It seems my existing bath fan switch's ground wire is not really grounded. Probably because the one floor house is too old from the 1950s. I am planning to go to attic to have a look at what is going on there. The receptacles in the bathroom are grounded properly.

My questions are the following:

1. Can I connect the fan switch's ground wire to the bathroom receptacles' ground wire on the attic if they are two different branches directly from control panel?

2. More generally, can I connect any two branches ground wires together in the middle of the house and then have one of branches' ground wire grounded on the control panel?

3. Can I ground the old wiring to the cast iron vent pipe on the attic and this is considered grounded properly?

4. when I check the voltage between the hot and ground wire, the value is not around 120V. It is about 65V. Is this the indicator that the ground wire is not really grounded? The neutral -hot is 120V.

Thanks,

 

Are you sure of that ?

You definitely can't pick up a ground off any nearby pipes. I'm not even sure if it's to code to pick up a ground from a nearby grounded circuit. Typically a ground wire would need to be run back to the panel. If you were going to do that you could change the entire cable.

 

I have a tool to check if a receptacle is properly grounded based on which lights are on on that tool.

 

found this: https://diy.stackexchange.com/questi...ferent-circuit

 

I have seen the neutral wire tied to the receptacle ground tab.
The tester will show normal.... or grounded.... when in reality it is not.

 

really? then I will use meter to verify the tester.