Also, because of the way in which this type of surge protector connects , it is NOT possible for it to lift the ground like the OP has measured. It has nothing to do with ground.
It might be possible the electrician did something while installing it, or more likely, that something has gone bad independently of this. The way this works is that the neutral and ground may only tie together at 1 point in the entire home. So, it could be a disconnected ground or neutral anywhere from the listening room back to the service entrance.
Best,
E
It might be possible the electrician did something while installing it, or more likely, that something has gone bad independently of this. The way this works is that the neutral and ground may only tie together at 1 point in the entire home. So, it could be a disconnected ground or neutral anywhere from the listening room back to the service entrance.
Best,
E