Non grounded outlet says it’s grounded?

Discussion in 'Electrical and Wiring' started by demoso, Mar 6, 2019.

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  1. Mar 6, 2019 #1

    demoso

    demoso

    demoso

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    We had two cream outlets in our living room and my wife painted and wanted all white ones. They are the three pronged 15amp outlets. So I bought two and switched them out. The first outlet is controlled from a light switch so you can plug a lamp into it and shut it off and on with a switch. The second outlet is always on. Both outlets were wired exactly the same. One wire going to the left side and the other wire going to the right side. There is no ground wire on either of these outlets. When I tested the outlets with a tester that you plug into the outlet the outlet that is on the switch says there’s an open ground. Which I expect. The other outlet that is not on the switch says it’s wired correctly even though I know there is no ground wire going to the outlet. How is that possible? I do plan on correcting this if I can or have an electrician do it but I’m just curious how it’s possible and should I check the rest of my outlets in the house for this even though they all test out correctly? Just bought the house a few months ago.
     
  2. Mar 6, 2019 #2

    Snoonyb

    Snoonyb

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    You'll need to do some more investigation to determine if there could be a grnd.

    Was the switched receptionist. tested with the switch on or off?

    Are the boxes metal and/or are the elec. conductors run in metallic flex or conduit?

    Some old Rome had an 18ga. copper conductor that was bonded to the box with a spring clamp.
     
  3. Mar 6, 2019 #3

    demoso

    demoso

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    Yes the switched outlet was tested when switched off and the tester didn’t light up at all. No power to the outlet either. The boxes are metal but I’m not sure about the conduit.
     
  4. Mar 6, 2019 #4

    bud16415

    bud16415

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    The one box has to be grounded then. The outlet is picking up the ground where the screw connection is holding the outlet to the box. To test it pull the outlet again and carefully do your tester where the outlet is just held away from the box by the wires. Look in the back of the box and see if there is a ground screwed to the box.
     
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  5. Mar 6, 2019 #5

    WyrTwister

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    Exactly what I was going to suggest .

    If you put a 3 prong receptacle on a 2 wire circuit , it must be GFCI protected ( maybe , Arc Flash , now , if it is not grandfathered ) . Either by a GFCI receptacle or circuit breaker .

    With the receptacle hanging out of the wall by the wires , test hot to neutral , with a Volt Ohm Meter . Should read 120 VAC .

    If you have a metal wall box , now test from it to the hot . If it reads 120 VAC , the box is grounded . This will work for what you are doing .

    https://www.harborfreight.com/7-function-digital-multimeter-63604.html
    Wyr
    God bless
     
  6. Mar 11, 2019 #6

    demoso

    demoso

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  7. Mar 11, 2019 #7

    demoso

    demoso

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    I won’t get a chance to check the outlet for a little while but when I do if I determine the box is grounded then do I still need a GFCI outlet or is the outlet fine being grounded through the box?
     
  8. Mar 11, 2019 #8

    Snoonyb

    Snoonyb

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    If when Using a VOM, with the red lead on the hot side of the receptacle, and the black lead on the box, you read 12ov, the box is grounded.

    To ground the recep. you attach a 12ga. bare copper lead from the recep. ground screw to the box using a green ground screw.
     
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  9. Mar 12, 2019 #9

    afjes_2016

    afjes_2016

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    You should be able to use a self grounding receptacle like this as long as the box is grounded which you said the test reveals. Using this you won't have to use the jumper from the box to the receptacle.
     
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