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

[john1911]

Hey guys, I hope everyone is doing well.

Recently, I noticed a faint light in the earthing pin of a socket at home when I checked with a regular electric tester. It only appeared for a short time, and I found it by chance. I checked just one switchboard, so I'm not sure if this was happening in all the boards or if it's isolated. It is not there now.

Spoiler: Sorry for being vague.

I don’t know much about house wiring beyond the basics and best practices, so I’m starting this thread to discuss it and clear up my doubts. I’m not familiar with how the wiring in my home was done. My dad supervised it, and the local electrician did the work. Dad said it was done the same way as other houses in our town. Sorry for the lack of precise information; my knowledge on this topic is quite basic.

After noticing the faint light in the earthing pin (the largest hole at the top in socket), I thought this couldn’t be normal. I called the local electrician, who brought some equipment to check the earthing. I wasn’t there during the check, so I don’t know what he found. He said that the earthing at our home has become weak and advised us to redo it. He mentioned that the value should be less than 1 (I’m not sure if it’s 1 ohm or 10 ohms, as he didn’t specify, and I wasn’t there to ask). Our value was 3.

Dad told me that he always thought earthing and neutral were the same. I asked how many wires come to our house from the transformer, and he said only one (the phase wire). He explained that every house in our town has only a single phase wire coming from the transformer. I then asked where the neutral (the small hole on the left in the socket) and earthing (the large hole at the top of the socket) are connected. He kept referring to the neutral wire as earthing and totally ignored the actual earthing. He said the neutral (small left hole) is connected to the earthing pit (a 10-foot deep hole with a copper rod, etc.). I asked where the top large hole is connected, and he said he wasn’t sure but thinks it’s connected to the same earthing pit. Since we have only one earthing pit at home, I assume both the neutral and earthing are connected to the same pit.

I’ve been reading and watching videos for the past hour, and most sources say that two wires (live/phase and neutral) should come from the transformer. But according to my dad, no house in our town has two wires coming from the transformer.

I know theory often differs from practice. Please help me understand the ideal setup and what’s usually done at our homes? I can’t ask the electricity provider to give us a separate neutral if no other home has it, and anyway, neutrals at transformers are grounded. Does it make a difference? Should we have separate earthing pits for neutral and earthing?

I apologize if anything is unclear or confusing. Please ask for clarification if needed, and I will be happy to elaborate to the best of my knowledge. And thank you for your time.

 

[rsaeon]

For single phase connections, there's one cable coming in from the pole. This cable is called the "service wire."

In that cable are two wires, one live and one neutral. These two wires complete a circuit, or the flow of electricity, from the transformer to your home and back to the transformer.

For three phase connections, there's two cables coming in from the pole, that's four wires in total, three live (one for each phase) and one neutral.

Fun fact: the electricity department is only responsible for getting the wire safely/responsibly to your meter. Everything from the meter and beyond is the home owner's responsibility, including the meter and any damage that might happen to it or fault that may develop with it.

Earthing is a safety measure, a diversion of live electricity in the case of a fault. The fault here would be live wire or voltage somehow making its way to the exterior of an appliance and subsequently making contact with humans/animals.

The earthing connection would divert that live voltage down to the earth, providing a path of very low resistance (compared to your body), so that you wouldn't get electrocuted if you happen to touch that electrified surface of the faulty appliance. Live electricity would just ignore you/your body and choose to flow through the path of least resistance to the earth.

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. A fault current means raw electricity that's not utilized in anyway and is just flowing unhindered where it's not supposed to be flowing, like a short circuit or when the insulation of a wire is broken/cut/degraded and exposed to a conductive surface (like the exterior of an appliance).

Earthing is bonded to neutral at only one place, and that is the main distribution box and nowhere else. This is protection for the rest of the house if a short develops somewhere in the house — that short would trip the MCBs so it's important that earthing and neutral are not joined anywhere except at the main distribution box. Also if you join them in multiple places, you might end up with "ground loops" (one example of a fault) where the earthing "potential" (voltage) is different at different parts of the house and there's no clear path for electricity to flow into the ground in the case of a fault (defeating the purpose of having earthing at all). There's a lot more reasons as to why earth and neutral are bonded at all, but safety is the biggest one.

The voltage measured between earthing and neutral in a socket should be ideally zero, but it's usually under 1 or 2 volts, which is acceptable. Measuring 3 volts between earth and neutral does indicate a problem somewhere, either in the connections between the house and the earthing rod, the bond between earth and neutral, an overloaded neutral wire that's carrying more current than it's rated to (some people erroneously undersize the neutral wire compared to live), or just corrosion in the earthing rod itself (which means earthing needs to be redone).

We've had our earthing redone recently at an eye-watering cost of 20k (we probably overpaid to get it done in a few hours because the taps started electrocuting us). This is because some years ago we were flooded for a few hours and the earthing rod started getting corroded way back then. A new pit was dug and a giant earthing rod/probe was installed (its almost as tall/wide as me):

IS 3043 is a fascinatingly boring read on all things earthing, it was recently revised some years ago: https://archive.org/details/gov.in.is.3043.2018

edited to add: Neutral pits are a thing and they're separate from earthing pits, but you almost certainly have a neutral wire inside the same cable as your live wire — a neutral pit alone cannot handle the return current.

 

[alap4m]

@john1911 Take a second opinion.
It is highly unlikely that ONLY A SINGLE, phase wire, is entering houses WITHOUT the Neutral Wire. There MUST be another Neutral Wire which offers a return path for the Electricity.
Check your Electrical Meter. It should have FOUR Wires. Two coming from a Nearby MAIN connection (In buildings it is usually called a Bus Bar. For Standalone houses nearby electricity poles offer connection points), and TWO wires ENTERING the House.
If THIS is NOT the case, it would be wise to complain to the Local Electricity Distribution Agency or take the complaint to higher authorities.
Coming to the EARTHING glowing. This is a Serious concern as electricity has found its way to the Earthing and MUST be separated.
An experienced Electrician should be able to find Where the fault lies and ensure proper separation.
Local Electricians are quite arrogant and ignorant. And Electricity is dangerous, especially in wet areas like Kitchen, Toilets, and Bathrooms.

 

[john1911]

For single phase connections, there's one cable coming in from the pole. This cable is called the "service wire."

In that cable are two wires, one live and one neutral. These two wires complete a circuit, or the flow of electricity, from the transformer to your home and back to the transformer.

For three phase connections, there's two cables coming in from the pole, that's four wires in total, three live (one for each phase) and one neutral.

Fun fact: the electricity department is only responsible for getting the wire safely/responsibly to your meter. Everything from the meter and beyond is the home owner's responsibility, including the meter and any damage that might happen to it or fault that may develop with it.

Earthing is a safety measure, a diversion of live electricity in the case of a fault. The fault here would be live wire or voltage somehow making its way to the exterior of an appliance and subsequently making contact with humans/animals.

The earthing connection would divert that live voltage down to the earth, providing a path of very low resistance (compared to your body), so that you wouldn't get electrocuted if you happen to touch that electrified surface of the faulty appliance. Live electricity would just ignore you/your body and choose to flow through the path of least resistance to the earth.

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. A fault current means raw electricity that's not utilized in anyway and is just flowing unhindered where it's not supposed to be flowing, like a short circuit or when the insulation of a wire is broken/cut/degraded and exposed to a conductive surface (like the exterior of an appliance).

Earthing is bonded to neutral at only one place, and that is the main distribution box and nowhere else. This is protection for the rest of the house if a short develops somewhere in the house — that short would trip the MCBs so it's important that earthing and neutral are not joined anywhere except at the main distribution box. Also if you join them in multiple places, you might end up with "ground loops" (one example of a fault) where the earthing "potential" (voltage) is different at different parts of the house and there's no clear path for electricity to flow into the ground in the case of a fault (defeating the purpose of having earthing at all). There's a lot more reasons as to why earth and neutral are bonded at all, but safety is the biggest one.

The voltage measured between earthing and neutral in a socket should be ideally zero, but it's usually under 1 or 2 volts, which is acceptable. Measuring 3 volts between earth and neutral does indicate a problem somewhere, either in the connections between the house and the earthing rod, the bond between earth and neutral, an overloaded neutral wire that's carrying more current than it's rated to (some people erroneously undersize the neutral wire compared to live), or just corrosion in the earthing rod itself (which means earthing needs to be redone).

We've had our earthing redone recently at an eye-watering cost of 20k (we probably overpaid to get it done in a few hours because the taps started electrocuting us). This is because some years ago we were flooded for a few hours and the earthing rod started getting corroded way back then. A new pit was dug and a giant earthing rod/probe was installed (its almost as tall/wide as me):

View attachment 206773

IS 3043 is a fascinatingly boring read on all things earthing, it was recently revised some years ago: https://archive.org/details/gov.in.is.3043.2018

edited to add: Neutral pits are a thing and they're separate from earthing pits, but you almost certainly have a neutral wire inside the same cable as your live wire — a neutral pit alone cannot handle the return current.

Thanks for the detailed information. Much appreciated.

I will go and check the wires (from transformer to home) and electricity meter today or tomorrow.

@john1911 Take a second opinion.
It is highly unlikely that ONLY A SINGLE, phase wire, is entering houses WITHOUT the Neutral Wire. There MUST be another Neutral Wire which offers a return path for the Electricity.
Check your Electrical Meter. It should have FOUR Wires. Two coming from a Nearby MAIN connection (In buildings it is usually called a Bus Bar. For Standalone houses nearby electricity poles offer connection points), and TWO wires ENTERING the House.
If THIS is NOT the case, it would be wise to complain to the Local Electricity Distribution Agency or take the complaint to higher authorities.
Coming to the EARTHING glowing. This is a Serious concern as electricity has found its way to the Earthing and MUST be separated.
An experienced Electrician should be able to find Where the fault lies and ensure proper separation.
Local Electricians are quite arrogant and ignorant. And Electricity is dangerous, especially in wet areas like Kitchen, Toilets, and Bathrooms.

Thanks for the reply, I'll check the wires and meters.

 

[john1911]

Hi guys.

We redid our wiring some ~ 15 or so years ago. Prior to that, we had a single wire (Live/Phase) coming from the transformer and we had neutral hole in socket connected to our earthing pit. There was no earthing in the house back then. Dad remembered the earlier details.

We rewired everything ~ 15 years ago and since then we have 2 wires (Live/Phase and Neutral) coming from the transformer. The same earthing-pit (which was earlier connected to the neutral hole in socket) is now connected to earthing hole in the socket.

We will be redoing the earthing-pit pretty soon.

Thanks for the help

 

[alap4m]

Hi guys.

We redid our wiring some ~ 15 or so years ago. Prior to that, we had a single wire (Live/Phase) coming from the transformer and we had neutral hole in socket connected to our earthing pit. There was no earthing in the house back then. Dad remembered the earlier details.

We rewired everything ~ 15 years ago and since then we have 2 wires (Live/Phase and Neutral) coming from the transformer. The same earthing-pit (which was earlier connected to the neutral hole in socket) is now connected to earthing hole in the socket.

We will be redoing the earthing-pit pretty soon.

Thanks for the help

This was an absolutely horrific type of wiring. Good that your house now has TWO wires to complete the circuit.
Do not hold back on the Earthing pit. Put ample coal and a large copper plate along with salt. There are several videos that guide how to create an earthing pit.
Additionally, connect this pit to an earthing rod and fix the same on the roof. This will help protect your standalone dwelling from Lightning strikes as well.
As and added precaution, recheck all the wiring inside the house and tighten connections and screws.
If there are old wires, it would be wise to replace them with newer multistrand wires for better electrical conductivity.

 

[cranky]

The voltage measured between earthing and neutral in a socket should be ideally zero,

Excellent post, I must say

I believe up to 4 volts measured with a high impedance meter is acceptable. The actual resistance must be below around 5 ohms, specifically allowing for highrises to be able to meet spec - a building two hundred feet tall cannot meet the 1 ohm spec at all. Human body model is to the order of 750 ohms to about 2kohms. We're in the process of actually designing a mains conditioner with isolated outputs and had to do a ton of reading on the subject The allowed fault current is 30mA on the live output, which is what most domestic RCCBs are targeted at.

Taken from: https://researchspace.auckland.ac.n...0/electric_shock_2.pdf?sequence=1&isAllowed=y

Another link that might be useful: https://intertech.com.co/earth-resistance-values-in-india/

Now the issue is the testing voltage. Handheld meters are not very useful because they run off a 9V battery, with some lower end models running off two AA cells. There just isn't enough voltage/current to properly test resistance and indeed, all resistors/resistances have voltage coefficient, which is a change in resistance with the magnitude of applied voltage. A proper earth testing meter is needed, which runs a test current of 30-200mA at a dozens of volts to ensure the earth protection holds up. Here's another nice link for those interested (read the follow-on links):

Earth Ground Testers | Digital Earth Resistance Testers

Built to withstand an entire spectrum of ground testing methods, Fluke's family of earth ground testers have been designed to be accurate, safe and easy to use. Browse our top selling 1623-2 GEO earth ground resistance meter, 1625-2 GEO earth ground tester and the 1630 ground resistance meter today.

www.fluke.com

To the OP, the wire up to the transformer from the substation carries only three phases. The earth (the brown and blue mass we live on) carries the "neutral". The transformer has four terminals in, the fourth is grounded through the utility scaffold and the output has four nodes, one neutral and three phases. Post #2 explains the rest, the confusion about "only live" comes from seeing only three wires on the grid pylons, each for one phase. In your residence, the neutral is supplied by the utility. This you can verify by looking at the meter. You will notice the meter has four connection posts, one each for live and neutral in and out. You cannot measure power using only one phase connection, at least not that I know of.

Earthing is your responsibility but if you already have an earthing pit, you're probably OK (as is your 3 ohm resistance, that's fine too if your guy is using a handheld meter to test). If you're very worried, use a RCCB for protecting outlets that have high incidence of human contact. RCCBs are a little fussy and can trip often, but are also very good insurance because they don't depend on actually having an earth connection like an ELCB.

 

[ssslayer]

What happens if there is no neutral cable running to distribution transformer and the neutral and earth are connected to same point and same pit?

 

[cranky]

This was the way domestic supplies were wired until the 50s. The transformer did not fully isolate the 4kV from the secondary, just stepped it down (autoformer) with a tap and depended on the conduction of ground. This wastes a ton of power due to the winding resistance and the resistance of the actual ground.

At the purely technical level. Both earth and neutral are at 0V relative to the phase wire. But their role and current capacity is different, and there is no reason for any utility to not provide a neutral line. I'm not aware of any utility that doesn't do so. Is this still a thing? If your domestic electrician chooses not to accept the utility neutral and runs everything out of a pit, be aware that your voltage will fluctuate to a much greater extent because for very short distances copper has a lower resistance than the ground at 230V.

What is more common is the lazy electrician's method of avoiding the pit entirely and using the neutral for earth wiring. This results in an apparently lower resistance when measured, but is not "true" earthing and large fault currents will elevate the fake earthing to close to live voltages. Even slight leakage currents into the ground wire (common in most switched supplies which use the earth to drain common-mode noise) will cause enough voltage on the neutral line to seriously injure anyone in contact with the metal casing of an appliance.

 

[alap4m]

@cranky Excellent point about the RCCB. They are indeed excellent at protecting Humans and Animals from Electricity leakage and Shocks.
However, they are "TOO" Good for Indian Electricity and Wiring. As you rightly pointed out, RCCB trips often, but it is due to their higher sensitivity and design.
Hence, even experienced electricians do not usually recommend using RCCB.
Conventional MCBs are more than adequate at stopping an electric short-circuit and preventing any overheating of wires. But they do not protect humans from electrocution when they accidentally touch a live wire or an exposed contact with the metal casing of an appliance.

 

[cranky]

True, therefore I recommend using it on specific outlets and areas instead of whole-house where the variables are too many. Additionally, for new installations with proper wiring, it shouldn't be too much of a problem if you're not running ring circuits, which is the norm for most existing installations 15 years and older. I have local MCBs for each main board in my house (main board meaning those running sensitive devices, or high-current ones) along with separate circuit breakers for each room that doesn't have a dedicated breaker. Unfortunately my house also has ring circuit wiring, which makes using a RCCB tricky. Therefore the conditioner we are building, which provides shock protection to two high current outlets to which one can connect amplifiers and receivers, for example.

 

[guest_999]

Therefore the conditioner we are building, which provides shock protection to two high current outlets to which one can connect amplifiers and receivers, for example.

I am assuming those are not typical audio video amplifiers & receivers as those don't need "high current" I think.

 

[cranky]

On a continuous basis, no. But even some of the larger AVRs will require about 4-5A at startup. High current in this instance is "higher" than line level devices. The non-isolated outputs have a capacity of 10A combined, which is sufficient for all but the most extreme setups.

However, Class A amps like the ones we build and sell are not recommended to be connected to any sort of conditioner (including this one) due to the higher impedance imposed by the filters, unless as a last resort. It has never been needed or perceived to be a problem in the last dozen or so years of our history (including in tier 3 towns).