Hal, I have seen places around here with original K&T, (TW plastic wire insulation, in colors even) installed straight up to the mid 60's. With original permits on the building/in the panel for proof. Many, if any grounds, were to the nearest cold water. It would seem a few guys back then stuck to thier antiquated wire system until they retired. (Like old dogs and new tricks.) Another real shocker, is that you'll have occassion to see 3-wire circuits in some of the early to mid 60's houses in K&T as well - SCARY! Something to watch for when doing panel changes here.... (I usually reduce the ciruit load in re-models by re-doing the plugs, and put all of them on the same phase, and two wire circuits. If i can....)
