Have a troubleshoot to do tomorrow in a home that is a hybrid in that there are some circuits from the service panel that have been added over the years and are grounded but there are still several KT circuits. still in use. Nearly all the outlets that I saw were replaced with 3 wire outlets for convenience which of course isnt cool including many on KT circuits. Problem is when comcast tries to install a cable upstairs in one room when they plug in thier cable they get big time sparks. Last time I had one of these it turned out to be H/N swapped on a KT and a bootleg ground picking up voltage. At least thats what I recollect. Any thoughts?