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Posted
I bought one of these circuit testers last week and all my sockets bar one are OK, but that one is showing live and neutral reversed.
 
It's the one I have all my computer kit plugged into and it's always worked fine in 13 years. There is, however, a hum from my speakers when everything is switched off. Could this cause the hum or is it more likely an earthing problem?  The plug is  three pin to an extension lead.  I have no idea if the extension lead is earthed yet until I test it at the weekend.  
 
Need I bother reversing the cables at the back of the socket?  I can do it perfectly well, but I tend to believe that if it ain't broke, don't fix it.
 
I haven't taken the socket off and looked at the wiring to check for an earth connection yet, but will check it out at the weekend when I have time.  
 
I did replace a damaged exterior weatherproof socket in our back yard a few years back and that was earthed, so I suspect this one will be.
 
(BTW, the photo has been flipped 90 degrees, the socket isn't installed vertically!) ????

Elec Tester.jpg

Posted
10 minutes ago, Mister Fixit said:

Need I bother reversing the cables at the back of the socket?  I can do it perfectly well, but I tend to believe that if it ain't broke, don't fix it.

There is no absolute need to reverse the line and neutral.
 

However if you bought a line tester you wanted to check so why not?

 

If it creates a problem you can also switch them back 

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Posted

I'm trying hard to understand why a person would buy a tester, test all the circuits and then not act when they found out that one was wired incorrectly. Perhaps it would have been more cost effective to have not bought the tester since the outcome and safety aspects are the same.

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Posted (edited)
1 hour ago, bankruatsteve said:

Is your tester also showing open ground?  

No.  It's showing what's in the photo I took and posted on here.

Edited by Mister Fixit
Posted
10 minutes ago, Brierley said:

You seem confused but hey, as long as you're enjoying yourself that's all that matters.

 

And you seem to enjoy wasting your time making fatuous posts.

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Posted

the hum from the speakers is probably from the unearthed extension.

you might also get low intensity shocks from unearthed equipment.

 

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Posted (edited)

For computer equipment it does not matter. You don't have to change any wire.

 

And about the tester: I actually also just ordered one. I am not really interested to test all my sockets, because for most devices it does not matter at all.

I bought the tester to be able to use something like this.

On those thinks it does matter which wire is what.

sfxuj3.jpg

 

 

Edited by OneMoreFarang
  • Like 1
Posted
1 hour ago, tgw said:

the hum from the speakers is probably from the unearthed extension.

you might also get low intensity shocks from unearthed equipment.

 

 

Yes, that has already been suggested elsewhere.  I'll check the extension when I get time, but no, never any low intensity shocks from anything, ever.

 

The extension has a moulded 3 pin plug, as in the photo, but I can open it up later and put a meter on and check the earth cable continuity - assuming it actually has an earth cable!

Posted (edited)
1 hour ago, Mister Fixit said:

No.  It's showing what's in the photo I took and posted on here.

The photo is why I asked.  The lights shown on "Open Ground" looks like not correct.  (?)

 

Anyway... you should be able to use your tester on the extension strip also.

 

Edited by bankruatsteve
Posted
11 minutes ago, bankruatsteve said:

The lights shown on "Open Ground" looks like not correct.  (?)

 

The photo shows the tester reports there is ground.

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Posted
On 5/19/2021 at 8:37 AM, bankruatsteve said:

Is your tester also showing open ground?  

in a Thai house, you could almost bet on there being no ground. 

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Posted
On 5/19/2021 at 8:37 AM, bankruatsteve said:

Is your tester also showing open ground?  

 

On 5/19/2021 at 12:38 PM, tgw said:

 

The photo shows the tester reports there is ground.

Think it only shows active / neutral reverse - maybe after correction it will report ground condition.

never used one - multimeter does me.

Posted

Try the tester in one of the sockets on the extension lead.

 

Some extension leads, usually the ones that have sockets that can take many different plugs, have the pos/neg reversed. 

 

This would solve your your reversed polarity problem from that plug.

 

I started a thread about this some time ago entitled something like "Thai electricity is different" but search function is useless, so can't find it now.

 

????

 

 

Posted

Most low-end extension cords have a three pin plug on the end of 2-conductor power cord: no ground. I wouldn't buy one on lazada expressly for that reason. Buying retail, you have the opportunity to test it first. If it is in a sealed bubble pack that can't be opened and tested, look for one that is more accessible.

 

I found Belkin were wired correctly (3-pin plug and grounded using 3-conductor wire) as well as accommodating UK style plugs (3 square pins) but they aren't marketed here any more (out of stock for years) and finding any robust outlet strips that work with a UK plug is getting harder. I bought about 8 of these in 3, 4 , 6 and 10 socket configurations years ago and they're all still working.

 

belkin4.jpg.109734ddc59430b93a136cac445d422d.jpg

Posted
On 5/19/2021 at 8:05 AM, sometimewoodworker said:

There is no absolute need to reverse the line and neutral.
 

However if you bought a line tester you wanted to check so why not?

 

If it creates a problem you can also switch them back 

 

If a more modern home build with RCBO or RCD and whatever other current-leakage detecting devices then maybe the reversed line/neutral isn't a major issue?

 

How about older home builds with just a single dual-gang line/neutral breaker that feeds multiple single breakers in the consumer unit feeding all the outlets?

 

Isn't the reversed line/neutral a potential hazard on appliances with external, touchable metal? Especially one that may be correctly wired with a 3-pin, grounded power cord but is plugged into a 2-conductor, non-grounded extension cord?

Posted
40 minutes ago, NanLaew said:

Most low-end extension cords have a three pin plug on the end of 2-conductor power cord: no ground. I wouldn't buy one on lazada expressly for that reason. Buying retail, you have the opportunity to test it first. If it is in a sealed bubble pack that can't be opened and tested, look for one that is more accessible.

 

I found Belkin were wired correctly (3-pin plug and grounded using 3-conductor wire) as well as accommodating UK style plugs (3 square pins) but they aren't marketed here any more (out of stock for years) and finding any robust outlet strips that work with a UK plug is getting harder. I bought about 8 of these in 3, 4 , 6 and 10 socket configurations years ago and they're all still working.

 

belkin4.jpg.109734ddc59430b93a136cac445d422d.jpg

 

I buy only Elektra from HomePro. The Earth pin on the plug goes to the Earth pin on each socket. The Live and Neutral are round the right way and the switch turns off the Live pin in the socket.

1168997211_ElectraPowerStrip500.jpg.9b350b619496d2fefd7ca84f09e53951.jpg

When your Live and Neutral are reversed, the power strip switch will be turning off the Neutral and will leave your plugged in device Live.

 

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Posted
6 hours ago, NanLaew said:

If a more modern home build with RCBO or RCD and whatever other current-leakage detecting devices then maybe the reversed line/neutral isn't a major issue?

There is at least 1 Thai  inexpensive device where it is a problem 

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