I was just in a older (about 30-40 years) house that I think has metal framing. It appears that the wiring was 2 conductor NM. A ground wire has been run between the box and the device. It seems like they were using the framing to achieve the ground connection. A plug-in checker shows the devices are wired properly. I don't think that this is the way it should be, but don't have enough info to make an informed decision. What options should I tell the owner are available?
Jim, some of the old houses I deal with, use a small(16 gauge?) bare copper wire that runs throughout the house, "connected" to the boxes by wrapping several turns around a nail that attaches the box to the stud. The wire would terminate at a water pipe with a strap. The wire is tee tapped, by wrapping the tap around the main wire and soldering, just like knob and tube wiring. Sometimes it's just the kitchen and bath that have the wire.
some of the old houses I deal with, use a small(16 gauge?) bare copper wire that runs throughout the house, "connected" to the boxes by wrapping several turns around a nail that attaches the box to the stud
I've seen that too, usually for Kitchens. Never seen Copper though, the ones I've seen seem to be Aluminum. They sometimes go from each device box up to the attic and are twisted together, or joined by some other questionable means. Many times these wires are cut or broken and not repaired simply because no one knows what they are.
I had some pictures around, but can't seem to locate them right now.
Is there no ground wire at all? All the metal boxes in my house were grounded with a bare #12 that was daisy chained from the back of one box to the back of another, then to ground in the service. It wasn't run with anything else,just by itself. It apparently was Code compliant at the time ('58). I've seen lots done this way.