How do socket testers detect live/neutral switched?

[XOIIO]

Just curious, the amprobe socket tester (model ST102A) that I got to see why the site wiring fault is on, on my UPS and power bar, can detect if hot and neutral are switched, just curious how they do it.

Also, yay, this house sure has safe wiring, open ground and hot/neutral switched 

[xygor]

If you connect your testes between ground and neutral, and neutral is really hot because it is swapped, you will have a memorable experience.

Edit: Replace your testes with an indicator lamp, and you have the part of the fault detector the detects the swap.

[XOIIO]

If you connect your testes between ground and neutral, and neutral is really hot because it is swapped, you will have a memorable experience.

Edit: Replace your testes with an indicator lamp, and you have the part of the fault detector the detects the swap.

Lol yeah just saw that  Whoops.

[xygor]

Just a capacitor or resistor in series with the LED to limit the current.  Probably a diode to protect the LED against reverse voltage in series with or in parallel with it as well.

[XOIIO]

Just a capacitor or resistor in series with the LED to limit the current.  Probably a diode to protect the LED against reverse voltage in series with or in parallel with it as well.

Yeah, edited that out since I looked closer and it is neons, just not as much exposed, that's why I was curious about it, probably similar, wish this wasn't sealed so I could open it and see what's inside.

Pretty good one though, it detects open ground, open neutral, open hot, hot/gnd reverse, and hot/neutral reverse.

[XOIIO]

Oh yes, can't recall, are circuit breakers supposed to be on live or neutral? I'm sure it's live but I can't recall.

[ajb]

I think this link actually came from this forum, but even so I think it's worth reposting.  Of course if your UPS is complaining about the site wiring, you probably don't have one of the hidden problems described here, but worth noting for future reference.

http://ecmweb.com/contractor/failures-outlet-testing-exposed?page=1

And yes, circuit breakers are supposed to interrupt the line, not the neutral.

[G7PSK]

I have a socket tester that is just 3 neons and a whole lot of resistors in a network, not traced it through but as there is more than 3 of them it must be something more than just placing a neon on each pin. 

[GeoffS]

Something like this?

[SeanB]

The one I use that does both polarity checking, earth leakage trip current test and detection of an open earth. The detection of a reversed live is by having a small LCD display that is connected via a capacitor and resistor to the metal adjustment knob, so that if the earth floats high you will have it light up to display a danger symbol when you touch the knob. Tested and it works.

[GreyWoolfe]

If you connect your testes between ground and neutral, and neutral is really hot because it is swapped, you will have a memorable experience.

Edit: Replace your testes with an indicator lamp, and you have the part of the fault detector the detects the swap.

Lol yeah just saw that  Whoops.

C'mon, it's much more fun this way.  Besides I always have my testes with me, I may not have an indicator lamp 

[t2000kw]

C'mon, it's much more fun this way.  Besides I always have my testes with me, I may not have an indicator lamp 

Just make sure that the alligator test leads are firmly grabbing the testicles or you might not have enough electrical contact to really know if there's continuity or not where it shouldn't be. The bigger alligator clips work the best. For big ones, you can use battery cable clamps.

[Monkeh]

Oh yes, can't recall, are circuit breakers supposed to be on live or neutral? I'm sure it's live but I can't recall.

...

Line, but if you can't recall I suggest you don't go poking..

[XOIIO]

Oh yes, can't recall, are circuit breakers supposed to be on live or neutral? I'm sure it's live but I can't recall.

...

Line, but if you can't recall I suggest you don't go poking..

Not going to rewire the house lol, just wanted to know the correct one.