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I am going to be updating electrical outlets in my house, so today I checked them all with the 3 lamp tester. Only a few are properly grounded and others not. One outlet is showing strange behavior.

If washer is connected to the lower outlet, the upper shows proper grounding (lamps 2 & 3 are ON). But if I disconnect the washer and check again, only 2nd lamp is ON indicating no proper grounding. Is connecting the washer doing something funny with both receptacles?

Update:

  1. When the washer is connected to a GFCI outlet, it runs uninterrupted without tripping that outlet. I have tested that the GFCI outlet is working as expected (the reset test).
  2. I tested the original non-GFCI outlet in my question with a second 3 prong equipment (a grain mill) and now the receptacle tester illuminates only the middle lamp (i.e. no grounding) as expected.

So it looks like there is definitely some grounding fault with the washer but that doesn't stop it from working either on GFCI or non-GFCI outlets.

Update 2:

  1. It looks like my GFCI receptacle may be wired incorrectly. I can't get it to trip with gfci receptacle tester. In stead, when I press the tester switch, it lights up first and last lamps indicating that neutral and hot are reversed. I will post another update when I open up the outlet to check.
  • What are lamps 2 and 3 – hello moto Jun 9 at 4:17
  • Where are you on this planet? – ThreePhaseEel Jun 9 at 4:21
  • Sorry for not being explicit. Lamps on the receptacle tester. – cryptic0 Jun 9 at 4:24
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    Does the washer have a neutral-ground fault? – Harper Jun 9 at 4:36
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    "Open ground" doesn't mean a ground fault; it means you need to start opening up boxes. – Mazura Jun 9 at 21:53
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This feels like the washing machine has a ground fault, where there's a connection between neutral and earth somewhere. See Why does my laundry machine trip the GFCI when I plug it in?

If so, this is something you need to deal with, as it makes using your washing machine unsafe.

(In that case, when the tester checks for ground, power goes into the earth pin, up the earth pin on the washer, out the neutral pin on the washer, and back into the panel, which looks a lot like a real ground.)

You can also test with a different three-pin device connected, and see if you still get a fake earth reading.

EDIT: since you tested with a GFCI, and it works, I'll take another look with the new information.

When you plug in the washer, the 3rd light comes on. The usual meaning for the third light is that there's a voltage difference between hot to ground, which means the ground is going somewhere. While it's possible there's a grounding wire somewhere that you missed, another interesting possibility is that the surface the washing machine rests on is acting as a ground. This is somewhat dependent on the surface and the actual construction of the washing machine, but if the washer feet are metal, and it's resting on concrete, there might be enough conductivity to give a ground reading. In that case, your tester is giving a correct result. (But you should still run a real earth wire.)

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    You could use a long extension cord to plug the washer into a GFCI receptacle to test for a ground fault. – Jim Stewart Jun 9 at 11:17
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    You should note that not only is the washer faulty, but the missing ground should also be fixed. Probably obvious, but hey... – Jeffrey Jun 9 at 14:05
  • There is infinite resistance (reading of 1) between the GROUND and NEUTRAL/HOT plugs of the washer. Does that mean my washer is OK? I also checked both the outlets with multimeter and neither are properly grounded. – cryptic0 Jun 9 at 14:39
  • @JimStewart Is that safe to do? The cord clearly says not to use extension cord. – cryptic0 Jun 9 at 15:06
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    @cryptic0 if you use a heavy duty cable and only have the washer on long enough to see if it trips the GFCI you'll be OK. The danger is that if you use a light weight extension cord (think lamp cable) and run a full wash cycle you'll overheat the cable and have a fire hazard. Heavy duty cords are made with thicker wires to carry heavy draws; and for the test you only need the washer on briefly; because if there's an electrical fault the GFCI should promptly shut everything down. – Dan Neely Jun 9 at 15:25

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