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David Hmingthanmawia
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Join Date: Jun 2010
Posts: 3

Increasing Voltage

07/05/2010 2:50 PM

In one of my projects, voltage between earth and neutral is 0.01volt. When the load is given (ie when lights are in ON position), the voltage between earth and neutral is gradually increasing up to about 25-30volts. Kindly inform me what will be the reasons.

The other case is when neutral from the Main Supply and Residential Earthing is checked by continuity of the Multimeter, it shows some beep sound. It seems to be interconnected. What is the reason? Please inform my problems.
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jack of all trades
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#1

Re: Contractor

07/05/2010 3:23 PM

Given your comments (and the words "contractor" and "project"), I would strongly advise leaving this work to a qualified electrician as you don't seem to understand the basics of the applicable electrical codes and bonded MEN (Multiple Earth Neutral) (or similar, as it varies from country to country) systems which are designed to have the earth and neutral connected at specific points for electrical safety.

Please bear in mind that if this is for a project or job, then your employer (and possibly you too) could be liable for any illegal works, property damage, loss of life (including yours!), etc if an untrained individual such as yourself tries to perform said electrical installation and/or testing.

Can you please provide more information on why you are asking this question (including your country as electrical standards, codes and systems vary from country to country). Alternatively this question has been answered previously on CR4 before (sorry I don't have the link).

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redfred
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#6
In reply to #1

Re: Contractor

07/05/2010 10:18 PM

A very Good Answer Jack. Accurate and very diplomatic.

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Unredundant
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#2

Re: Contractor

07/05/2010 3:23 PM

From what I can understand your check of the earth/neutral bond with a "visual" beep is indicating continuity for a very small amount of current (the multimeter) where in reality there is a faulty earth/neutral bond.

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jack of all trades
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#3
In reply to #2

Re: Contractor

07/05/2010 3:40 PM

In simple terms the continuity test feature of a multimeter injects a small amount of current and gives a corresponding single tone to indicate if there is a low resistance present.

A continuity test alone is not a conclusive test for testing a Neutral-Earth bond as it requires no other voltage potentials or flowing current to be present (which can effect the reading).

The fact the Neutral and Earth are bonded together leads me to believe the installation is likely MEN type (or similar) where the Neutral and Earth are intended to be bonded together at the switchboard (a system that is common throughout many parts of the world including New Zealand), however without knowing what country the installation is in this is purely an educated guess until the original poster provides more information.

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Unredundant
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#4
In reply to #3

Re: Contractor

07/05/2010 4:36 PM

I am in complete agreement with your recommendations and was trying to convey the principles of a multimeter continuity test (although I have not heard of a "visual" beep) and the misapplication.

My efforts to "dumb down" my reply has backfired, as your reply to me indicates.

Had I seen your post before I submitted mine I wouldn't have bothered posting.

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jack of all trades
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#5
In reply to #4

Re: Contractor

07/05/2010 5:44 PM

I thought that may have been the case half-way through writing my response but posted anyway as I thought the extra information may be of benefit for the original poster (especially the second paragraph).

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Joe Sparky
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#8
In reply to #3

Re: Contractor

07/06/2010 6:30 AM

Hi Jack off all trades,

I am in Auckland, Office in East Tamaki, I would like to catch up with you some time.

Cheers

Joe
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jack of all trades
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#9
In reply to #8

Re: Contractor

07/06/2010 3:14 PM

I am in Auckland, Office in East Tamaki

It is such a small world, so am I!

I would like to catch up with you some time

Sounds like a good plan, we can trade contact details via CR4's private message system.

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PWSlack
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#7

Re: Increasing Voltage

07/06/2010 4:22 AM

The voltage between neutral and earth at any instand is a function of conductor size, distance from the supply location and the vector sum of the currents in the three (usually) phase conductors feeding other loads elewhere. Its actual value at any place at any moment is irrelevant.

Earth is there to operate the circuit protective device(s) in the event of a fault.

Please read the Wikipedia article on earthing systems.

If in doubt, consult a qualified electrician.

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LAA_Lucke
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#10
In reply to #7

Re: Increasing Voltage

07/07/2010 5:44 AM

In fact, for this OP, the voltage he is checking (N to Earth) is function to the earth resistance. he is probably checking the earth at a connection point linked to the earth rod(or whatever...) and a neutral wire.

He is having some earth leaks and does not have a proper ELCB on the line or he has a mixed wiring problem whereby a grounding wire has been used as a neutral in his circuit...therefore, any load on the Live Ground will increase the voltage drop and he is checking that voltage drop. This is what I think is happening.... not enough info to guess more than that considering his lack of knowledge in the subject he will be lost unless a course and circuit drawings are involved..?
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jack of all trades (4); Joe Sparky (1); LAA_Lucke (1); PWSlack (1); redfred (1); Unredundant (2)

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