This seems to say it is.
I use the flexible hose with the metal wire coil. I have run it with that wire grounded and not grounded. No difference. I get a shock when I touch the hose either way. So I believe PVC can’t drain current to a wire. I have never had Z axis affected by it either. But that is mostly because I make sure the hose never touches the metal of the machine - especially the Z slider or motor.