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Anonymous Poster #1

Earthing

05/17/2017 9:03 AM

please can anyone tell me on how to reduce resistance to the earth to less than one ohms, am getting higher resistance like 8 ohms on earthing system

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#1

Re: earthing

05/17/2017 9:30 AM

If you drill until you reach a metallic ore vein or the Earth's nickle, iron core (whichever comes first) you will greatly reduce your impedance to earth.

This smart ass response was made because you do not give us any information at all on where this installation is supposed to reside or how you've already tried to achieve a good earth connection. (A 1 cm long exposure, 1 mm diameter solid copper wire stuck into the soil will not provide a good earth.) Local geology makes all the difference in the magnitude of your local earthing value. Long Island NY is an enormous terminal moraine. This island was made from the the top soil, clay and grit of New England left when the ice age glaciers receded. Sand and clay do not conduct very well but I and my neighbor have the same earthing problems.

Therefore your local earthing standard techniques are what you should follow. If your application requires a truly exceptionally low magnitude earth connection (RF broadcast or detection?) for your area then select the approved local earthing technique that provides the largest surface area that is in contact with soil. Unfortunately often the largest area techniques produce the least reliable connection due to corrosion.

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#2
In reply to #1

Re: earthing

05/17/2017 10:56 AM

Have everyone on site urinate in that area for two weeks. That should solve it.

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#19
In reply to #2

Re: earthing

05/18/2017 2:27 PM

If there is very much voltage on the ground wire can I pee in a bottle then pour it on the ground electrode? The direct method my hurt. - Circuit Breaker

P.S. I don't want the ground current to open this Circuit Breaker!

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#20
In reply to #19

Re: earthing

05/18/2017 3:08 PM

It might not open the circuit breaker, but it might open something else! Breaker breaker 1-9r, I have an issue here, send a bus, and a large wad of gauze! And send three cases of Charmin!

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#21
In reply to #19

Re: earthing

05/18/2017 3:32 PM

No worry. The Mythbusters already covered this topic.

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#5
In reply to #1

Re: earthing

05/17/2017 11:51 AM

Really! Previously I had one GA for my reply but now some spineless troll negated that with no explanation. I guess the only thing applauded at CR4 today are bodily functions and crass jokes. No wonder people are leaving CR4.

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#6
In reply to #5

Re: earthing

05/17/2017 12:10 PM

Why are you on a tear? I gave you a GA! Why is everyone so pissy foul tempered today? Bad grounding?

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#9
In reply to #1

Re: earthing

05/17/2017 3:36 PM

The location is Ogun state Nigeria and the length of the rod to the earth is 1.8mm

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#11
In reply to #9

Re: earthing

05/17/2017 5:57 PM

No wonder the resistance is high, if the length of the rod (to the earth) is 1.8 mm. That represents a pretty big spark gap potential required for grounding.

You might try actually sticking that in the ground next time.

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#3

Re: Earthing

05/17/2017 10:57 AM

There have been many posts on this topic. Use the search feature to find what you need.

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#4

Re: Earthing

05/17/2017 11:38 AM

I'd use more urine water until you come up with more details.

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#22
In reply to #4

Re: Earthing

05/18/2017 4:50 PM

Just don't take it away...

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#7

Re: Earthing

05/17/2017 12:50 PM

"... how to reduce resistance to the earth ..." Using your own question and using the search box located above, results in at least four pages of threads on this very subject >CLICK HERE< Or using the term "earth grounding" results in ten pages of threads on this subject >CLICK HERE< Google search has 36,000,000 results >CLICK HERE<

As Redfred said in his #1 post, we have no idea where you're at in this world or the geology of the soil, nor what attempts that have made to resolve your problems. It"s time for you to do your own homework.

GA Redfred

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#8

Re: Earthing

05/17/2017 1:32 PM

This has been discussed before in this forum. Treat the soil to increase its conductivity and increase the surface area between the copper rods and the soil, for example, by adding more rods.

http://constructionmanuals.tpub.com/14026/css/Figure-3-7-Methods-of-soil-treatment-for-lowering-of-ground-resistance-73.htm

http://cr4.globalspec.com/thread/28766/How-to-Reduce-the-Earthing-Resistance

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#10

Re: Earthing

05/17/2017 4:04 PM

Never mind the absolute value: one needs to show by calculation that the circuit protective device(s) will operate correctly and safely in the event of a fault. If that calculation says "no" then don't energise it until the resistance is lowered below the value that will operate the device(s).

Practical methods of achieving this can be found in earlier threads.

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#12

Re: Earthing

05/17/2017 6:08 PM

What method are you using to arrive at the 8 ohm number? Are you looking for EMP protection or lightning?

There is a book "Getting Down to Earth" that will give you a basic understanding of what is involved. It is available in .pdf format from several sites on line. Depending upon your objective, your local power company, or certified radio tower contractor can help.

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#14
In reply to #12

Re: Earthing

05/18/2017 8:37 AM

SEND ME THE BOOK,

THANKS

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#13

Re: Earthing

05/18/2017 1:14 AM

Pour Salt water on the soil around the ground rod. Any salts mixed with water will provide a conduction path to a greater surface area of the Earth and give you a lower resistance to conductance and discharge of the applied voltages and electric currents seeking ground potential. Saturate the soil (Earth) around your grounding rod system with mineral salts and water and you will lower your ohms to ground. You will have to maintain saturation so long as you use the system as a low ohms ground terminal.

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#15
In reply to #13

Re: Earthing

05/18/2017 9:23 AM

I suspect he first needs to actually insert the ground rod into the ground. You might be surprised how inept some are.

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#16

Re: Earthing

05/18/2017 11:21 AM

This is highly dependent on how you make the measurement. If all of your connections have been verified good, then the only way to lower the resistance is to increase the surface area of the electrode-to-ground on both/either the system and/or the meter. If the meter-to-ground connection is faulty, then you'll get a faulty reading.

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#17

Re: Earthing

05/18/2017 11:46 AM

BRITISH STANDARD BS 7430:2011

A.2 Legislation

The Electricity Supply Regulations (replaced by The Electricity Safety, Quality and Continuity Regulations in 2002) required that where in a substation the HV equipment earth and the LV neutral earth were common, that the resistance to earth has to not exceed 1 Ω. For most substations this value was provided by the un-insulated protective sheaths of the older types of cables in use and was normally sufficient to lower the impedance of these cable sheaths to ensure sufficiently low earth potential rise (EPR) for general combination of HV and LV earth systems even with very high earth-fault current. However this simple requirement is no longer adequate.

Regulation 8(2) of The ESQCR [1] requires that in respect of any high-voltage installation, the earthing has to be designed, installed and maintained so as to prevent danger in any low-voltage network occurring as a result of any fault in the high-voltage network. The advice in the Guidance on the ESQCR [1] is:

The current advice of the Health and Safety Executive is that touch voltages should not exceed curve the recommendations of BS EN 50522, National Annex NA.2.

What do you have to do it is to calculate the touch voltage as per:

BS 7430 9.6.2 Calculation of ground surface potentials or

EN 50522/2011 Annex A Method of calculating permissible touch voltages and to compare this with permissible voltage as fault duration function from EN 50522/2011 Annex B.

So this it is now close to IEEE 80/2013

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#18

Re: Earthing

05/18/2017 12:48 PM
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#23

Re: Earthing

05/22/2017 6:28 PM

Something I forgot.... On systems that might not be to code, the size/length of all ground-wires to the actual electrode might be inadequate. Make sure that you don't have a couple miles of 28ga wire as the only path to the electrode. You can add more electrodes/point-of-entry to ground to shorten the distance to ground, etc.

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