Minor electrical problem

Stan in Oly, WA

Well-known Member
I helped a friend add an outlet to one wall of a bedroom that had only one outlet on that wall. A plug-in outlet tester showed that that outlet was grounded, but when the outlet was removed from the junction box, there was no ground wire. The grounded type outlet had been wired between one of the neutral screws and the ground screw. We replaced that outlet with an ungrounded, two slot type so that there would be no mistake in the future about whether it was grounded. We got power for the new outlet from a different, grounded, source. My question is this, is there any way to determine that an outlet is not actually grounded when that has been done, other than removing it from the junction box and inspecting it visually?

Stan
 
Not unless you can see the wire going into it, and determine that it is 2 wire only. In that case a three prong can't be grounded properly. Some legacy systems were grounded through the BX steel spiral covering. And just because it has 2 with ground doesn't mean they actually hooked up the ground. Jim
 
You should/may be able to tell just by taking the plate off of it. Other than that, there is not a tester that I am aware of that will show it.
 
On occasion I've run across metal boxes that someone has attached the ground wire to the box instead of the outlet. I wonder if yours might be done like that. That would explain how it might be grounded when fully assembled.
 
Actually had to do this up at the folks place. They somehow lost neutral. Lights in one room would come on at half power. Luckily I had a couple hundred food roll of stranded wire on the truck. Just unwind a $tttload of wire and ground it to the lightnig rod wire out back. Take 5he wire and your digital meter and drag it through the house room by room. You should be able to find if you have a neutral or true ground pretty quick. You will get trace voltages. If you are having power problems then you need to hook that wire to 120v with a little Radio Shack fuse holder and a box of 1amp. Glass fuses. Be careful but it will work.
 
(quoted from post at 22:51:33 03/02/17) On occasion I've run across metal boxes that someone has attached the ground wire to the box instead of the outlet. I wonder if yours might be done like that. That would explain how it might be grounded when fully assembled.

In jurisdictions like the Chicago area, no romex is allowed by code. Everything is/was in conduit (emt or BMX). Bringing an older house up to code (3-prong grounded outlets) was done by attaching the ground wire from the outlet to the box which, in theory, is grounded through the conduit. I looked at a number of homes for sale in the Evanston area when my daughter moved there couple of years ago and they were all that way. Cheaper than pulling 3 new wires (H/N/G) through the conduit.
 
"My question is this, is there any way to determine that an outlet is not actually grounded when that has been done, other than removing it from the junction box and inspecting it visually?"

I would simply turn off the power and pull it out of the box just enough for a look see versus any instrument test, its sooooooooo easy to do.

If its the modern 3 wire convenience outlet branch circuit wiring system the conductors (possibly 12/2 w/Ground Romex) there will be a White Neutral, a Black Hot and a Bare/Green Equipment Grounding Conductor.

If its a metallic box it needs bonded to the Equipment Grounding Conductor,,,,,,,,,ALSO the Green grounding terminal (on a 3 wire grounded receptacle) on the receptacle needs wired to the Equipment Grounding Conductor.

NOTE if the metal box is grounded and even if the receptacles grounding terminal isn't attached as it should be, when the receptacle is mounted into the box there will be a connection, so the ground would show up on a tester but NOT if its removed out of the box. When you say there was no ground wire but a tester indicated the receptacle was grounded, it may have been a metal box was grounded so the receptacle got its ground due to the fact it was attached to the box.

NOTE some wiring systems (lighting) use armored cable where the outer metal case serves as the Equipment Grounding Conductor but I was NOT a fan of nor specified that use

Soooooooooooo if there are three correct wires into the box (Hot, Neutral, Ground) I would use a 3 wire receptacle but if there are ONLY TWO (Hot and Neutral) wires in the box, Id use an old style two wire receptacle. Don't forget to ground BOTH a metallic box PLUS the green grounding terminal on a 3 wire receptacle. Do not create a bootleg ground by attaching the Ground terminal to Neutral.

John T
 
After upgrading the electrical systems in several older homes and seeing all kinds of "work arounds" I would agree with John T, just remove the cover and look.
As an aside I have come to the conclusion that there is no real place to stop a branch circuit upgrade other than at the main panel. We all know that means 3 wire cable, 3 prong outlets and GFI were code requires them. A person never knows who might do something stupid in the future and look for somebody else to blame it on. Even putting it back as it was is not an excuse. When somebody asks me for help I tell them up front, if it doesn't meet current codes it will when I am am done or I aint touching it. (also gets me out of a lot of freebe work, LOL)
 
Stan in Oly,

If the box is not mettalic and has a conductive path to the panel ground, why not install a gfci outlet instead of the two prong?

I believe you can, as long as it's labelled NO EQUIPMENT GROUNDING conductor. At least the item plugged into that two prong would have GFCI protection.

D.
 
The tester showed ground because the cable is armored steel and attached at the point of entry grounded. Otherwise the tester would show no ground . If that is that case then a ground tsil from box threads could go to green screw on receptacle. If not then a GFI should absolulty be used . The two prong receptacle you have should go in garbage can.
 
A GFI is only used din the situation to provide protection due to lack of ground. The cure for no ground is GFI receptacle. Alternative run a ground back to panel would not be feasible.
 
It was a non-metallic box, supplied with power by a non-metallic 12/2 cable without ground. The outlet was a modern three prong type. A length of 12 gauge bare copper wire connected the neutral to the ground terminal on the outlet. John T called this a "bootleg ground". The tester showed the outlet to be "Correct". My question was whether there is any kind of tester which will not fooled by this "bootleg ground". John T advised turning off the power and removing each outlet from its junction box for a visual inspection. That's the exact thing I was asking if there's any way to avoid.

Stan
Plug in type circuit tester
 
"I would simply turn off the power and pull it out of the box just enough for a look see versus any instrument test, its sooooooooo easy to do."

Easy is a relative term. I find many jobs to be very easy until I start doing them, and a job that may be easy to do once stops being what I would describe as easy when it has to be done thirty or forty times. I would normally think of pulling an outlet out of the box just enough to visually inspect it to be a simple task, but I'll bet if I had a perfect memory, I could remember at least ten different ways that simple task has turned into a problem in my experience.

Stan
 
No tester will do that because it will always read the connection between the neutral and ground at the panel. If that connection is in the box [ illegally] the tester cannot detect that. In the case where there is no ground at the box and it is only fed by two wire then a GFI is the only protection without running wire.
 
I had to upgrade 27 sites in our RV park (long story)
Anyway they wanted a 4 wire system, hot/neutral/ground/equipment ground, I offered to put 2 ground rod at each site as we already had triplex in the ground, nope!
1000' feet of ditch :roll:
 
A person doesn't advance in the inspection or enforcement areas of government employment by being imaginative or flexible. Competence is frequently not a requirement either. (In fairness, I have to say that I've dealt with building and electrical inspectors who were excellent---knowledgeable, helpful, and reasonable.) My brother-in-law was once told by a county health inspector to make up the location of an old drain field on a plot plan for his application for a new septic system. My BIL asked the inspector, "Are you telling me that wrong information is preferable to no information?" The inspector said that it was.

Stan
 

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