Ground wires in outlet boxes, lack of

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  #1  
Old 11-28-05, 02:05 PM
intheJC
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Ground wires in outlet boxes, lack of

Sorry in advance for the novel...

I have had to replace several items such as receptacles, light fixtures, etc. In doing this, the instructions always call for the line ground wire to be connected to the ground wire nut in the outlet box - same for the ground wire from the fixture. Several times, I have found that there is no ground wire coming into the box from the line. In these cases, I have attached the fixture ground wire to the ground nut in the box anyway. My question is, should there always be a ground wire coming into the box? If there is none; is this safe, and is there another way to ground the fixture?

An extension of this; I am about to replace a std 15 amp receptacle with a 15 amp GFCI, because the outlet is one I use to run extension cords out to the front of the house for Xmas lights (no GFCI on the exterior of the building). There is no ground wire in this particular box. Can I still install the GFCI, connecting a bare copper wire from the GFCI to the ground wire nut in the outlet box?
 
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Old 11-28-05, 02:10 PM
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Fifty years ago, we didn't use grounding wires. So if your house is fifty years old, then that explains it.

If your house is modern, then it may be grounded via metal conduit. Is you house wired with metal conduit rather than Romex cable? If the boxes are metal, you should connect any grounding wires to them.

Grounding is better than no grounding, but we all play the hand we're dealt, or pay big bucks for a new hand.

A GFCI functions perfectly with or without a grounding connection.
 
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Old 11-28-05, 02:20 PM
intheJC
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Thanks for the input. My building is actually 150 years old, in which I have a condo, so I am sure there is a blend of many styles in there. The boxes I have gotten to have all been metal, and the few times I have gone deep enough to see conduit, it has been metal, not Romex. Guess what I'll do is look for line ground wires and pull them into the box where/if I find them, and ground fixtures to the metal box when I don't find them. I'll go ahead with the GFCI, though. Thanks again.
 
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Old 11-28-05, 02:24 PM
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After you install the GFCI, use either a plug in type tester or a two wire tester and see if the ground is really a ground, or if it is nothing.
 
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Old 11-29-05, 01:33 PM
intheJC
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I have a very simple two prong tester. How can I use that to tell if the outlet is really grounded?
 
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Old 11-29-05, 01:42 PM
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The simplest way is to spend $8 at your home center on an outlet tester, the kind with three prongs to plug in and three lights on it.

If you have a simple $2 two-probe neon circuit tester, you can test between each slit and the grounding hole.
 
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Old 11-29-05, 01:59 PM
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Originally Posted by intheJC
Guess what I'll do is look for line ground wires and pull them into the box where/if I find them, and ground fixtures to the metal box when I don't find them.
Often, the metal pathway of the conduit itself can serve as the ground. A seperate ground wire is usually not required in an electrical system with continuous metallic conduit. Because of the age of your building, I'm sure you do have quite a mix in there. The conduit may provide an acceptable ground in some places and not in others. As the other posters have mentioned, a simple plugin style tester will tell you if your outlets are grounded.
 
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