground in the building you are currently in but also have a separate ground wire running along. It's not that common these days as it is just way simpler to run a fiber between buildings...