Adding Ground to 1942 House Wiring, have question?

Question

I am trying to change out my 2 prong outlets out with modern 3 prong outlets. I have modern breakers, and some of the electrical was replaced before I bought my house. Most of it is still original. At some point someone replaced some of the 2 prong outlets with 3 prong ones, but didn't hook up the ground.

My plan is this:

Run ground wires from the galvinized steel plumbing to each of the steel flex counduits that all the original wire runs through. I can then ground the outlets to the steel outlet boxes.

My question is: Does this meet NEC? I have some 14 gauge wire with green insulation that would work, but it is stranded. Does stranded wire meet NEC for home wiring?

Thanks for any help that you can give me!

Answer 1

MC cable is approved for grounding. But it has to be a metal to metal connection. Your receptacle box must be metal for the MC cable housing to be effective. The tiny bond wire in old MC is not approved for an equipment grounding conductor.

Everyone above talks the Code game, but where are the references..???

Sizing equipment grounds..Article 250-122
Receptacle grounding methods..Article 406

Answer 2

No it doesn't meet NEC. Fist what you've got is MC cable. that steel housing is the ground. and should run continously from the panel to the boxes for the recepltacles and switches. Gounding stuff by attaching a wire to the plumbing pipes has not been code for at least twenty years. If the orginal wiring is still in good shape and replcing it is not an option, then the solution is to replace the current two prong receptacles with GFI receptacles. The reason for this is that a GFI without a ground wire will still behave as though it is grounded, and will provide the protection required.
Be aware that GFI receptacles do not work will with most household appliances such as a fridge or dishwasher anything with a moter. If you are intending to change out receptacles where you will have electronics pluged into them, then you should really consider replacing the wiring. Because if you ground to the pipes (a poor ground) you'll have interfence that may affect the funtioning of your equipment. And while a ungounded GFI will meet code and perform as thought it is grounded, it will also cause a bit of interfernce.

Current code requires two ground rods, 8 feet in lenght driven into the ground 6 feet apart and a continuious ground wire run from one to the other, then to the meter can, then to the panel.
It might be a good idea to pay an electricain to come out and have a look. As part of it's been done hard to say what condition your wiring is really in.

Answer 3

The NEC allows (3-prong) GFCI outlets to be installed on ungrounded wiring.
If the "steel flex conduit" you are refering to is type AC cable and properly installed, then it could already be grounded. Type AC was acceptable as a grounding conductor. At each outlet box attach a bond wire from a green ground screw in the box to your outlet's ground screw. You'll find that solid wire is easier to work with; stranded wire will need a crimp-on terminator to work with most device terminal screws.

Answer 4

The flex conduit should already be grounded to breaker box by physical connections. With the conduit grounded, the receptacles will be grounded when the attaching screws are put in. Stranded wire will suffice, but solid wire is preferable for house wiring. This will meet NEC Standards, but check w/ electrical code for your community - it varies.

Answer 5

Tony RB has it right. But he wrote a damn book. Just get a new 14-2 with ground from your furnace to your panel. Wire the ground wire and neutral wire into the neutral bar. On a side note. It wouldn't hurt to put ground rods down. Code requires (2) 8' in length, all the way down, six foot apart, and connected to a number #6 AWG copper. This should go back to the neutral bar as well.

Answer 6

If the original wiring dates back to 1942 and there have been changes since, you would be wise to have it checked out by a qualified electrician. There are 3 issues here - safety, compliance with home insurance requirements and the local building code and any utility regulatory requirements. I would not have thought stranded wire suitable for domestic wiring.

Answer 7

Have ground to earth, ground to panel, ground to outlets. No worries. Anything else.....worries. Stranded wire is iffy as the full amperage can not be determined. Try to use solid conducters.

Answer 8

I don't believe you can use the conduit as a path to ground. You can check on NEC requirements at http://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asp for free.