# Three light receptacle tester blindspots



## matt1124

Yes, since the equipment plugged in's case is now connected to neutral, if you happen to touch it and be a more effective return path for current, you become part of the circuit.


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## emtnut

popsickle said:


> One of the wiring conditions that the ordinary three light receptacle tester is unable to distinguish from correctly wired receptacle is the Neutral and Ground being reversed. While this is no doubt wrong, and rather unlikely to occur in home wiring, does it pose a significant safety hazard if left undiscovered and was used regularly in normal service?


Using a 3 light receptacle tester is just ... well, it's just not what an electrician from Indiana should be doing :no:


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## NormousD

damn I still use a 3 light tester with gfci trip.. what should a real electrician be using?

Let me go out my wallet....


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## HackWork

I use one too. I keep it in my service tray right next to my Wiggy and my package of extra large condoms. 

It's easy to use, it helps in troubleshooting a loose connection, and it's good to show the customer that a receptacle I just installed works instead of having to wait for them to go get a lamp.

If there is a better option than the typical model that every brand makes, without having to jump up to that super expensive Ideal thingie, I am all ears.

ETA: I would like to be able to press a button and put a load on the circuit.


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## wildleg

yes it poses a hazard.

only a diy would ever make that ridiculous mistake.


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## Signal1

I use mine too.

It also makes sure the receptacle is nice and solid.


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## emtnut

NormousD said:


> damn I still use a 3 light tester with gfci trip.. what should a real electrician be using?
> 
> Let me go out my wallet....


His fingers


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## matt1124

Are you being so secretive because you are doing this all over a house you're getting ready to sell and don't want the buyer to google if it's dangerous and find you posting this thread?


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## backstay

popsickle said:


> One of the wiring conditions that the ordinary three light receptacle tester is unable to distinguish from correctly wired receptacle is the Neutral and Ground being reversed. While this is no doubt wrong, and rather unlikely to occur in home wiring, does it pose a significant safety hazard if left undiscovered and was used regularly in normal service?


Your tester doesn’t expose this.


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## chicken steve

All testers _lie_.....~CS~


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## trentonmakes

Signal1 said:


> I use mine too.
> 
> It also makes sure the receptacle is nice and solid.


I sometimes use it on a finish to center the receptacles. Tweak it left or right so they sit flush with the cover plate.

Texting and Driving


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## daveEM

I use it on every receptacle so the man of the house will have it a little easier when he plugs in the vac machine.

Ground that has been plowed aplenty... never mind.


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## telsa

HackWork said:


> I use one too. I keep it in my service tray right next to my Wiggy and my package of extra large condoms.
> 
> It's easy to use, it helps in troubleshooting a loose connection, and it's good to show the customer that a receptacle I just installed works instead of having to wait for them to go get a lamp.
> 
> If there is a better option than the typical model that every brand makes, without having to jump up to that super expensive Ideal thingie, I am all ears.
> 
> ETA:* I would like to be able to press a button and put a load on the circuit*.


TASCO out of Colorado has just such a device.


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## RePhase277

It would be impossible for such a tester to distinguish between a neutral and ground in a properly wired system.


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## HackWork

To answer the OP's question in my own opinion, it's not a big problem or safety hazard. It doesn't happen that often and when it does happen, there usually isn't another issue also happening which is what generally exacerbates it. 

The truth is that there are tens of millions of instances of neutral and ground being bonded more than once in typical dwellings. Whether it be intentionally done like they did in apartments in which they bonded neutral to ground in every sub panel, or accidentally done such as in the case of a neutral touching a metal part.

We try to avoid it when possible because it may cause an issue, but usually doesn't.


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## cabletie

It's just so easy how the red and yellow jewels pry out, that every time I see a coworkers cube tester sitting out, I just have to swap them around. 

Only kidding. That would waste to much of the contractors time. I did have it happen to me once. What a hoot.


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## MechanicalDVR

I like the little 3-light testers for a quick check out of a place and as Trenton says, using them to tweak a receptacle they make a decent handle.


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## macmikeman

trentonmakes said:


> I sometimes use it on a finish to center the receptacles. Tweak it left or right so they sit flush with the cover plate.
> 
> Texting and Driving



Me too. Is that a leftist thing to say nowadays?


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## sbrn33

I have this but I never use it. 
https://www.tequipment.net/ExtechCT...x5n7ZIejDRsWt5sMaeKccwZ1GsZn0viBoCJ_oQAvD_BwE


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## cabletie

sbrn33 said:


> I have this but I never use it.
> https://www.tequipment.net/ExtechCT...x5n7ZIejDRsWt5sMaeKccwZ1GsZn0viBoCJ_oQAvD_BwE


Looks like a nice tester. 

I really like the items frequently bought together, a formaldehyde tester?
I am always curious how much formaldehyde I'm breathing in when I'm switching and plugging.


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## RePhase277

cabletie said:


> Looks like a nice tester.
> 
> I really like the items frequently bought together, a formaldehyde tester?
> I am always curious how much formaldehyde I'm breathing in when I'm switching and plugging.


That's that "new house" smell. A house with brand new carpet, paint, appliances, countertops, etc. is just running over with formaldehyde and other chemicals that probably shouldn't be lived around.


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## brian john

I own a boat load of test equipment and still find a 3-light "bug-eye" tester practical, used it this weekend at a house I am trying to sell.


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## active1

It's required for convention work. Many put it on a key chain retractor.

I never got one, but a many also carry a 5 wire TL tester.
They are full timers. Depending on what company and amperage they use different configurations. 

For most of the typical booth show stuff that's all you need. Does it light up and monitors turn on. Lot's of retail electronics have a wide range.

The power crews uses meters to check. For special voltages, prototypes, machines, or other super expensive items voltage would tested and many times shown to the customers rep.


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## popsickle

Thanks for all the responses. Yes, I am from Indiana, I saw that in my profile when I checked it. So much for cloak and dagger, huh emtnut  

A prediction of mine is if this specific wiring mistake happened on a GFCI protected branch circuit, the GFCI would trip immediately upon any device plugged into it pulling any load (or at min., above the threshold trip current of the GFCI). I would think this annoyance would lead to it's discovery if occurring on a GFCI protected circuit. But on a regular circuit, I could see it going undetected. 

While I used the example of an incorrectly wired wall outlet, the real basis for the question is something else, so anyone looking to buy a house in Indiana, breathe easy.
What that something else is, well, I'll just say in my case happens downstream of building wiring.

Someone at my company forwarded me an article on the web on the subject of the cube tester and specific outlet wiring variations for which it will test good. One of these is particularly dangerous, especially for musicians using lots of interconnected electrical gear, the notorious reverse polarity bootleg ground, found in older wired buildings that had their two wire outlets upgraded to 3 wire without running new wire back to the panel. When this type of shortcut upgrade was done, the intent was to connect the bootleg ground on the neutral of the circuit, which it is on the neutral of the receptacle. But, the issue is the receptacle's neutral is Line Potential in a reverse polarity situation making the bootleg ground Line Potential also.


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## HackWork

A GFCI receptacle will function normally with the line side neutral and ground reversed.


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## popsickle

HackWork said:


> A GFCI receptacle will function normally with the line side neutral and ground reversed.


Yes, but this is different from a receptacle on a GFCI protected circuit
with its ground and neutral reversed.


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## HackWork

popsickle said:


> Yes, but this is different from a receptacle on a GFCI protected circuit
> with its ground and neutral reversed.


It depends where the neutral and ground are reversed.


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## RePhase277

I haven't been in this trade for 50 years like some guys, but I bet I've been inside enough receptacle boxes to rival some of those guys. I've seen plenty of hot-neutral reversed, open ground, open neutral, and bootleg ground and bootleg neutrals.

But I have never, ever seen a hot-ground or neutral-ground reversed. I think such a situation must be exceedingly rare.


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## MTW

RePhase277 said:


> I haven't been in this trade for 50 years like some guys, but I bet I've been inside enough receptacle boxes to rival some of those guys. I've seen plenty of hot-neutral reversed, open ground, open neutral, and bootleg ground and bootleg neutrals.
> 
> But I have never, ever seen a hot-ground or neutral-ground reversed. I think such a situation must be exceedingly rare.


I see.


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## RePhase277

MTW said:


> I see.


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## active1

Had 2 JWs connect a few XFMR just this year.
They called me because the volt readings were way off and they didn't know why.
Got there and the one with it on put his ear up against the side of the XFMR and said it was making a funny noise.
Starting checking and turned out the crew pulling the primary got the phase colors swapped between the full size EG and a leg.

Don't know who was the bigger screw up. The crew that got the phasing labeled backwards. The 2 that couldn't figure it out. Or the guy luckily was on a wood deck when he put his ear on a cabinet connected to 277v. 

Had another job where an inspector plugged in and all 3 lights lit up. That's not one of the choices on the chart. Turned out to be miscommunication on bonding the neutral. Panel installer thought the XFMR installer was doing it, vise versa. Or they both and the foreman forgot to address it.

Even those ideal sure tester have an issue with false boot leg ground reporting. Every testers got it's weakness or way it could be misunderstood. That's where the skill comes in of what to use where.

The plug testers are lower cost, which is good when your working in busy areas where things can walk fast.


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## shocksystems

HackWork said:


> I use one too. I keep it in my service tray right next to my Wiggy and my package of extra large condoms.
> 
> It's easy to use, it helps in troubleshooting a loose connection, and it's good to show the customer that a receptacle I just installed works instead of having to wait for them to go get a lamp.
> 
> If there is a better option than the typical model that every brand makes, without having to jump up to that super expensive Ideal thingie, I am all ears.
> 
> ETA: I would like to be able to press a button and put a load on the circuit.


I love these testers and use one almost daily. I but the cheap ones at harbor freight and carry it in my pocket. I wish I could find one that displayed the voltage on it as well. That is the biggest reason I pull out my meter. This would avoid that.

Sent from my A1P using Tapatalk


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## WrongWire

shocksystems said:


> I love these testers and use one almost daily. I but the cheap ones at harbor freight and carry it in my pocket. I wish I could find one that displayed the voltage on it as well. That is the biggest reason I pull out my meter. This would avoid that.
> 
> Sent from my A1P using Tapatalk


Kind of surprised they don't have that built in yet. Would sell like hotcakes.


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