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By CestLaGalere
#87040 I have a setup with a 3 wires in a buried cable going to a watering valve.
I have a esp8266 with relay to switch this from a 24v ac bell transformer, the esp8266 uses a separate 5vdc supply
I'd like to power a sensor at the same point as the valve that needs 5vdc, but only have the 3 cables, will be a pain to rebury.

Is it OK to make one of the 24v ac the dc 'ground' by connecting it to the 5vdc ground, so the cable has common ground, 24v ac and 5v dc cables?

from a theoritical pov it seems OK as the outputs from the transformer and the 5v supply are all floating, but I am not a squiggly volts expert...