[SOLVED] Mains leaking currents causing problems in my house

[betwixt]

Neutral and Earth are usually bonded together but not at the socket, it is done back at the distribution transformer where both have a real 'planet Earth' ground. If you bond them at the socket and a fault occurs, the earth pin could become live and hence extremely dangerous. Consider what would happen if the neutral connection back to the box went open circuit, your PC would stop working but the case would be at 230V AC!

Q: Do you have a ring feed in your home/apartment? What is the purpose of middle contact (longer one) on UK type mains plug?

Each room here is wired in a ring, Earth, live and Neutral arrive at the first socket, are wired to the next socket and at the end of the ring all three return to the fuse box where they are wired in parallel with the first wires. It means there are two paths for current to flow (two directions around the loop) which gives half the resistance and better protection if a break occurs. Part of the statutory electrical inspection is to break the loop and measure the resistance around it to confirm connectivity. For a single room with (in my case) 8 outlets, the live and neutral are 2.5mm² solid copper. the Earth wire is slightly thinner, I would guess 1.5mm and the trip rating is 32A. I have 'real' Earth points to 1m long copper rods at each side of the house as well as the connection back to the transformer. The long pin on the 13A rated UK sockets is the Earth pin, the extra length ensures it connects before live and neutral and it also opens a shutter mechanism in the sockets that otherwise closes off the holes for live and neutral.

I do actually have a 125A 3-phase mains supply here but it is unusual in the UK and I only use one phase and neutral within the house. In most places the neutral and rotating phase connections are outside the property at the buried distribution cable.

Brian.

 

[eagle1109]

Neutral and Earth are usually bonded together but not at the socket, it is done back at the distribution transformer where both have a real 'planet Earth' ground.

Yep that's a big possibility in our district power distribution, I took these photos just now.

If you bond them at the socket and a fault occurs, the earth pin could become live and hence extremely dangerous. Consider what would happen if the neutral connection back to the box went open circuit, your PC would stop working but the case would be at 230V AC!

Oh yeah because ground is still connected and completing the circuit! like if I switched the power from the PC off, it's still connected with the ground path !! I guess.

Each room here is wired in a ring, Earth, live and Neutral arrive at the first socket, are wired to the next socket and at the end of the ring all three return to the fuse box where they are wired in parallel with the first wires. It means there are two paths for current to flow (two directions around the loop) which gives half the resistance and better protection if a break occurs.

Part of the statutory electrical inspection is to break the loop and measure the resistance around it to confirm connectivity. For a single room with (in my case) 8 outlets, the live and neutral are 2.5mm² solid copper. the Earth wire is slightly thinner, I would guess 1.5mm and the trip rating is 32A. I have 'real' Earth points to 1m long copper rods at each side of the house as well as the connection back to the transformer. The long pin on the 13A rated UK sockets is the Earth pin, the extra length ensures it connects before live and neutral and it also opens a shutter mechanism in the sockets that otherwise closes off the holes for live and neutral.

That's interesting ! I understand the electrical wiring standards in UK, it's sophisticated of course and ensures higher level of electrical protection.

I don't know why it's different in Saudi Arabia. Does that mean according to my pictures that we have lower protection system ?

I do actually have a 125A 3-phase mains supply here but it is unusual in the UK and I only use one phase and neutral within the house. In most places the neutral and rotating phase connections are outside the property at the buried distribution cable.

Did you have this 125A 3-phase mains supply for extra money from electricity company ? Is it the main electricity source for your house ?

 

[FvM]

Electrical safety standards are basically international. Only some implementation details are specific in particular countries, e.g. current rating of sockets, switches or fuses required for sockets. But the points discussed here are universal. I reviewed some publications form Saudia Arabia and they all seem to refer to recent international safety standards.

Earthing systems accepted for domestic power distribution are TN-S or TN-C-S (mostly used), also TT in combination with RCD (residual current device) if local earth has too high impedance.

TN-C (common wire for earth and neutral is only accepted for industrial installations with PEN wire cross section >= 10 mm².

https://en.wikipedia.org/wiki/Earthing_system

 

[betwixt]

Did you have this 125A 3-phase mains supply for extra money from electricity company ? Is it the main electricity source for your house ?

It's a long story but basically, the cable carries on beyond my house to a three-phase motor on a waste treatment plant nearby. The cables used to be overhead but trees fell across the wires and shorted them together - you can imagine what happens when the output of a transformer similar to the one you showed gets shorted out! I had to install my own underground cable about 150m to the transformer and it still had to be 3-phase so the motor would remain in operation. So I installed a fat 4-core, each 25mm² armored cable (3 phases, neutral and an earth shield) to my house where I only connect to one phase and neutral but a smaller cable continues on to the waste plant motor.

It was expensive and a lot of work but it keeps the lights on!

Brian.

 

[eagle1109]

Electrical safety standards are basically international. Only some implementation details are specific in particular countries, e.g. current rating of sockets, switches or fuses required for sockets. But the points discussed here are universal. I reviewed some publications form Saudia Arabia and they all seem to refer to recent international safety standards.

Yep we have quite good electricity work, the company is actually one company but a huge one running all electricity in Saudi Arabia.

I ran by a project on the red sea which is Jeddah South Thermal Power Plant, you can check it on google maps, there are nice photos about it

Earthing systems accepted for domestic power distribution are TN-S or TN-C-S (mostly used), also TT in combination with RCD (residual current device) if local earth has too high impedance.

wow thanks for mentioning the names of connection standards, "TN-S or TN-C-S" that's what I was searching for. It listed good results on google images Really thanks dude ..

So I hope this is the connection in my apartment for TN-S:

and this for TN-C-S:

But I'm not sure if it's what we have ?!


But aren't TN-S and TN-C-S very similar?

TN-C (common wire for earth and neutral is only accepted for industrial installations with PEN wire cross section >= 10 mm².

https://en.wikipedia.org/wiki/Earthing_system

This one also listed the same results as TN-C-S and TN-S ! So what's the difference ?

It's a long story but basically, the cable carries on beyond my house to a three-phase motor on a waste treatment plant nearby. The cables used to be overhead but trees fell across the wires and shorted them together - you can imagine what happens when the output of a transformer similar to the one you showed gets shorted out!

wow that's really scary ! you're lucky it didn't burn your garden or the green around you, as you are in UK so there are a lot of trees

I had to install my own underground cable about 150m to the transformer and it still had to be 3-phase so the motor would remain in operation.

So the power is basically for this company of waste plant ! and you're sharing the power with them as the power already installed for this company. This is my guess, if it's true then as you're sharing power lines with a company, you also have to pay for power. By installing power meters for each end consumer, right ? Same as everywhere, where power company put like that big distribution room, and each building take big power parallel lines for each building and then, each apartment. And each apartment has a power meter. That's our system.

So I installed a fat 4-core, each 25mm² armored cable (3 phases, neutral and an earth shield) to my house where I only connect to one phase and neutral but a smaller cable continues on to the waste plant motor.

It was expensive and a lot of work but it keeps the lights on!

Brian.

Is it the 125A cable you mentioned earlier ?

So you had to buy the cable and do the installation ? wow that's a lot, the electricity company should've done that for you.

 

[eagle1109]

I called the electricity company booked a ticket, they called me back. And I asked them if the mains is grounded and he told me that the outer lines ground is different then what I have inside the apartment !!! How come ? If the outer is grounded then what I have is grounded !!

I asked him again and he repeated the same information !! There's no another transformer between the distribution room and the building !!

 

[FvM]

What does this mean? As far as we have seen, there's no grounding in your apartment panel. No ground wire available, no grounding of sockets.

We can expect the neutral is grounded at the distribution transformer, and it's most likely also grounded at the house distribution panel.

The utility company isn't responsible for safe installation inside your house, it's the house owner.

 

[Kajunbee]

I called the electricity company booked a ticket, they called me back. And I asked them if the mains is grounded and he told me that the outer lines ground is different then what I have inside the apartment !!! How come ? If the outer is grounded then what I have is grounded !!

I asked him again and he repeated the same information !! There's no another transformer between the distribution room and the building !!

Eagle1109, do you have any idea what or where the gray wires go to. They look like they pass through the box without connecting to anything.

 

[FvM]

I guess it's CATV or telephone.

 

[lggrover]

The leakage current in equipment flows when an unintentional electrical connection occurs between the ground and an energized part or conductor. The leakage in devices is largely due to the imperfections in the insulators or materials that make the component such as the semiconductors and capacitors.
Your home also may have numerous phantom loads, power usage from breaker at your home's service panel (breaker box) and look at the electric meter is an open connection in the circuit, possibly caused by degraded wire insulation.

 

[eagle1109]

What does this mean? As far as we have seen, there's no grounding in your apartment panel. No ground wire available, no grounding of sockets.

The utility company isn't responsible for safe installation inside your house, it's the house owner.

Yep, that's right. I called the owner and he told me that he didn't install a ground to the building.

We can expect the neutral is grounded at the distribution transformer, and it's most likely also grounded at the house distribution panel.

That's possible. My colleagues told me to do a trick to know if there's a leak when I would short the ground to neutral.

>> Connect the PC power cable to an Outlet Power Strip that has more than one outlet; like this one,

Then I must first identify the L and N, then I measure the voltage between the loosed ground and neutral, and check if there are voltages.


Like this diagram:

Eagle1109, do you have any idea what or where the gray wires go to. They look like they pass through the box without connecting to anything.

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I guess it's CATV or telephone.

- - - Updated - - -

OK guys I have some interesting stuff !!

When I applied that trick I posted earlier and tested the power strip, there's an actual voltage between the neutral to ground && from live to ground !!! where did that come from ??!!


The wall outlet isn't grounded !! So when I do this test on the wall, there is no voltage from L-GND or N-GND. But with power strip L-GND is like 110V and N-GND is 90V !! Why ??


Also I did another test which is to connect one probe of the DMM and leave the other floating, that's how I identify the L from N. L would give voltage and N would give something below 1V maybe 500mV.

There are my pictures:

1. First floating test:

This is live because it gives 23V




This is of course is neutral




2. Voltage from L-GND and N-GND on the power strip:

This should be L-GND because it's higher voltage of 103V



This is N-GND





Of course these voltages are the reason for 110V voltage on the chassis.

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Extra photos

This is the power strip from inside



Fuse stuff




Another power strip with same issue



- - - Updated - - -

Of course these voltages are the reason for 110V voltage on the chassis.

I disconnected the power strip and connected the PC power supply to the wall outlet directly .. the voltage on the chassis is like 6V but there is still a shock when I touch the PSU screws on the chassis.

 

[ZASto]

Until you install proper grounding you will feel electric shocks.

Wet your bathroom floor, stand on it barefoot and touch your PC when switched on.
If you survive, please describe the feel (DO NOT DO THIS!!!)

Even if you connect earthing pin to neutral, neutral could be on higher potential than ground. Even that transformers star point is grounded, at your side the neutral could be on higher potential due the bad connections, ....

Another thing, do not use DVM for measuring these kind of "faults", use ordinary meter with needle. DVMs have way to high input resistance and the measurements are on the unreal side.

 

[FvM]

The various measurements are showing what you can expect with an unconnected ground and filter capacitors in the PC PSU, that are pulling the ground to the center betwen L and N.

To identify L and N, you measure the voltage to a true ground, e.g. a water pipe.

Connecting the wall outlet ground terminal to neutral will work at first sight but is not safe. If the neutral wire is interrupted somewhere between the central grounding point and the outlet, the ground terminal will be pulled to 230 V by the load, feeding a hazardous contact voltage to all connected device chassis.

That's why safety standards require separate ground wires starting from the house distribution panel.

What can you do if the house installation lacks separate ground wires?
1. Only use electrical equipment with double/reinforced insulation. It's equipped with two pin connector and doesn't require a ground terminal. Unfortunately not applicable for e.g. dish washers, and unusual even for low power devices like standard desktop PC.

2. You can apply TT grounding scheme, connecting the device chassis to reliable local ground. There's however a risk that a short between chassis and L can't be handled by the local ground because it's impedance isn't low enough.

3. TT grounding scheme is usually combined with residual current breaker (or residual current device - RCD). It disconnects L and N if the leakage current exceeds a dangerous level.

 

[ads-ee]

Yep, that's right. I called the owner and he told me that he didn't install a ground to the building.

This alone would make me move out of that apartment and find another where the owner doesn't want their tenants to get electrocuted by 230V.

Until you install proper grounding you will feel electric shocks.
Wet your bathroom floor, stand on it barefoot and touch your PC when switched on.
If you survive, please describe the feel (DO NOT DO THIS!!!)

You are suggesting the wrong person should do this. The OP should ask the owner to do this. If the owner survives then they can ask for reduced rent due to a hazardous living conditions. If the owner doesn't survive well it serves them right for leaving off the ground connection. ;-)

 

[ZASto]

This alone would make me move out of that apartment and find another where the owner doesn't want their tenants to get electrocuted by 230V.


You are suggesting the wrong person should do this. The OP should ask the owner to do this. If the owner survives then they can ask for reduced rent due to a hazardous living conditions. If the owner doesn't survive well it serves them right for leaving off the ground connection. ;-)

You are absolutely right about "tester"
If he does not survive, anyway will be "grounded"

 

[eagle1109]

You are absolutely right about "tester"
If he does not survive, anyway will be "grounded"

I just bought a plug tester from Aliexpress, it should arrive in a month or so.

 

[betwixt]

Beware, most 'plug testers' work by looking at the difference between the three pins, live, neutral and earth. As you only have two pins it may not work.

There is an alternative that would make you safe but you would have to be careful if other powered devices were connected to the PC, that is to use an isolating transformer. They are basically a 230V in and 230V out transformer but because they use magnetic coupling, no direct connection to the wall socket is made. You would have to power all mains devices attached to the PC from the transformer, if any have a direct connection back to a wall socket they bypass the isolation completely. The only exception is a network connection using CAT-5 or CAT-6 cable and RJ45 plug (the standard for networking) because network ports already have isolation built into them. There is still a small risk of a slight electric shock even when using an isolating transformer but it would be insignificant compared to what you have now.

Brian.

 

[eagle1109]

You are right ! I cancelled the order, because I went through videos on YouTube and they demonstrated that these devices really don't give the required results !

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I have checked some stuff on the web, how about this power strip ? I would be a little bit expensive but not much.


Belkin 12-Outlet Power Strip Surge Protector w/ 8ft Cord – Ideal for Computers, Home Theatre, Appliances, Office Equipment and more (3,940 Joules)

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Or how about installing an RCD between the shorted (bootlegged) neutral and ground ?

First of all this is my thoughts about what's going on between the PSU and the power from the socket.



Is my guessing alright or near the actual problem ?

 

[eagle1109]

How about this protection when doing a bootleg ?

 

[betwixt]

I think the "not grounded" indicator is to warn you the protection isn't going to work. All 'surge protectors" and similar protection devices are filters and over-voltage traps that rely on a good earth being available. Without a 'ground zero' to send unwanted current to, they cannot possibly work and may make your situation considerably worse. Similarly, an RCD is unlikely to have much effect, they look for differences in the live current and neutral current. They should be the same because the current flows in a loop through the appliance (your PC) up one wire and down the other. They 'trip' if current leaks out somewhere and causes an imbalance but without an earth there is nowhere for the leaking current to flow to. The tiny current that gives the electric shocks is far less than 30mA!

Question, is your room at or near ground level? I'm wondering if it is possible to add your own ground through an earthing rod in the ground.

Brian.