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?

Thanks,
Jim

first off~ this may have been compliant to the '63 nec....

secondly, there are newly marketed goodies to enhance the safety of older wiring, such as AFCI's

btw~ i would be very careful to offer anything more than 'enhancement' with these...

I'm not a construction expert, but metal framing on a 30-40 year old house seems unusual.
Maybe the boxes are grounded but you can't see it. From behind?

I would be very concerned if the framing of the house is used as an equipment grounding conductor...

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.

Using the structural steel, or a grounding conductor that is not run with the phase conductors may not ensure that the ground fault current path is effective.

250.4(A)(5) Effective Ground-Fault Current Path. requires this path to be effective, therefore that would not be a proper method.

I know that the code permits a grounding conductor to be run to the nearest equipment grounding conductor, 250.130(C), but I say this is asking for trouble.

Pierre

Stamcon,

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.

Bill

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.

Here's a Photo sent to me by Joe Tedesco showing a Ground wrapped around a nail:

Look at the nail going through the lower portion of the gem box.

Pierre

That's why the boxes have holes in the side.

P. S. Seriously, would that wire wrapped like that ever have been code compliant?

[This message has been edited by ThinkGood (edited 11-26-2003).]

"314.23(B)(1) Nails and Screws. Nails and screws, where used as a fastening means, shall be attached by using brackets on the outside of the enclosure, or they shall pass through the interior within 6 mm (1/4 in.) of the back or ends of the enclosure."

I'm going to take credit for the picture above. It is a common 60's vintage wiring method here in the SF Bay Area. Joe Tedesco calls it "Boston Backwrap" so you can see it shows up all over the country.

Another odd grounding method I've run into is splicing equipment grounds on the outside of the electrical box. This was a requirement from the building official in Alameda California. Apparently, a great many electricians received their trainin in Alameda and this practice shows up to this day.

Outer Limits Grounding

Check out the device. I sure don't see these on a regular basis.
125/250-15/20 make-your-own-but-don't-wanna-ground...S

Yes, I saw the ungrounded double 'T' receptacle and thought - why did they bother?

BTW, how long ago were these duplex configurations banned?