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FarangRimPing

How can this be - Leakage?

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Our electricity from the PEA has been very unstable until recently. Voltage drops to 170 or less were not uncommon, and frequent blackouts.

 

PEA installed a new transformer a few hundred meters up the road about a month ago and this has vastly improved the stability. However, because of our poor experience, I leave a "HABOTEST Advanced GFCI Electric Socket Tester Automatic Neutral Live Earth Wire Testing Circuit Polarity Detector Wall Plug Breaker Finder Electric Leakage Test with Voltage Backlight LCD Display" plugged into an outlet.

 

https://www.lazada.co.th/products/habotest-advanced-gfci-electric-socket-tester-automatic-neutral-live-earth-wire-testing-circuit-polarity-detector-wall-plug-breaker-finder-electric-leakage-test-with-voltage-backlight-lcd-display-i403306554-s782958616.html?

 

It was indicating that every thing was perfect until this morning, when it started showing 3 red dots, which means: "Live/GRD reverse, missing GRD", and it shows this in every outlet of the house.

 

So I put a voltmeter in an outlet, and these are the approximate readings:

Live-Neutral = 230 volts

Live-Ground = 195 volts

Neutral-Ground = 35 volts

 

Any idea what is going on? Is this a PEA problem or specific to my house?

 

Thank you.

 

 

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Make measurements from L, N & E to a "real" earth (screwdriver in the lawn).

 

It looks like you've lost the earth rod.

 

Can you post a photo of your distribution board with the lid off, we need to see if you have MEN.

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Not sure that this helps, it's the panel which I have easy access to and all indoor outlets connect to this. The house ground also connects to it. House ground is about a meter away, driven down below the floor.

 

ElectricalMainPanel.thumb.jpg.13a5881c0ebca9ada86bb2dea6712cf1.jpg

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25 minutes ago, Crossy said:

Make measurements from L, N & E to a "real" earth (screwdriver in the lawn).

 

It looks like you've lost the earth rod.

 

Can you post a photo of your distribution board with the lid off, we need to see if you have MEN.

Or  is it possible it  is associated problem caused  by a  neighbour due to the  combined neutral/ground. Backfeed .

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24 minutes ago, FarangRimPing said:

Not sure that this helps, it's the panel which I have easy access to and all indoor outlets connect to this. The house ground also connects to it. House ground is about a meter away, driven down below the floor.

 

The fat black wire on the ground bar, does it just go to the rod?

 

If you can't get to the actual rod, try adding a temporary rod (that screwdriver again) connected to the ground bar and re-try the outlet tester.

 

We really need to see those voltage measurements to the screwdriver ground.

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Deleted by poster. Re-read the OP and my question had already been answered.

Edited by MartinL

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1 hour ago, Crossy said:

 

The fat black wire on the ground bar, does it just go to the rod?

 

If you can't get to the actual rod, try adding a temporary rod (that screwdriver again) connected to the ground bar and re-try the outlet tester.

 

We really need to see those voltage measurements to the screwdriver ground.

Yes, goes directly to the rod. (wire in wall, so unlikely that it breaks during the night.)

 

If it were simple a broken ground, wouldn't there be zero (or close to) reading for the Live-Ground?

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11 hours ago, FarangRimPing said:

If it were simple a broken ground, wouldn't there be zero (or close to) reading for the Live-Ground?

 

Floating wires can read all sorts of interesting voltages with a high impedance meter and those little plug-in testers can get confused (capacitive coupling).

 

Do try making those measurements to a screwdriver in the lawn.

 

A high resistance neutral between the meter and the house may be on the cards, so you should check the voltages to real earth at the meter too.

 

A poor star point ground or heavy load imbalance on the transformer could also cause the neutral to pull significantly above zero. If the neutral is well above ground at the meter, time to call the supply authority.

 

Whilst you're at the meter have a look at a few poles, do you see an earth strap from the neutral (the top wire on the small insulators) down the pole to a ground rod?

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Late yesterday, an electrician friend came and checked out the electrics. (He only does commercial work, such as malls, department stores, and the like.) He concluded that the problem was coming in at the meter. We didn't have time to call PEA yesterday.

 

Interestingly, everything works fine this morning. No voltage coming through the Neutral any longer.

 

I will monitor closely (tester plugged in all of the time) and will call PEA if the problems recurs.

 

Sincere thanks for the advice given.

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Do keep a weather-eye on it.

 

It's possible that PEA did have an issue that they've fixed, it's also possible you have a fizzy joint somewhere on your neutral.

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On 11/29/2019 at 4:51 PM, Dumbastheycome said:

Or  is it possible it  is associated problem caused  by a  neighbour due to the  combined neutral/ground. Backfeed .

No.

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10 hours ago, Crossy said:

Do keep a weather-eye on it.

 

It's possible that PEA did have an issue that they've fixed, it's also possible you have a fizzy joint somewhere on your neutral.

Also possible the OP crossed terminals at the initial monitor. 35V neutral to ground isn't an abnormal reading either. 

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On 11/29/2019 at 4:23 PM, BritManToo said:

I'd disconnect the live feed into the house and run everything off the neutral/ground ........ free electricity.

Best post of the week! 

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I've posted this previously.!

So with such low Thai electrical standards/workmanship it is essential you have:
1 a functioning earth leakage circuit breaker (earth safety switch) wired correctly.

2 all power circuits (especially Bathroom Laundry and Kitchen) are earthed.

3 a multiply earthed neutral system.

4 and finally, the most important an effect earth copper spike/rod (or 3) placed in a permanently wet area like a well or septic system.
'4' is vitally important as too often earth spikes/rods are placed in dry earth where they are ineffective.
An fully functioning 100% effective earth system will always have 0 volts irrespective of how many volts are applied to it.
The earth leakage circuit breaker merely measures the transient current/voltage between the earth system of the house and the earth spike/rod, when any difference is detected it trips the breaker.

Had your earth system been effective as described above there would be 0 volts reading and the circuit breakers would have blown.!

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