I recently purchased a house built in 1950 & found there is no ground system (not even metal shielded cable although the b boxes are metal). The electrician who upgraded our main panel said that there few houses in this area (rural northern montana) which do have grounded electrical systems. I have replaced a few outlets w GFCI, but that would be expensive to refit the entire house (which is all set with 2-prong outlets except where GFCIs have replaced them). Is it possible to retrofit a ground plane? What approach would be most cost effective?

It is possible but not cost effective. If you put a gfci outlet at the first outlet for each circuit and then correctly connect the outlets downstream the downstream outlets will be protected.

there had darn well better be at least a house common ground through the cold water pipe... although code requires a ground rod bonded to the neutral at the panel, and a ground bonded to the neutral at the panel going to the opposite side of the house. that's usually the cold water pipe at the meter.

on confirming that, and bringing ground up to code if needed (and it probably will require a driven ground rod and some #6 wire), you could rewire from the service panel where you needed new grounded outlets etc.

where an appliance has a metal case and a grounded cord, there really should be a real-deal grounded service. see, the case could be electrified if there was an insulation failure. why get whacked and trip the GFI if you can blow the breaker and signal a serious issue in the first place.

This message has been edited. Last edited by: swschrad,