I have just discovered this forum and the amount of useful information is remarkable! I've spend hours pouring over the posts. One of the best I've ever found.

My question is regarding the wiring in my home in Northern California that was built around 1959. It is wired exclusively with 2-conductor wiring (plastic insulation, paper-wrapped, outside black/silver fiber sheath) except for 220 circuits using 3-conductor. There are no safety ground wires running back to the 100A load center (Federal Pacific). However, this said, about 75% of the outlets (100% in kitchen, bathrooms) have a safety ground. This is done using a separate network of #14 bare copper that weaves itself through the walls and attic. This network is attached to the copper water plumbing at several different points under the sub-floor. It typically seems to be attached to the junction boxes by a couple of "wraps" around the nail (under the metal ear box ear) that holds the box to the stud.

My question is regarding the need to add additional circuits to my home, for example, to power a new set of garage outlets (there is only one outlet in the garage for the washing machine). What does the collective wisdom of this forum recommend so that as I began to discuss options with my local contractor, I will have a better understanding going in?

The old Federal Pacific box needs to be replaced, in my mind, since the discontinued breakers are very expensive. A local hardware store (Orchard Supply) carries a full selection but they can cost from $40-100 each. Can a new modern load center be installed with my present wiring system? The only circuits that would use the grounding bar, in this case, would be the newly installed circuits with NM-B with ground wire.

The last interesting observation in this regard is that I had a central air conditioner installed 5 years ago. The compressor is of course 220 2-phase and the contractor installed it with standard 2-conductor Romex, using the bare safety wire as the common, no safety ground. The bare wire is wrapped in tape where exposed on each end inside the boxes. The post-work inspection was signed off. Does this fall under some sort of grandfather clause?

Thanks in advance for your comments, advice, and/or guidance,

C. Brent