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From where is this stray 14VAC coming and what can I do about it?


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I was under the impression with modern earth leakage switches in the control box earth was no longer required, input appreciated

 

Also most water heaters have an elb fitted so there could be two to trip and cut off elect

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4 hours ago, sometimewoodworker said:

Effective earthing may allow them to trip before a human is involved and is an absolutely good thing 

Which is exactly why I didn't bother mentioning imbalance in line voltage, it just confuses the issue.

If people believe an effective earth is required for a ELCB (RCD) to operate efficiently, is that a bad thing.?

Especially considering how lax most Thai electricians are, and how antiquated much of Thai household wiring is.!

BTW, in my days (late 60s through 70s) ELCBs (as they were known then) were commonplace on larger electrical installations, condos, factories etc.
But were less common on domestic household switchboards.!

It was the emerging popularity of swimming pools, their associated electrical equipment and several electrocutions that brought on the requirement for domestic RCDs in the 1980s.!

Many western countries have legislation that will not certify an installation without an operating RCD, as Thailand should do.!

Electricity does deserve respect, it can't be seen, smelt or heard, but by 'F' you can feel it.!

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5 minutes ago, millymoopoo said:

Many western countries have legislation that will not certify an installation without an operating RCD, as Thailand should do.!

 

Actually Thailand does, it's just so often ignored and it's not retrospective. 

 

Once you have permanent meter the supply authorites don't give a fart unless they see the meter going backwards (so make sure they don't).

 

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4 hours ago, Crossy said:

 

That's a good connection, is that shower to CU or CU to rod?

Both. I had placed the screw driver about five meters from the grounding rod so I ran a wire from the rod to the screw driver.  So, probe to existing ground wire still dangling by heater, to Gbar in CU, through heavier ground wire to rod, to screw driver, back through temp ground wire to probe.

 

 

Quote

 

Doesn't it have a 200 ohm range?

 

 

Yes, 0.1

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9 hours ago, millymoopoo said:

Whilst there are many respondents to this subject it is worth while understanding some basics.

1: Electricity and wet areas don't mix well.!

2: Effective earthing in these areas is essential.

3: Multiply earthed neutral system, with or without ELCB (safety switch) is appropriate.

Effective earthing in Thailand is often overlooked.

The length of an earth spike is irrelevant, it's effectiveness is.!

A 60ft earth spike into dry ground is almost as ineffective as a 6ft spike into dry ground.

A spot where the ground is permanently moist is essential for an earth spike to work.

So a spikes into the ground near the septic leach drain long enough to be well into the moist area should work.

Several spikes spaced out within the moist area are more effective than one.

If this is not available then a spike long enough to reach into the ground water table should be used.

Earth spikes that join together (male and female screw ends) can be assembled and driven into the moist ground at what ever depth is required.

Testing (megameter) of the effectiveness of earthing is advised.

Multiple earthed neutral systems are appropriate.

This is the long brass bus bar in the main switchboard, it will have all the neutral wires (black or blue) from the house circuits connected into it as well as the main earth wire (green).

This can be divided into two sections connected together by the earth leakage circuit breaker safety switch (ELCB) as a fail safe.

It should be noted that ELCBs (safety switches) do not work when there is no effective earth.

In pre plastic pipe days, electrical safety in wet areas was taken care of by effective earthing of steel and copper pipes and fittings.

In this plastic pipe era safety is now taken care of with ELCBs.

And thus where there is no effective earth ELCBS are useless.!

In this specific situation it may be worth while opening the hot water heater to see the actual heater (boiler), many are small copper tanks with electric elements within, some are now made of heat proof plastic.

If the boiler is copper, test the tank body with the pen volt meter, it should test at 0v, if a voltage is detected and the tank is not earthed, earth it.

Plastic boiler tanks are more difficult to test, the heater element within the tank will have a copper outer shell, some of this outer may be protruding from the tank, test this, it too should be at 0v.

If a voltage is detected and the tank is earthed, the earth is faulty (ineffective).

Refer to above on how to ensure the earth is effective.

Some water heaters come with built in ELCBs but as previously mentioned become useless when there is no effective earth.

ELCBs trip on less than 1v, if the voltage detected is 12v - 14v this suggests, 1: there is no ELCB on the circuit or 2: the earth is ineffective.

A lot of good information here, it will take awhile to digest it all.  Thank you.

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9 hours ago, Grusa said:

It is entirely possible there is an induced voltage between the supply ground and your grounding rod.

It would appear so. Is this normal and what causes it? In your opinion should I do something about it and if so, what?

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8 hours ago, sometimewoodworker said:

The majority of you post is excellent but in your concentration on an ELCB as the safety switch and the way it works you have made a significant error which is drawing a dangerously wrong conclusion (in that if believed people may decide not to install one) 

The function of the vast majority of RCCBs (a common term for your ELCB) that are required to be installed in Thailand and many other countries, is to measure the current on both the line and neutral and if there is an imbalance to cut the circuit NO PERMANENT EARTH CONNECTION IS REQUIRED FOR THEM TO FUNCTION, they work if enough (a very tiny amount) of difference is detected.
 

Effective earthing may allow them to trip before a human is involved and is an absolutely good thing 

This is slightly off-topic but frankly I do not trust ELCB s in Thailand simply because I have been hit hard by 220VAC twice and I think that proper functioning ELCB s , which were installed, should have prevented them both. Each time I got hit I was grounded to an object other than the N which in theory should have activated the ELCB. I compare these to a time prior when I felt a slight “bump” (still 220) and the ELCB did trip. This distrust includes the ELCB s in the shower heaters and that is why I would like to mitigate their need as much as possible.

 

 

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11 hours ago, ellobo said:

This is slightly off-topic but frankly I do not trust ELCB s in Thailand simply because I have been hit hard by 220VAC twice and I think that proper functioning ELCB s , which were installed, should have prevented them both. Each time I got hit I was grounded to an object other than the N which in theory should have activated the ELCB. I compare these to a time prior when I felt a slight “bump” (still 220) and the ELCB did trip. This distrust includes the ELCB s in the shower heaters and that is why I would like to mitigate their need as much as possible.

 

 

The RCCB will not stop you getting a shock, it will reduce the time of a shock to a usually non lethal one. Some RCCDs allow the length of the cutoff to be extended and even bypassed. Electric shock is a strange thing it has a variable effect depending on the person the path through that person among other factors. Correct Earthing is always good but incorrect earthing can be deadly.

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4 minutes ago, sometimewoodworker said:

The RCCB will not stop you getting a shock, it will reduce the time of a shock to a usually non lethal one. Some RCCDs allow the length of the cutoff to be extended and even bypassed. Electric shock is a strange thing it has a variable effect depending on the person the path through that person among other factors. Correct Earthing is always good but incorrect earthing can be deadly.

But they still should trip, right?  These did not.

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7 minutes ago, ellobo said:

But they still should trip, right?  These did not.

 

Did they trip on the "Test" button?

 

Most will only trip between 15 and 30mA, that hurts, a lot! But you probably won't die. 

 

The requirement for a "30mA" RCD is that is must NOT trip at 15mA and it MUST trip at 30mA. So if you get one that goes at 25mA and you only draw 20mA whilst dying it won't open.

 

Hence the requirement that Class-1 appliances must still be earthed, the RCD is secondary protection.

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1 minute ago, ellobo said:

But they still should trip, right?  These did not.

As I mentioned shock is a funny thing, they can be bypassed and need regular testing to make sure they are working.

Do you know for sure that they 1) weren’t bypassed? 2) had been tested within a month? 3) weren’t set so high that you broke the contact before they did 4) that the current was actually going through them?

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2 minutes ago, sometimewoodworker said:

As I mentioned shock is a funny thing, they can be bypassed and need regular testing to make sure they are working.

Do you know for sure that they 1) weren’t bypassed? 2) had been tested within a month? 3) weren’t set so high that you broke the contact before they did 4) that the current was actually going through them?

#1 and 4.  Installed in CU as right out of the box.  The photo attached to my first post is typical.  #3.  No settings provided in this brand of ELCB s.

 

#2.  Probably not, and I doubt most people test every month although I am sure that you and Crossy do, no disrespect intended, but you are not typical when it comes to electrical matters .  Just another hoop that makes me distrust them.  And yes they still trip on the test button.

 

 

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Look, I am not anti-Thai (married to, visited for …, lived for …, yada, yada) nor am I anti-ELCB, but, we all know that sooomtimes in Thailand we get <deleted>. And, I know just enough electrical to be dangerous, so when I walk into the hardware store I have no idea what is good and what is not.

 

So if you all will tell me in your opinion which brand of ELCB is most trustworthy, and what settings I should use, I will replace my existing ELCB s.      TIA

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On 7/21/2021 at 5:48 PM, Crossy said:

 

Yeah, it should be a proper rod, report to your local PEA office.

 

Long time ago now Crossy, and the house also had some typical Thai wiring, inasmuch as the feed for the aircon in the main bedroom came straight from the cables from the power pole in the road!! They had been "hacked into", insulation stripped back and the aircon feed wrapped around them and covered in tape...........never went anywhere near the Dist board, so the aircon was permanently live!!

 

 

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1 hour ago, ellobo said:

So if you all will tell me in your opinion which brand of ELCB is most trustworthy, and what settings I should use, I will replace my existing ELCB s. 

 

Firstly please stop using the old abbreviation, it means something very different in the modern world and should be reserved for the old voltage operated units (which you probably won't find here), please call it an RCD (or RCBO if it has overload protection).

 

Big names are Schneider (Square-D), Siemens, ABB and the commonly referred to "Safe-T-Cut" which is great if you want to add protection to an existing and already full distribution board.

 

Lower cost brands Haco, BTIcino, Chang are also acceptable.

 

If your existing units test ok why replace them? What brand are they?

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1 hour ago, ellobo said:

Look, I am not anti-Thai (married to, visited for …, lived for …, yada, yada) nor am I anti-ELCB, but, we all know that sooomtimes in Thailand we get <deleted>. And, I know just enough electrical to be dangerous, so when I walk into the hardware store I have no idea what is good and what is not.

 

So if you all will tell me in your opinion which brand of ELCB is most trustworthy, and what settings I should use, I will replace my existing ELCB s.      TIA

I am neither pro nor anti Thai, there are some things that are significantly different, some really good, others strange (to my eyes) others not great, but it’s not my country or society so try to accept mostly.

 

There are things available that are very poor quality and may barely function, generally higher priced items are better. 
 

If your RCCBs apparently aren’t working then it’s possible that they do work but are incorrectly installed or that they are actually faulty so if you can find someone who can check to see if they are correctly installed and working that should be the first step before buying something that may not be needed 

Edited by sometimewoodworker
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15 hours ago, ellobo said:

It would appear so. Is this normal and what causes it? In your opinion should I do something about it and if so, what?

Yes it is normal. DC can be caused by ground chemistry, but that is not the case here, you are getting AC. It can be induction from overhead or buried power line or some other source, even leakage current from a remote source.

 

It's not my field of expertise, so don't take my word for it!  If it bothers you, simply bond your local ground to the incoming ground if there is one, and to the neutral bus. Take expert advice before doing it. (@Crossy ?)

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On 7/22/2021 at 5:37 AM, Grusa said:

It is entirely possible there is an induced voltage between the supply ground and your grounding rod.

why do some countries supply a ground and other don't? ie France doesn't

And if you're supplied with a ground why are folks using a 'grounding rod' instead?

Yours confused lol

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2 minutes ago, driver52 said:

why do some countries supply a ground and other don't? ie France doesn't

And if you're supplied with a ground why are folks using a 'grounding rod' instead?

 

Because of how the local supply system is organised. Here, like Oz is TNC-S with MEN so you get a solidly grounded neutral to which you connect a further rod and that becomes your "ground". In the UK you won't notice what you have 'coz it's all hidden in the service head.

 

Using a rod instead of the provided "ground" could be because you have an EV charge point or farm animals (very sensitive, cows will stop milking from even a miniscule shock).

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6 minutes ago, Crossy said:

TNC-S with MEN

thanks for the post, it's getting above my pay grade to be honest lol

So in Thailand it's like this?

 

300px-TN-C-S-earthing-EN.svg.png

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5 minutes ago, driver52 said:

thanks for the post, it's getting above my pay grade to be honest lol

So in Thailand it's like this?

 

Pretty much, the split PEN to PE and N happens in the distribution board which confuses a lot of people. There's also an extra ground rod there as well as an N-ground rod at every 3rd  pole.

 

The N generally isn't getting much above ground potential unless there's a serious issue.

 

Note that there's still a lot of places that are TT, so don't go linking N-E unless you KNOW your area is MEN.

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