Another Outlet Question

[thenewguy]

Thanks to those who helped me earlier. A few outlets in my new condo do not have ground wires (most do).

I've run into another odd outlet and have a question.

Outlet is in kitchen next to sink. I want to put in a GFI. I take the old outlet out and it has no ground, 2 black wires and 1 white wire. Which is odd because my circuit tester said it had a properly functioning ground. The screw for the old outlet is very long and it's possible it is touching a copper wire that is back there (this copper wire is where the ground wires in the outlets that have them are connected).

I put the old outlet back in and stepped away from this outlet to think the problem out. I imagine that if I use the same long screws I should still touch the copper wire in the back and have a functioning ground. But will a GFI work without the second white wire?

Just a tad confused.

On the upside I've only got a couple more outlets/jacks to worry about before I'm finished. All that's left then is a sconce and a chandelier and then it's time to move furniture in.

 

[user 4883]

You'll have to check this to verify but, I think you have a dual circuit outlet w/a shared neutral. Check the old outlet to see if you have continuity between the two hot lugs (I suspect not). If you do; I'm temporarily stumped.
Also, coincidental contact is not proper for grounding. I'm interpreting that you have metal outlet boxes and there is a ground screw in the back of the box? In any case, you'll want to pigtail that ground wire and attach it to the outlet ground. If you have a dual circuit outlet, the you simply abandon one of the black wires and use the remaining to install the GFI. If you have any other GFI's in the home, you may want to see if the sink outlet isn't already GFI protected.

 

[thenewguy]

You'll have to check this to verify but, I think you have a dual circuit outlet w/a shared neutral. Check the old outlet to see if you have continuity between the two hot lugs (I suspect not). If you do; I'm temporarily stumped.
Also, coincidental contact is not proper for grounding. I'm interpreting that you have metal outlet boxes and there is a ground screw in the back of the box? In any case, you'll want to pigtail that ground wire and attach it to the outlet ground. If you have a dual circuit outlet, the you simply abandon one of the black wires and use the remaining to install the GFI. If you have any other GFI's in the home, you may want to see if the sink outlet isn't already GFI protected.

Thanks for the quick reply. I'll check to see if I have continuity b/w the two hots. Can I use my standard circuit tester or do I need to measure the volt difference between the two?

I agree coincidental contact (or even intentional contact via using a long screw) is awful. It's not a ground screw at the back of a metal box, rather, it's a copper wire that has a metal clip. This is common to the other outlets save for the fact that they have green ground wires coming out of them and this one does not. Next trip to the store and I'll buy a groun wire to connect to the copper wire in the back.

There are no other GFIs in the condo save for the ones I've installed.

I'll try abandoning the other black and cap it and see how that works.

 

[user 4883]

With the outlet uninstalled (thus no voltage to check), check continuity between the two lugs on the hot side of the outlet. You'll need a multi/volt-meter for this task.

Optionally, you can check voltage from neutral to hot on each of the hots and verify that way. If it's just a standard duplex outlet, you should see 120VAC on each hot to neutral and 240VAC between the two hots.

 

[handyguys]

If its a dual circuit with a shared neutral you can just look to verify.

The two black wires connect to one side I presume.

between the screw terminals on the hot side (where the black wires are) you will see a little metal bridge connecting (or not connecting) the two screws together. if it is a dual circuit the bridge will be missing, if its just passing a circuit through the bridge will be in place.

Dual circuit could be because half the outlet is on a switch or it could be two actual circuits. No ideas, off the top of my head, where the other white wire is unless someone made a x/3 wire with two blacks and a white.

 

[triple D]

I'm guessing there are white wires tailed down to one in the back of box. And further probably a red and red, or red and black tied together hiding in back of box. In any case if the right side of outlet is intact as mentioned in previous threads, Just put both blacks under power screw and the one white under other. And the new ground tail you mentioned from box to gfi. Was I of any help earlier on your switched outlet that would'nt switch after you changed it? Was the red wire hot? Sorry just wondering, always best of luck...