Strange things in the early hours.

[Muhendis]

2 hours ago, bankruatsteve said:

That is why I made the comment - to the thought that switching the wires at the light would somehow fix the problem.

No such luck. Bench testing the light produced a different but related problem. 

I use an antistatic mat which is earthed* and, with the LED pcb assembly siting on the mat half the LEDs glowed dimly. Placed some insulating paper between the two and the LEDs were all off. 

It made not a scrap of difference when the live and neutral were swapped. 

I did notice that the isolated aluminium backplane of the LED pcb was charged. Ouch. 

 

I have since discovered that the Safe-T-Cut in the CU is non functional from the test button. New one should be here in a day or so.

 

* antistatic mat is a slightly conductive rubber mat used to ground a technician so that he/she doesn't zap any delicate electronic components by discharging into them.

[Muhendis]

7 hours ago, Gsxrnz said:

Interesting thread. 

 

I've had similar problems to all those mentioned - and while my brain tells me that science is a universal fact, my heart tells me that electrickery in Thailand somehow manages to conform to non-scientific principles.

It's a combination of the village electrician and the Chinese electrical fittings that confounds scientific principles.

[Muhendis]

3 hours ago, khunPer said:

If you use induction from high power lines - or even some radio waves close to a transmitter - you might have free power for your lighting...

I heard, a long time ago, about someone who did just that near the Eccleshall transmitter near Birmingham (UK). He used a quarter wave aerial a few hundred metres from the transmitter. Cost him a lot in fines. 

[Crossy]

15 minutes ago, Muhendis said:

I heard, a long time ago, about someone who did just that near the Eccleshall transmitter near Birmingham (UK). He used a quarter wave aerial a few hundred metres from the transmitter. Cost him a lot in fines. 

 

Yeah, There was also a chap doing the same with the Crystal Palace TV transmitter. They did him for not having a TV licence.

 

As an apprentice we did a project that was a medium wave radio powered by the long wave 200kHz Droitwich transmitter (check out the ZN414 one chip radio https://www.cool386.com/zn414/zn414.html), it worked but wasn't exactly portable needing a loooong wire for the power reception.

[khunPer]

1 hour ago, Muhendis said:

I heard, a long time ago, about someone who did just that near the Eccleshall transmitter near Birmingham (UK). He used a quarter wave aerial a few hundred metres from the transmitter. Cost him a lot in fines. 

We also had a case in Denmark - it was by the 300kW "Kalundborg Long Wave Transmitter" - he also got fined, the story was that he actually took power from the transmitter by heating his house from it, I don't know if that part is true. it's long time ago...????

[AustinRacing]

Be careful. You may be living in a haunted house. Direct your research into finding out if someone had passed away in the house or nearby. Perhaps round LED lighting had something to do with it and the ghost is not too pleased about it. Perhaps try a different shape lighting. 

[RocketDog]

On 12/2/2021 at 5:25 PM, Crossy said:

Hmmm, the usual reason for this type of thing is a switched neutral, you've not had any work done or a new meter recently have you? Can you verify that the polarity is indeed still correct just in case.

 

It's possible that something has been nibbling on your wiring and cause a High-Z leak, maybe some damp has got in with a similar result.

 

I had a similar problem in a rental house two years ago. It was a circular fluorescent. Not full brightness but the intermittent glow.

I read a post from you advising putting a capacitor, like a few uF/250v such as used for fans, right across the bulb N to Line to act as a lower impedance shunt than the bulb or LED. Theoretically a high value resistor should work as well but harder to find. The capacitors are readily available locally but cheap on Lazada as well.

 

That worked. Should work for the OP. As an EE I knew it had to be a low current leakage issue but didn't flash the obvious solution.

 

Well done Crossy.

[thaibeachlovers]

22 hours ago, millymoopoo said:

Probably just picking up a little EMF (electro magnetic interference), LEDs are very very efficient, requiring very small amounts of electricity to light up.

Take a standard  fluorescent tube (old type, not LED) and stand under one of those high voltage tower lines at night, and the tube lights up, no wires connected. same at radio transmission sites, it's all the 'loose' electrical energy floating around.

Could well be a similar thing to that but obviously on a much smaller scale.!

Reminds me of the time I was driving an AFV on exercise and stopped under high transmission lines. Got a very excited order from commander to move the vehicle, as having some "lightning type electrical activity" down to the aerials.

 

I've had some unintended laffs in LOS when the local "electrician" does something very wrong, like when the local guy melted 10 meters of electric cable and the associated switch by making a direct short to earth.

I've also had some hair raising moments like when I discovered a knife switch with no cover spliced into the wires OUTSIDE the house ie no circuit breaker.

[sometimewoodworker]

5 hours ago, thaibeachlovers said:

I've also had some hair raising moments like when I discovered a knife switch with no cover spliced into the wires OUTSIDE the house ie no circuit breaker.

A knife switch on the incoming feed is not at all uncommon, though they usually do have the normal cover and are usually inside the house.

Edited December 9, 2021 by sometimewoodworker

[thaibeachlovers]

On 12/9/2021 at 7:23 PM, sometimewoodworker said:

A knife switch on the incoming feed is not at all uncommon, though they usually do have the normal cover and are usually inside the house.

This wasn't for the main house feed. It was a solitary wire ending at the uncovered knife switch in the car port ( cunningly covered with stuff so as to kill the unwary that put hands without looking first ), and I think the BIL used it for arc welding as an arc welder tripped the circuit breaker.

[Muhendis]

On 12/8/2021 at 4:41 PM, Muhendis said:

 

I have since discovered that the Safe-T-Cut in the CU is non functional from the test button. New one should be here in a day or so.

A brief word about Safe-T-Cut mentioned above.

Please follow the rule and test regularly. Monthly is recommended.

I just replaced mine because the test didn't work.

Curiosity being what it is, I dismantled the faulty unit which, at ten years old is well out of guarantee.

Cause of failure was the solenoid which was pretty well jammed and could not possibly have saved any poor soul in the event of an electrical fault.

Reason for the jam was the plastic coil former tube had shrunk over time and was firmly gripping the armature preventing it from moving.

 

The phantom event of the flashing light is yet to be fixed however, following a few tests I am now firmly convinced that the leakage causing the problem is due to stray coupling between wires. Inspection revealed no sign of rat damage.

I hope you can follow my reasoning as follows:

Light circuit mcb isolated at the CU and, using a high impedance meter, voltage measured at the mcb output was about 40v. 

Switch off each of the other mcb's and the voltage on the light circuit mcb decreased with each action. 

Each mcb (I have 10 of them) was then switched on and off and the voltage measured at the light circuit mcb.

This voltage was between 2 and 6 volts.

A 1kΩ resistor between live and neutral of the light circuit mcb in the off state reduced this to zero.

There is no useful power leakage but there is enough to charge up the smoothing capacitor in the light fitting driver circuit which would cause the light to flash discharging the capacitor which would then recharge and so on.

Fix could be to fit a two way switch with a 1kΩ resistor between the "off" terminal and neutral. A capacitor across the light fitting would do the trick but that would also increase power consumption of the light which might however be less of a cost than the switch idea.

[Muhendis]

Epilogue

 

Finally the problem seems to be resolved.

After a bit of insulation testing and a whole load of head scratching I removed the CU earth to Neutral link. I then noticed that there was a voltage difference of about 40v between my consumer unit earth and the incoming neutral from PEA. My inverter input to the CU was similar. The inverter floating neutral was easily fixed by linking earth to neutral at the inverter.

The PEA earth/neutral voltage had me suspecting my earth rod because I had no reason to think PEA had not earthed the neutral feed at the transformer and a few posts. I was about to buy a new rod to fix what I thought was my problem when my wife casually mentioned that PEA were working in the village.

What were they doing?

They were replacing the transformer which had been faulty for some time and had finally attempted to achieve terminal velocity. Electrics are now back to normal and faith in PEA sunk a bit lower.

[NanLaew]

I read that some flickering light issues arise when replacing regular incandescent bulbs on a two-way switch system (such as a hallways or stairs) with LED lighting. My mate currently has this issue. It doesn't start as soon as the LED's are installed but apparently 'grows' with time.

[Muhendis]

1 hour ago, NanLaew said:

I read that some flickering light issues arise when replacing regular incandescent bulbs on a two-way switch system (such as a hallways or stairs) with LED lighting. My mate currently has this issue. It doesn't start as soon as the LED's are installed but apparently 'grows' with time.

Yes. This is a case where two wires are in close proximity to each other. One of them is live and the other, connected to the light,  is a very high impedance. (It is high impedance because of the design of the driver circuit of the the LED light.) Electricity "leaks" between the two wires because of this close proximity. There is a fix for it which involves fitting a mains rated capacitor across the light fitting terminals. It's a job for an electrician so Don't try this at home unless your partner knows a bit about resuscitation. 

 

I can only hazard a guess as to why this happens after some time. It's probably due to ageing (something we all have to get used to I guess) of one of the components in the light driver circuit. 

Edited January 22, 2022 by Muhendis
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