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Grounding old 2-Prong Outlets: Adding Extra Grounding Cables Question

Grounding old 2-Prong Outlets: Adding Extra Grounding Cables Question


Old 12-05-05, 10:39 AM
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Join Date: Nov 2005
Posts: 34
Grounding old 2-Prong Outlets: Adding Extra Grounding Cables Question


I understand that there are different ways to add a grounding to the old 2-prong outlets. I want to upgrade our 2-prongs and decided, that I will do "the cleanest" solution and replace the 2-prong outlets with 3-prong outlets and add a separate #14 grounding cable to each receptacle. We have just a one-storied house an all cables are easy accessible through the crawl space. I want to daisy-chain the grounding cables in the crawl-space and hook the cables into a grounding rod. As I understood it, I have to connect this grounding rod with the main grounding from the distribution panel.

I am not clear about the layout of all the grounding cables; How many grounding cables max. should be daisy-chained and what would I daisy-chain them with? Is it o.k. to run e.g. 5x 14 AWG into one e.g. 10 AWG cable which goes to the new grounding rod? What does the Code say to that? How big of a cable would I need between the new grounding rod to the main grounding rod ... or can I just hook up all grounding cables directly to the main grounding?

Thanks for your opinions ... and if there is a better way to do that, I am open for alternatives!

P.S.: I read that many suggest to simply check if the 2-prong boxes are grounded. How can the metal box be grounded if there is no grounding cable????

P.P.S: What is the point in connecting the receptacle grounding with the main grounding?
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Old 12-05-05, 10:51 AM
Join Date: Sep 2003
Location: Central New York State
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You do not connect these extra wires to a ground rod. You connect them to the main panel. If your main panel is not properly grounded then you ground the main panel.

You will be much better off (if you are going to do all this work) to replace the cables completely.
A much easier alternative is to simply ground those receptacles that need to be grounded, leaving the other as ungrounded.
Old 12-05-05, 11:31 AM
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If you decide to rewire by pulling new cables you can add new circuits to better suit your needs. You could also add new receptacles to the layout for convenience.
Old 12-05-05, 02:04 PM
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If your house has BX and metal boxes you may have a ground through the metal jacket. If the house is wired with 2 wire Romex your SOL
Old 12-07-05, 10:27 AM
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Join Date: Nov 2005
Posts: 34
Thanks everybody!

Yes, at this point rewiring is probably the best choice. Those cables were laid in the 60s. (we just bought the house). Some of them are in a bad shape. I spent 2 hours in the crawlspace yesterday and made an inventory of the cabling.

The main service panel is the only thing which looks good. Other than that, there are a couple of open wires lying around, other cables were connected with duct tape. Man, how did they get away with that!? I'll do a serious cleanup and probably have a professional electrician to look over my shoulder. I did not touch anything, but the next time I go in the crawlspace, I will shut off the main power. :mask:

BTW: I found a grounding rod right next to the main service panel outside. It is correctly connected to the service entry which is fine. But it is also interconnected to a second grounding cable going to the water pipe; isn't that one too much?
Old 12-07-05, 10:55 AM
Join Date: Feb 2002
Location: port chester n y
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"One too much?"---No--- the NEC requires a "supplemental", or "secondary" Grounding Electrode in addition to the "Primary Grounding Electrode", which is the metallic water-service pipe,tubing

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