My earthing is screwed
- Thread starter Love4sound
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arunkvivek
Well-Known Member
Been there done that.. it sounds so mean but nothing can beat the joy of a wicked " I told you so".
Long back, in 83 I worked at Bajaj House, Nehru Place, and we got a DCM Tandy PC. It had a warranty of 3 months and it failed 11 times. Later we found out, that building had no earthing (huge voltage between neutral and earth). As a temporary arrangement, we connected our earthing pin to the taps in the toilet ... it worked beautifully.
keith_correa
Well-Known Member
With me? Yes! Thanks for asking.
Hassan Khani
Active Member
If your measured voltage is 230v across Line and Neutral, but different across Earth and Line then it should be Earthing issue only. Also you have a high voltage potential between Earth and Neutral. If the neutral is faulty (carrying some voltage) then the potential difference between Line and Neutral won't be 230v.
Love4sound
Well-Known Member
I suspect neutral line to be the issue. Cause when there is a power cut and running on inverter the voltage between neutral and earth is 0 and max it reaches is 1.5v. The potential difference between neutral and line is around 240-246 but when there is a power cut and with inverter line it’s 225-230v for both neutral-line and neutral-earth. Loot at all three lights glowing when the plug point is switched off. When it’s in inverter line during a power cut the lights won’t glow unless it switch it on.
Nope
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In all practical situations what I have observed is this. Let's say L-N voltage is 230 V. N-G is 3V (which is normal), then L-G is usually at 227V. This is if the earthing is good.
From the distribution xfer to home, there is always some losses and N-G is never 0V. Upto 3 to 5 V is allowed.
Various countries follow different types of connections. In India we have neutral line earthed at the xfer end and in the US it's done at the house itself.
Even there is variation in how the line is drawn on the poles too. In Karnataka, both the live and neutral wires are tied to the insulators on each pole, where as in Kerala only the live wires are tied to insulators. Neutral wires are directly tied to the metal anglers on the pole and that would act as some kind of earthing too. I am really clueless about the way EBs do it. Searched online about the pros and cons but could not get much info about it so far.
Love4sound
Well-Known Member
So I have been monitoring for the last two days. At random times the N-E voltage drops and is stable between 3.5-6 volts for about 2-3 minutes.Based on this pattern can I assume it’s the neutral line to be faulty? Cause of its cause of earthing won’t the high voltage between N-E be always high?
Love4sound
Well-Known Member
Yeah all discussions on net are based on ideal conditions. I asked my mom's help as she is working in an hospital where they have qualified electricians as well as engineers on contract to maintain their heavy equipment's and the generators.Hopefully we find the root cause and fix it
What is measured values of:
1/ Live to Neutral?
2/ Live to Earth?
They should be roughly same.
We had a similar issue in the recent past. I had the same MX line fault detector happily glowing (some times all 3 lights) and E-N showing varying voltages during various times of the day - after running around my electrician/ EB here, I began eliminating each point in the house and you wont believe found one old tube light to be the culprit! When it is switched ON, all the lights glow in the MX and when off its fine (only last 2 glow). So removed it and replaced with a bulb. Not sure if it helps you but worth a try to eliminate each component.
Love4sound
Well-Known Member
Yeah but my case L-N is 235-240 and L-E is 255-260 when N-E is fluctuating between 20-30V
Well i have switched off the main power supply from the common junction box and checked the N-E directly and the voltage is still high.But if N is the problem the above case in any of the apartment might be the root cause as well. It may not be a tube light but some other device or wiring
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Very true. One way to eliminate is to check 'late' in the night - when most of the apartment residents switch off most of the devices.
Love4sound
Well-Known Member
So is this normal? This is screenshot from a video of monitoring the N-G. So it’s at 23v but when I turn on and off the fan switch in the same board the voltage between N-G spikes 300v-1500V. As the v reading is 600V max in the multimeter it shows 300,560 and for a brief second shows 900 or 1500v and goes to 1 as it’s beyond 600V.
Night is high most of the time. 15-40V
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Fan is an inductive load. When you switch on or off, it will generate high transient voltage. Do you have a table or a pedestal fan? Can you connect it to any 3/2 pin socket on the same board and see what happens when you switch on/off? That will eliminate any issue that it is just the ceiling fan that is causing the problem.
EDIT: Do you have a heavy duty water pump in the building. Check the N-E voltage when it is running and when it is switched off.
Love4sound
Well-Known Member
Well i am bored trying so many things. Have asked an electrician to come tomorrow to do all the testing.
Love4sound
Well-Known Member
Today another electrician visited. First test he did was use my multimeter to check if earth and neutral are looped in the main junction box. This test fried my multimeter. Next they removed all the earth wires connected to grounding terminals and tried the conventional bulb test. So my apartments had 8 earth wires which where all unplugged and pulled out. One wire had severe damage and the outer region was chewed leaving the copper strands exposed. Next he connected the neutral to one end of the bulb and tested the other end connecting to all the 8 terminals of the ground wires for my apartments. Out of these 8 five of them are for each apartments and remaining 3 must be for lift,motor and common line.The normal results should be the bulb should not glow when connecting with neutral and ground but when connecting to 4 of the ground wires the bulb glowed not to full potential but very mildly which indicates there is stray voltage between those ground lines. Solution suggested is to install a separate earthing for my house or we need to remove the junction box involving eb and check the wiring behind to isolate any further damage with neutral and earth wiring. Your thoughts?
I don't know what he did to fry the multimeter. Most probably he had selector in wrong position. Sad.
If I understand it correctly, he disconnected the earthing from from each apartment coming to the earthing strip at the ground level. Then he connected one probe of the bulb to the main neutral wire and checked earthing wire coming out of each apartment using the other probe. In that case there was no wire going to the ground right? It's just an wire coming out of each apartment,which is not connected to earthing.
In that case bulb should not glow at all as there is a open circuit unless there is leakage from live wire to the body of the appliances. It looks like three is leakage in 4 houses. One way to check is turn of the mains to those 4 houses and check again.
Did you check the color of copper wires while disconnecting. If there was huge leakage, the wire gets charred and brittle.
If you have option to get a separate earthing done for your apartment, that's a better option in my opinion. You will be saved from such stray leakage from other people's appliances.
If I understand it correctly, he disconnected the earthing from from each apartment coming to the earthing strip at the ground level. Then he connected one probe of the bulb to the main neutral wire and checked earthing wire coming out of each apartment using the other probe. In that case there was no wire going to the ground right? It's just an wire coming out of each apartment,which is not connected to earthing.
In that case bulb should not glow at all as there is a open circuit unless there is leakage from live wire to the body of the appliances. It looks like three is leakage in 4 houses. One way to check is turn of the mains to those 4 houses and check again.
Did you check the color of copper wires while disconnecting. If there was huge leakage, the wire gets charred and brittle.
If you have option to get a separate earthing done for your apartment, that's a better option in my opinion. You will be saved from such stray leakage from other people's appliances.
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