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Electrical Outlet Tester


wingfoot
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Has anyone had their electrical outlet tester have all 3 lights, (2 yellows and a red) light up at the same time? What kind of wiring configuration would cause that? Is it dangerous? Any help would be appreciated.

ps. I did write it up as a wiring problem and to have an electrician evaluate and repair.

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Well...according to my 3 light tester the red would only come on if you had a hot/grnd or a hot/neut reversal. Why all three would come on is a mystery, but I suspect it's not good. Assuming your tester works fine in other outlets, then yes, I'd say the outlet is in some type of dangerous condition...just don't know exactly what. Report what your tester did and call for repair.

after a little more thought....how about reverse polarity and a bootleg ground to the now hot neutral terminal? It's the only combo I can come up with that wouldn't trip the breaker.

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Originally posted by wingfoot

Has anyone had their electrical outlet tester have all 3 lights, (2 yellows and a red) light up at the same time? What kind of wiring configuration would cause that? Is it dangerous? Any help would be appreciated.

ps. I did write it up as a wiring problem and to have an electrician evaluate and repair.

Yes. It's happened to me three times. In every case, the receptacle was wired with 240v. I just checked again with my GB 3-light tester. When you apply power to both flat prongs, all three lights light up.

When you get an anomalous reading like this, you should re-test the receptacle with something else, preferably a multi tester, to find out what's really going on.

BTW, false grounds do not make the three light tester glow dimly. However, partial voltage does. You'll often find this on switched receptacles where the switch is in the "off" position -- a little voltage, say 50 volts, can leak through a bad switch.

- Jim Katen, Oregon

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Originally posted by Jim Katen

Yes. It's happened to me three times. In every case, the receptacle was wired with 240v. I just checked again with my GB 3-light tester. When you apply power to both flat prongs, all three lights light up.

When you get an anomalous reading like this, you should re-test the receptacle with something else, preferably a multi tester, to find out what's really going on.

BTW, false grounds do not make the three light tester glow dimly. However, partial voltage does. You'll often find this on switched receptacles where the switch is in the "off" position -- a little voltage, say 50 volts, can leak through a bad switch.

- Jim Katen, Oregon

240V on a 120V style outlet?

Would someone do this to avoid running a new outlet for a 240V room a/c? Then install a 120V style plug on the a/c?

I've never seen this and just trying to imagine why.

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I too have seen the dim light on a tester, and as Jim said it's almost always a switched outlet. I call for the switch to be replaced.

Your conclusion of the three light result is interesting and seems to makes sense. I guess most appliances simply would not work plugged into it? Or could it be far worse? It doesn't sound good at any rate.

And, How would you technically call out that condition? "Hot Neutral"?

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I had the lights show up dim the other day and I had time to break out my multi meter and I had a reading of 85 volts. I had seen that a few times before but never took the time to check it out, now I know.

I really wish I would have used my multimeter that day to see what reading I got with all three lights lit up. It is really bugging me.

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Originally posted by Terence McCann

240V on a 120V style outlet?

Would someone do this to avoid running a new outlet for a 240V room a/c? Then install a 120V style plug on the a/c?

I've never seen this and just trying to imagine why.

First one was outdoors on the third story back porch of a 6-plex. The receptacle was next to a porch light, about 7 feet off the porch floor. I have no idea why it was wired that way. No one else knew either. The resident had never plugged anything in there.

Second one was, just as you guessed, for a 240v ac unit. The homeowner ran the circuit himself, but didn't want to bother buying a special receptacle. It was easier to use what he had on hand. He was fully aware of the danger and had even warned his wife never to plug her vacuum cleaner into that receptacle. This one clearly comes under the heading of "stupidity" rather than "ignorance."

The third one was originally a multi-wire circuit that served the two halves of a duplex. The homeowner replaced the receptacle and didn't understand that he had to break the tabs. He'd connected the red & black wires to the receptacle lugs and neatly coiled the white wire and tucked it into the back of the box. Result - 240v on a 120v receptacle. I attribute this one to "ignorance" rather than "stupidity."

These are probably good illustrations of why it's a good idea to have an electrician do even the simplest home wiring.

- Jim Katen, Oregon

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Originally posted by mgbinspect

. . . I guess most appliances simply would not work plugged into it? Or could it be far worse? It doesn't sound good at any rate.

And, How would you technically call out that condition? "Hot Neutral"?

Incandescent lights plugged into it would burn really brightly, motors would run really fast . . . for a short time.

Electronic items would probably be destroyed. I'm not sure what would happen to things that had power transformers attached.

I'll mess with it and get back to you. . .

- Jim Katen, Oregon

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Originally posted by Jim Katen

I'm not sure what would happen to things that had power transformers attached.

I'll mess with it and get back to you. . .

- Jim Katen, Oregon

If it were a step down transformer, say a 120v to 24v, I would hazard a guess the secondary would be 48v.

In other related news there was a small brown out noted in Oregon.

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  • 2 weeks later...

Okay, I've got another wierd reading to bounce off of the peanut gallery. Some outlets I tested today read "open ground" (center light only) until I tried the GFCI test button; then it shifted over to red light only while the button was down (no reading for that on the chart). Anyone know what the heck that means? [:-boggled

Brian G.

Light-Headed [:-paperba

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Brian,

As is obvious from previous posts, I'm pretty challenged with advanced electrical, but I wonder if that indicates anything significant? My only reason for thinking that is that when you put such a tester in an outlet to test for the presence of GFCI protection, if it is not protected, doesn't the tester indicate "reversed polarity" while the button is depressed? In other words, could the indicator always render a false reading while the button is depressed?

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Brian, look at the wiring diagram I posted on the other thread. I think the red light would come on if you press the button and the outlet is ungrounded, power shunted through the red light to neutral instead of ground. I'm not sure why the other light would go out. I am going to re-post the diagram with the rest of the resistors indicated, that may answer it.

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  • 2 weeks later...

This morning I dropped my outlet tester in the street and it broke. So, I broke open a new one and there was an 800 number so for jollies I called it and asked about the 3 light scenario.

The tech said the reason they don't include it in the legend is because it can indicate multiple problems.

The most common was Jim's scenario, two hot leads (over 120)

He also said it can indicare a poor ground???

Those are the two most common indications.

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I never even thought about calling the manufacturer about the 3 lights. Thanks for the info. I guess the next time I see it I'm going to take the time and test it with my meter and see what I get and post it here. If anyone else sees all 3 lights, light up on their pocket tester, could you post it here if you've put a meter on it?

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Originally posted by mgbinspect

. . . So, I broke open a new one and there was an 800 number so for jollies I called it and asked about the 3 light scenario. . .

I'm impressed that he took time out from his busy schedule of cranking these thing out in his garage to talk to you.

- Jim Katen, Oregon

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Believe it or not, a secretary answered the phone and passed me off to the tech department. The guy sounded French.

The one I happened to have as a spare wasn't a sure-test. It was a Sperry. And, come to think of it, the directions are in English and French. Maybe it's made in Canada.

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  • 8 years later...

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