Trying to understand household electrical wiring in India (Neutral vs Earthing vs Grounding)

[guest_999]

You can do the best earthing possible at home, and it will not work correctly if the earthing at the transformer is not up to the mark. This is what I heard from a proper electrician.

"Real earthing" involves digging a pit in the ground & bury the main earthing wire inside & is meant to protect the home from lightening strikes, static buildups & power surges. Equipment earthing is a bit different but it shouldn't have any relation with transformer.

 

[cranky]

Heisen is correct in this instance.

I talked a bit about this in #7. The ground/earth/neutral reference is from the utility scaffold on which the transformer is mounted. The earth and neutral bonding is done at that point, and after that the neutral carries the reference to your equipment (utility does not supply the earth but references to it, which is the source of your confusion). The ground is your safety net. The voltage difference exists because of how near/far the transformer is from your location, and how good the earthing resistance is - a function of the quality of the poles and how well the transformer is grounded.

The reason that the live line is dangerous is because it is referenced to earth, and humans can bridge the gap. But it is also the safety net for humans touching the live line in the first place. The danger of not having any reference at all is 'float', where untethered power supplies can drift to a dangerously high level above ground, and cause a current to flow anyway, sort of how lightning works but obviously at a much lower level and lower energy - still sufficient to harm or kill humans.

 

[mk76]

How old is the wiring?

Wiring is old. Last changed 10+ years ago

Do all rooms have their own MCBs?

All rooms have their own MCB

The Tester lighting up is common occurrence in India. It may not be right or OK, I am just stating a fact.
However, if the place where the tester lights up and a reliable earth connection show a Voltage difference of 220V, then for sure there's sho

This is common across all sockets. Also it was a direct connection aka no extension board in between

However, if the place where the tester lights up and a reliable earth connection show a Voltage difference of 220V, then for sure there's short.
As for the Electrician, he did what nearly every common Electrician in India does. Change whatever seems suspicious. No per outlet testing. No isolation or equipment testing. etc.
One of the things to do immediately is remove all Three-Pin EXTENSION boards. Also remove the three-Pin adapters that can connect three electrical appliances. Oftentimes, these are faulty.
Then, Isolate Rooms, and start testing Room to Room, and then Outlet to Outlet. You could find some problematic connections.

• I tested without 3 pin extn board. And still get the tester to light up
• I also used a socket tester ( Amicisense Socket Tester ) to get a quick glance of socket status and observe 3 places where earth was open and 2 places where PN was reversed. But the core issue is with 2 pin DC devices leaking current
• Example
  • 6A socket > Belkin 100W GAN charger > USB C port > USB C to C wire > its metal end > lights up tester + metal surface to ground is 100V
  • This is same socket whose PN , NE , EP readings I have shared .

The ground/earth/neutral reference is from the utility scaffold on which the transformer is mounted. The earth and neutral bonding is done at that point, and after that the neutral carries the reference to your equipment (utility does not supply the earth but references to it, which is the source of your confusion).

If I understand correctly, the N-E bonding is to be carried out by the utility company and where the transformer is placed. ?
Additionally can the consumers bond N - E to any earthing earth source .. let's say before the the PN are attached to the electricity meter ?

 

[cranky]

I think a diagram will help here:

The three-phase transformer is not an accurate representation, it's just what the schematic library had to offer.

All currents, including fault currents to earth, will find the path of lowest resistance. Assuming you are touching the appliance (which is assumed to have a live wire shorted to a metal enclosure), the resistance to earth - all the way back to the neutral of the utility transformer output - will need to be lower than your resistance to the same point.

 

[mk76]

First of all lots of thanks @cranky @rsaeon and others ; for your time and efforts for sharing useful info.

All currents, including fault currents to earth, will find the path of lowest resistance. Assuming you are touching the appliance (which is assumed to have a live wire shorted to a metal enclosure), the resistance to earth - all the way back to the neutral of the utility transformer output - will need to be lower than your resistance to the same point.

So what could be the issue here
- Neutral is putting up resistance and thus fault is not going back.
- And NE bond at Transformer is not helping either


And how do we fix this ? Can we bond NE just near home ; which is closer than the transformed ( and before N is attached to meter ) ?

Diverting to the earth is much more effective than sending it back to the transformer. The neutral wire is not designed to handle faults, it's only meant to provide a return path for the current that's utilized. The neutral wire can carry faults back to the transformer, but it's not very effective. Earthing acts as an extinguisher for fault currents.

Earthing is bonded to neutral at only one place, and that is the main distribution box and nowhere else.

 

[cranky]

The bonding you talk about at your home is the earthing rod. Its purpose is to bring the apparent resistance value as close to zero as physically possible. The reduction in resistance from your 3-pin outlet to the main entry board is not sufficient to qualify as a major change, and is half-measures at best.

Multiple ground connections are not an issue, so you can do it from your own flat as well, all the way down into a fresh pit.

Be aware though that in this kind of implementation fault currents will still seek the lowest possible resistance, so there's a rare possibility that other fault currents not generated in your home but sharing the same utility phase, may find their way into that earth and may give rise to strange noise in audio and A/V equipment. We've had this issue with clients who redid their mains wiring with very heavy gauge wire and then complained of noise in their speakers.

Your job is to get every resistor except the last one (YOU) to zero as far as possible, and your body resistance as high as possible - insulating yourself from the floor, for example. this will keep you safe in the case of grounded appliances developing a L-E fault.

This will not solve your tester lighting up or your tingling, FWIW. It will probably lower your N-E voltage to within an acceptable margin, if the utility has done their job properly. For that, you may try reversing the charger polarity to get C4 (shown in one of earlier posts) connected to Neutral instead of Live. It might work, or it might not.

 

[mk76]

This will not solve your tester lighting up or your tingling, FWIW. It will probably lower your N-E voltage to within an acceptable margin, if the utility has done their job properly. For that, you may try reversing the charger polarity to get C4 (shown in one of earlier posts) connected to Neutral instead of Live. It might work, or it might not.

Additionally I will check the charger at some other house/place to rule out any issue with it.

 

[Skyh3ck]

Great thread. Let me add my woes.

Couple of 2-pin DC devices light up the tester bright when touched at metal surface. These include - usb charger, yamaha keyboard and more. Also 100ma RCCB would trip occasionally. To fix, our society electrician got our MCB box + many old rusted MCB changed and removed the RCCB as it used to trip every now and then. He fixed the ground connection. But that did not fix the core issue that we begin with. Understandably he's no good . Raised his hands and said he can't fix it .

Here are few measurements I captured

• Phase to Neutral - 242 V
• Phase to Earth - 247 V
• Neutral to Earth - 9 V
• When I measure AC between the leaking surface and my body it varies between 40-100V ( bare foot )
  • 100W gan charger
    • It's 65W port measures 110V AC from usb C metal and my body
    • It's 15-20W port measures 20V AC
  • Another USB charger 5V 2A output does not leak anything
• Sometimes the current pinches, when the surface touches any soft skin like upper arm or just below elbow. But is barely felt when touched with fingers .

Any idea what could be the issue? And how should I proceed to get it fixed.

i have all my usb charger leaking voltage, need to check earthing, its a great great discussion, one of the main important point

people spend more money on costly electrical applicanes but they dont want to spend little more on proper earhign, very sad
its because mainly all local elctrician who do wiring, they dont know much about earthing, and they do not educate home owner
proper earhing cable would save lot of time and future cost

 

[msvsme]

Please shed light on the new system of earthing using compound instead of using salt and charcoal. Some use gi rod with chemicals inside. And I read that Copper erodes with the added salt.

Would appreciate your knowledge for a permanent maintenance free earthing for my solar and lightning arrestor diy setup.

 

[rsaeon]

The neutral wire fell off the pole the other day, resulting in this:



Two phases went over 300, one phase went down to 120. The electricity workers here don't climb poles after 5pm so I had to wait until 11am the next day for it to be fixed, and I paid Rs 1000 even though this affected an entire block of houses and flats (apparently my neighbours didn't care enough). I'm in an area where the residents don't pay taxes (slums) so we're not prioritized when these things happen.

I switched over one of the smart plugs to the other phase to better understand what was happening (pink line). Blue line is the home lighting inverter — I switched that over to the server ups/inverter so my parents would have reliable power while they were awake and then put it back while they slept then again back after they woke up. I got about four hours of sleep that night because I needed to monitor the cluster (which I needed to keep online because of cyber monday weekend).

This isn't the first time it's happened so now I'm wondering if I should get a neutral pit dug because I lost a lot more than Rs 1000 during those ~17 hours of unreliable power.

This is the work they did (the lower joint is the neutral, the top joints are the three phases):



Despite the less-than-stellar workmanship, their terminology was flawless — "we found the neutral jumper was disconnected, it is now reconnected."

 

[msvsme]

My house uses 0.75sq mm wire to connect from mcb box to outlet earth pin. And thicker wire from mcb box to earthing pit.

Question is, why is the wire so thin? Is it fine? While Phase and Neutral wires are of 1, 1.5, 2.5sqmm.

 

[adder]

The neutral wire fell off the pole the other day, resulting in this:



Two phases went over 300, one phase went down to 120. The electricity workers here don't climb poles after 5pm so I had to wait until 11am the next day for it to be fixed, and I paid Rs 1000 even though this affected an entire block of houses and flats (apparently my neighbours didn't care enough).

Been there, I know your pain. I had 320v, 280v and 100v or something in the phases in dec 2017. It resulted in my Sony lcd failing. The high voltage lasted a full week, no one from the 5 streets the transformer is connected to complained. It took a lot of escalation to finally fix it happened again a month later and there after once every year or so. This happens when the neutral wire or contact area is loose or has carbon deposit after arcing.

This isn't the first time it's happened so now I'm wondering if I should get a neutral pit dug because I lost a lot more than Rs 1000 during those ~17 hours of unreliable power.

I thought of this too at that time. But they said its illegal to do so. Technically the neutral wire is nothing but the ground to the transformer. But even if you dig a neutral second earth pit, your pit will now act as a earthing/neutral for the entire houses and streets the transformer is connected to. That means unwanted electricity flowing from ups/ inverters connected wrongly, lightening, phases shorting due to crow or branches resulting in 460v. So my advise is to either go off grid or keep ask the Electricity Board officials to get their shit in order.

This is the work they did (the lower joint is the neutral, the top joints are the three phases):

Despite the less-than-stellar workmanship, their terminology was flawless — "we found the neutral jumper was disconnected, it is now reconnected."

Sadly it's the same even in Tier 1 cities. These people had the audicty to say the voltage is fine by putting a tester.

If you want to protect your house from a such high voltage spike use a SPD and then connect it to the output of a ELCB/RCBO. Now when the spd gets a voltage above 275v it will dump all the current to earth. This forces the RCBO to trip and also reduces the failure of the SPD. You will off course get lot of tripping each time the voltage goes above 275v. But in my case I put a auto reclosing RCBO that I got from aliexpress before the ban. The Auto reclosing RCBO would automatically moves the mcb lever after a trip and repeated trip will lock it out and will need manual intervention for safety.

I had posted about this before also in some thread.

My house uses 0.75sq mm wire to connect from mcb box to outlet earth pin. And thicker wire from mcb box to earthing pit.

Question is, why is the wire so thin? Is it fine? While Phase and Neutral wires are of 1, 1.5, 2.5sqmm.

Earth needs to have the lowest resistance. As the current and voltage builds up, the resistance of the wire increases and electricity flows in the path of least resistance. So if your body has lower resistance than the earth wire then you will get a lethal frying shock, unless you have elcb/ rcbo/rccd.
So earth wire should be the same size as the live or neutral wire. There is a reason the earth pin is bigger on a 3 pin plug both in 5a and 15a plugs.

 

[rsaeon]

That's brilliant advice, thanks a lot.

Offgrid is the long term goal, but these things happen so often that I think I need some kind of neutral disconnect/changeover at the meter. But it's probably not worth the risk.

One of my UPS was happy with upconverting the 120V to 230V which was a huge relief and it let me keep half of my machines online that night.



I did get a sense of how to better set up the power conditioning appliances I have though. Need to get a stabilizer that can handle >350V, an inverter in wide input or eco mode so that it doesn't trip often then this online ups that I have as the last part of the chain.

Stabilizer will handle high or low voltages, I already have a 5kVA one so maybe add another before this that's rated for higher voltages (this one can handle low voltages fine). Inverter will handle extended power outages, and the ups will handle power cuts/spikes/irregularities.

Gotta put some thought into this.

These people had the audicty to say the voltage is fine by putting a tester.

This exact same thing happened when I called them.