While testing my outlets with a circuit tester, two of them indicated an "open ground" condition; the other outlets registered normal. The circuit is 20 amps with four duplex receptacles, one combination switch outlet, and one dimmer switch. These outlets are on the main floor of the house(dining room). House was built in 1959 and the electrical wires are black, white, and bare cooper. The "open-grounded" outlets are middle-of-the-run.

I opened every up every single outlet box and switch plate and checked for proper grounding connections(to both box and receptacles, pigtailed)and every one of them were properly wired.

I guess somewhere in the house is a ground wire that is not connected that these two particular outlets were tapped off from?
Had a similar problem with another circuit; however I managed to find the culprit-an unconnected ground wire in a wall switch in an adjacent room!

I am concerned that this "open ground" is a safety problem, although we have lived in this house for 13 years now.
Unfortunately, the basement ceiling is newly finished, so short of tearing apart the sheetrock, not really sure how much more I can do to try to find this problem-already spent days to no avail! (Especially enjoyed crawling around in a hot attic!)

Thanks for any suggestions, advice, and alternative solutions.
Also, as far as the use of these particular outlets, one is used for a 13" TV, and the other one has a nite light plugged into it.

 

I'm guessing that neither the TV nor the night-light even has a grounding prong on the plug. If you can find and correct it, by all means do so, but if you cannot, I wouldn't lose any sleep over it.

 

Thank you, John for your quick reply.

Besides the TV and night-light, which by the way-you are absolutely correct-there are no grounding plugs-the heaviest item ever to be plugged into these particular outlets is either a vacuum cleaner or a carpet cleaner, which do have grounding plugs. Would this pose a problem?

Also,would installing GFCI outlets be a viable option in this instance?

Thanks for putting our minds at ease-I've had somone tell me that this situation with the "open grounds" on these two outlets is dangerous and poses a fire hazard!

 

There are still millions of homes in the U.S. with no grounded outlets. Of course, ungrounded outlets are not as safe as grounded ones. But cars without antilock brakes are not as safe as cars with them, but we're not yet junking all the cars without them.

Grounding is mostly for protection of people and equipment. The lack of grounding is not a fire hazard. However, old wiring may (or may not) be a fire hazard for other reasons.

Yes, GFCI would add considerably to personal safety. Code does not allow three-hole ungrounded receptacles without GFCI protection.

 

Do I stiil attach a pigtail from the grounding screw on the GFCI receptacle to the bare grounding wires in the box and then pigtail to the metal outlet box screw?

Thank you.

 

If the grounding wire is not connected all the way back to the panel, then don't connect it anywhere in the outlet box.

 

I would go back and check every ground connection in the run. There should be no reason to 'pull' a ground from anywhere if you have one in the cable. A visual examination may not reveal a bad wire nut joint. Pull gently on each wire and see if one is comes out. It is not a pressing safety problem, but if the ground wire is in the cable you should be able to figure out where it became disconnected. If all else fails, I would ohm out the ground wires between receps and see if there is a break.

 

The only concern I would have is that the open ground could be indicative of a damaged cable which could indeed be a fire waiting to happen.
--
Tom

 

That's the confusing part; I opened up every box, retightened and taped all wires nuts, and in some cases, started from scratch as far as connecting the grounds to the outlet and box, yet only two outlets on the run are showing this condition-the rest are registering normal.

The outlets are middle-of the-run, unfortunately I cannot trace the lines since it seems one is coming up and the other line is going down between floors to basement(finished ceiling). And no, nothing down there is on this circuit.

I think I will follow John's advice and go with the GFCI's....losing too much sleep over this!

 

Did you check any lighting fixtures on the same circuit? There are grounds in them as well.

 

(Thinking out loud)

If the two recepts are in the middle of the run and the devices next to them are grounded would it not indicate that the problem might be with those two devices themselves?Maybe the yoke came apart?

It maybe a wize idea to take voltage readings at the wires themselves to see if there is a reading to ground indicating that the recepts are at fault.

 

John:

Since the ground for these two receptacles are "open", this would mean that the grounding wires are definitely not connected all the way back to the panel (since they somehow/somewhere became disconnected)-so then, do not connect the ground wires to the proposed GFCI receptacles,-correct?

Assuming your answer is "yes", out of curiosity, what would be the problem if the grounds to the GFCI's were connected, in this instance?

Thanks.

 

I don't know if the grounding has become disconnected, or was never present in the first place.

Code prohibits connecting a wire to a grounding screw that isn't a valid grounding wire (although I cannot cite a reference off the top of my head -- anybody else?). I know of no particular problem other than it might be misleading (but of course the code doesn't explain itself, so we are left to guessing at the rationale).

 

Notice that the code specifically forbids interconnecting the grounding terminals of the GFCI and any receptacles that is supplies.
--
Tom

 

The circuit you have described is classified as an Small-Appliance circuit. You state that this circuit includes "A combination switch outlet" and "one dimmer switch".

A dimming-switch connected to a Small-Appliance circuit is baffling--what purpose does this dimming-switch serve?

Is the "combination switch outlet" a receptacle outlet connected to a wall-switch?

A certain type of cable inter-connects the outlets, usualy a 12/2 cable for 20-amp appliance-circuits. Does this cable consist of a Black wire, a White wire, and a bare, un-insulated Grounding wire?

 

Anybody know in which year's code the dining room receptacles became small appliance circuits? grumpy's circuit probably violates today's code, but we don't know when grumpy's house was built.

 

The house was built in 1959-1960.

The combination switch-outlet and dimmer switch is located in one box in the kitchen. The combo controls the ceiling fan, the outlet is hot.
The dimmer controls high hats. The ceiling fan switch is on a separate circuit. The hot outlet and dimmer are on the same circuit as the open ground outlets. However, this hot outlet registers normal for grounding.

All wires on this circuit on 12/2- black, white, and bare ground.

 

I apologize if I was not clear in my original post.

In the dining room, there are three outlets: two with open grounds(on opposite side of kitchen wall) and a third outlet which registers normal on the opposite side of the dining room wall.

The combo switch/hot outlet and dimmer switch controls a ceiling fanand high hats in the kitchen, which is located next to the dining room.

 

Please know that an "outlet" is any point where the Branch-circuit conductors are acessible for connections, the usual connection-point beng an "outlet-box".

To be more specific requires describing what is connected at the outlet box, such as "switch-outlet", "fixture-outlet", "receptacle-outlet". You mention an outlet that is best described as a "combination switch and receptacle outlet".

Obviously, describing exactly what is connected at the outlets helps in understanding the wiring connections.

You mention 3 dining-room receptacle-outlets ,and as best you know, 2 of the 3 are un-grounded. If the 3 are inter-connected, I suggest you determine how they are inter-connected, including locating the receptacle outlet-box that contains the "Feed-In" cable. Either the box with the "Feed-In" cable has 2 "Feed-Out" cables to the other 2 ROB's or 1 "Feed-Out" cable to the other 2 ROB's. An Open Ground-connection at the "Feed-In" ROB will result in the problem you describe.

Good Luck & Enjoy the Experience!!!

 

Only two out of the three outlets are interconnected.

Following John's advice, I decided to install a GFCI outlet. I turned the power off, disconnected the wires from both of these (middle-of the run) outlets; each metal box has two cables(12/2).

Turned the power back on, used a current tester to determine which was the feed in cable, turned power off, then installed the GFCI in this outlet connecting the feed in cable to the line terminals and the second cable to the load terminal. Did not connect the ground wires to the GFCI. Reconnected the cables in the second outlet, also did not connect the ground wires to the outlet. Tripped the test button on the GFCI to confirm that power was shut on both outlets.

So, after this exercise, I now know which is the feed in cable. However, I have already checked these boxes-I disconnected and reconnected the ground wires in both boxes by connecting(with a wire nut) the two bare ground wires with a pigtail to the metal box screw, and a second pigtail to the outlets' green grounding terminal. The ground connections were made by first twisting them together clockwise with linesman's pliers, then connecting them with green grounding wire nuts.

I have checked the service panel for this circuit and all ground wires are tightly connected to the neutral bus bar.

If this cable is coming up from the basement, then I cannot fully trace it since the ceiling is finished; I suspect the problem probably is indeed somewhere in the basement ceiling?

 

Just a small point of terminology, but I do not believe there is such thing as a "switch outlet". An outlet is not defined as any place where the conductors are accessible for connections, but rather a place from where power is taken. Since a switch uses no power, it isn't really an "outlet".

 

"A place from where power is taken (connected)" is not the same as "A place from where power is CONSUMED."