I have a home built in 1966 that uses knob & tube (yes, the date is not a typo) and the panel of which uses fuses. (Yes, it’s weird – perhaps the electrical sub had stuff they needed to use up). And they actually ran grounding conductors to the receptacles. Sounds incredibly labor intensive, but that’s what I’ve got. In any event, I noticed that the number of grounding conductors in the panel do not match the number of grounded conductors. (Each circuit has a mix of both lighting and receptcles). A relative who is a licensed master electrician (whose residential work I have seen and which would qualify for any “wall of pride”) explained that this is because, in using k&t, they “looped” the grounding conductors, essentially allowing one grounding conductor to serve more than one branch circuit because the grounding conductors do not normally carry current. Is this possible, or just loopy? I’m going to be selling the house in the near future, and want to pre-emptively address electrical issues. Selling the home with k&t and a fuse panel will be hard enough as it is.
The grounding situation you describe is 100% legal. The date of your home and the fact that you have K&T suggests that you may be in the San Francisco Bay or SoCal area? Thermoplastic K&T was installed into the early 70’s in areas where organized labor had a strong influence on local rules and customs, since it was labor intensive.
Marc try Ohio its posted
Is there a name for this type of setup? How would I respond to an inspector that calls this out as inadequate or improper grounding?
Michael,
Basically it is quite ODD to have K & T in a house of that vintage…to be honest with you sounds like an old retired electrician did it who was at the end of his “Work” cycle ( life )
The idea of sharing a " Grounded " conductor in old K & T homes was sometimes called a " Common Neutral " installation where the systems ungrounded conductors handled the circuits and many rooms shared the connection to the “Grounded” conductor…the problems with that in todays world is overloading the neutral as it was not designed to carry things being placed on the circuits today.
Chances are what will really limit you is the so few receptacles probably in the rooms itself…which is what leads homeowners to using the old power taps or power strips and overloading a circuit to begin with…good news is that a fuse will probably blow faster…
As for the setup of looping a single " EGC" or Equipment Grounding Conductor around the entire house…well I can’t truly say I would ever do that but as long as the looping is terminated properly, and the EGC is sized properly for the circuits in question it is doable I guess…again I would not do it simply because the concept of having a properly done bonding grid ( which is really what the EGC is…should be EBC in my opinion is important to operation of the OCPD…and in a loop layout as you describe one failure at a connection removed the entire systems ability…
Can they fail…YEP I did a service call on one at a PrimeTime outlet just yesterday where a simple connection in the ceiling failed…granted it was a “grounded” conductor and not a grounding conductor…but the wirenut had failed and it gave them an open neutral setup and with a loss of the neutral we know what happens…