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Everything has to be conduit by code. When i use my stop shock tester everything in the house shows no problems which is two wired. However, when those wires run from the panel box to the detached garage, it shows bad ground. When i use two other testers that doesnt contain bad ground, it shows correct. The new receptacles and wiring i checked a half dozen times to the electrical outlets which is wired 100 percent correctly. Also to note before changing receptacles, the old receptacles also showed bad ground. Why the discrepancy between the house and the detached garage? Thank you again in advance.

  • I'd presume it is measuring the potential between the ground and the neutral (similar to a GFCI).... assuming either your garage has its own path to ground or the ground to the house is high impedance, so differential or ground loop? – noybman Sep 2 '17 at 4:09
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    Are you absolutely sure that you understand that a ground rod in the outbuilding is not enough, and you must also connect a ground wire to the main house? (I'm fairly sure you do, just it can't be overlooked because that would give exactly this symptom.) – Harper Sep 2 '17 at 4:23
  • Also, all of these testers are basically magic 8-balls with their silly little sayings. At least a normal 3-light tester is a 3-light triangle and you can read it correctly if you learn. This Sperry tester defeats that, leaving very little of value to me. – Harper Sep 2 '17 at 5:24
  • Does the detached garage have its own sub panel ? Or is it a straight line feed from the house panel ? A sub panel will have its own grounding rod at the detached garage . Since they require conduit by code - do you have a ground connected to it ? – Ken Sep 2 '17 at 10:45
  • The wires (46 yrs ago) that comes from the house panel has no ground wire to the garage. Only the main house has a rod outside the main house as Harper which he is totally correct. Ken the wires go into a junction box (not a subpanel) where it feeds out to light switches and electrical outlets (again all conduit in garage). In short the garage isnt grounded from your explanations and if that is the case as well as most of my neighbors whose homes are identically built. Anyway, if i put a grounding rod outside of the garage and run it to the junction box would that help or what do you suggest? – larry pinsky Sep 3 '17 at 15:34

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