DMM set in AC V and one of If its probe on ground the other on N (neutral) gives ~21V (unstable read ~ 7-33V) instead of 0V, how can there's some electric potential here, is it always AC or a chance being DC ?
while AI chat hints:

1. Stray Voltage
2. Grounding Issues
3. Imbalance in the Circuit
4. imperfect MM itself

Help elaborate it crystal clear

 

Most modern meters are high impedance devices, They will react to many stray currents that may be present. you need to place a low resistance, 1k e.g. , across the leads a see if the signal is sustained.

 

If you are going between the safety ground wire and neutral, then is sounds like the neutral and ground are not connected together at the breaker box as they should be.

 

Phantom voltages exist, for one reason or another.
A DMM with a LoZ range is needed to know it they might be dangerous or a real problem.

 

If you are going between the safety ground wire and neutral, then is sounds like the neutral and ground are not connected together at the breaker box as they should be.

That would depend on what year the house was wired and local building dept codes and country.
Mine was on the 2017 electrical code but the neutral and ground only connect at the service pole, a hundred feet from the house.

 

To check if there is indeed a connection, connect a 9V battery in series with an LED and a 1kΩ resistor between the neutral and ground, and see if the LED lights.

 

I have a similar situation at my house and I chalk it up to the Neutral and Ground being tied together at the utility pole that has the transformer. Been in the house over 15 years and so far, no problem.

 

Been in the house over 15 years and so far, no problem.

I have been in this house 22 years and I am getting old and forgetful. I think it is my wiring.

 

I think it is my wiring.

Either that or the gates connected by the wiring.