How do socket testers detect live/neutral switched? - Page 1
Forum section: electronics / general

author: XOIIO
author_rank: Super Contributor
timestamp: July 19, 2014, 01:13:35 am
content: 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

author: xygor
author_rank: Regular Contributor
timestamp: July 19, 2014, 01:24:39 am
content: 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.

author: XOIIO
author_rank: Super Contributor
timestamp: July 19, 2014, 01:33:16 am
content: Quote from: xygor on July 19, 2014, 01:24:39 amLol yeah just saw thatWhoops.

author: xygor
author_rank: Regular Contributor
timestamp: July 19, 2014, 01:38:26 am
content: 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.

author: XOIIO
author_rank: Super Contributor
timestamp: July 19, 2014, 02:01:36 am
content: Quote from: xygor on July 19, 2014, 01:38:26 amYeah, 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.

author: XOIIO
author_rank: Super Contributor
timestamp: July 19, 2014, 02:09:41 am
content: 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.

author: ajb
author_rank: Super Contributor
timestamp: July 19, 2014, 02:21:43 am
content: 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=1And yes, circuit breakers are supposed to interrupt the line, not the neutral.

author: G7PSK
author_rank: Super Contributor
timestamp: July 19, 2014, 08:11:14 am
content: 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.

author: GeoffS
author_rank: Unknown
timestamp: July 19, 2014, 08:15:50 am
content: Something like this?

author: SeanB
author_rank: Super Contributor
timestamp: July 19, 2014, 11:05:58 am
content: 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.

author: GreyWoolfe
author_rank: Unknown
timestamp: July 19, 2014, 12:14:02 pm
content: Quote from: XOIIO on July 19, 2014, 01:33:16 amC'mon, it's much more fun this way. Besides I always have my testes with me, I may not have an indicator lamp

author: t2000kw
author_rank: Newbie
timestamp: July 20, 2014, 01:59:21 am
content: Quote from: GreyWoolfe on July 19, 2014, 12:14:02 pmJust 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.

author: Monkeh
author_rank: Super Contributor
timestamp: July 20, 2014, 02:51:45 am
content: Quote from: XOIIO on July 19, 2014, 02:09:41 am...Line, but if you can't recall I suggest you don't go poking..

author: XOIIO
author_rank: Super Contributor
timestamp: July 20, 2014, 02:58:34 am
content: Quote from: Monkeh on July 20, 2014, 02:51:45 amNot going to rewire the house lol, just wanted to know the correct one.