How to Reduce the Earthing Resistance

Do you have a 6 ohm ground resistance reading or a 60 ohm reading? Don't understand why they insist on 21 ohms. Nothing magic about that number. You can install additional ground rods.

Yeah internetionally 21 ohm maximum was no problem but here in dubai we have authority guidelines to follow and they have their own regulations and in earthing resisitance their regulation states that upto 1 ohm maXIMUM ONLY WAS allowed and we the contractor side must meet that at any risk or we will not get thwe approval, i know that adding earth rod will lower it but im asking for different solution beside adding another rod....,

My friend i am sharing my hands on experience you can use bentonite in addition to common salt and charcoal to improve earth Resistance values it may sound funny But its true i have used Cow dung to fill up the earth pit and watered the earth pit over night,next day when the earth Resistance was measured it was less than 1 Ohm but cow dung works only for a day or two But Bentonite works well you need to water your earth pits time to time in fact i had fixed piping system with solenoid operated valve at each earth pit and timer to insure better earth Resistance to keeping safety of men as well as electrical equipment

good luck

crm

Yeah internetionally 21 ohm maximum was no problem but here in dubai we have authority guidelines to follow and they have their own regulations and in earthing resisitance their regulation states that upto 1 ohm maXIMUM ONLY WAS allowed and we the contractor side must meet that at any risk or we will not get thwe approval, i know that adding earth rod will lower it but im asking for different solution beside adding another rod.... because we already cut the thread of the last rod so connection was not pssible anyway i only need 1 ohm more down so this was not that hard do you know any chemical that i can put on copper to lewer the reading of ohmeter....?

Upper limit is 21Ohms, and you are getting 6 Ohms

Where is the problem? So long you are below 21 Ohms There should be no problem.

sorryi mweant i need only 5 ohm more down not 1 ohm

Chemicals may instantaneously give you the impedance you desire to "pass" a test but they will not stand the test of time. Do the job properly & add more electrodes according to the local rules of your energy authority. Are you talking about Earth Fault Loop impedance or is the impedance measured from the Distribution Board to the earth electrode?

In Australia we often have a problem with electric stock fences because of the dryness of the ground. To reduce the resistance we dig a hole to put the earth stake into and back fill it with a product called bentonite.

Bentonite is a natural clay which either has a high salt content or has it added to it. The salt attracts moisture and the clay holds it there. The result is that if the cow touches the fence it gets an electric shock because of the quality of the earth contact. (which seems to be what you need) Otherwise an additional wire is required that the cow has to form a bridge to get the deserved shock.

I don't know if you can get bentonite but you may be able to improvise by using lots of salt and some other form of local clay.

Another way of improving you earth contact is to use a weld mesh earth mat buried at a suitable depth. this gives you a bigger surface area but does not solve the dry ground d problem.

Between the two options you should be able to pass the test.

BAB

Considering that the soil is sandy.keeping it wet would be difficult unless you make a pit with clay in it and keep it wet.There are other cheap hygroscopic materials that you can use like sodium chloride (common salt),sodium hydroxide,sodium sulphate...

I used to work in a paper plant that produced sodium chloride as a by product from their coating color effluent treatment and they would put all of that salt in their earthing pit!

By using Such Salts (Chemicals) would corrode the Earth rod in a long term? Weather you have seen the condition of the earth rod & how does the earth rod resembles at present.

Actually, I don't get what you mean by "6 ohms"... Is this taken during your soil resistivity test?

The IEEE80 shows that 2 to 5 ohms is excellent soil resistance for grounding system. Since, you have the problem of 1 ohm, you can not use copper zinc powder to lower the resistance due to 500mm of soil is left behind from 6M. The only thing you can do is add another copper rod to make 9M deep and try to test it again, I'm sure you will get less than 5 ohms. I'm just wondering, why you are making hole of 20 feet (6M) depth and 6 inch dia. Since you can/may pound it the copper rod (20mm dia) direct to earth?

The requirement of Baladiyah of below 21 ohms is only a guide to make sure that the grounding system network works because this is being use for System Protection Network System of the Power Plant.

The 2 to 5 ohms or lower resistance is excellent and accordance with IEEE 80 Standard.

Eren

I agree with ereneduarte its the right approch you need to do your home work are you shure the earth conducter size has been calculted and right size of conducter is used how did you mesure the earth resistence with two probe or three probe instrument.

if you have right size conductor then the use of Bentonite etc can be looked into

crm

i guess you mean 4 pin wenner method for soil resistivity (as per IEEE 81) or 3 pin pit resistance test. These are two different tests for different purposes.

o yes, bentonite does offer solution but temporary. Once it cracks in high temperature, its effectiveness is over. Kindly refer IEEE 80-2000 clause 14.5.b, it clearly states this drawback.

Adding another copper rod to make 9M deep is good but what if in my case the surrounding area is all rock, and you'd have to travel miles to get anything near normal soil.

As an engineer I use the following

Electrode or Pipe or/and plate. These alternates offer different area for dispeating the fault current as they have larger surface area. Imagine if you were sweating, if I offer you a newspaper piece to wipe that sweat instead of facial tissue paper. The capacity of this mediam is different than that of facial tissue. Hence the result is accordingly.

Similarly, If the soil around the electrode is suitably receptive, it reduces the depth required for electrode. And there are ways to make soil more receiptive permanantly

Life2k

I have commented on how you reduce the soil resistance.

There are many advices on how to reduce it, but this may put you in trouble.

If you have time, please go to IEEE80 and let yourself familiar about this.

"Adding artificial chemical and compound just to lower the resistance is a uncommon practice, especially for the substations"

These artificial chemical and compound will decipate underground, mostly in dry area, which once in a while rain water seeped and washed them out of potential area. if this will happen, more damages may occurred.

Recommend:

Just add more grounding rod.

IEEE 80-2000 clause 14.5.d recommends artificial treatment to achieve permanent earthing & there are such compounds which do not get washed away by rain. Not only such compound drops the levels of resistivity but also retains that level for years. Yes, its almost dream come true for any electrical engineer.

As per IEEE 142, three factors that influence the soil resistivity & make it variable, are:

1. Ionisation

2. Moisture

3. Temperature

Your design is invalid once these factors change due to natural process or DEWATERING in neighbouring site.

By use of such permanent earthing material, one can freeze the soil resistivity.

Earthing is interesting subject of science.

I think we can be of help to this question. Duval Messien France has a Miracle Compound called TEREC+ which can bring down soil resistivity by 85-95% of its original value and retain that value for 10 years, maintenance free. Perfect for dry hot climates and dry rocky or sandy soils. It can also be used to recharge old earthpits. It is mentioned in IEEE document Std 80-2000, 14.5 d),where it is recommended over Bentonite. TEREC+ creates easy conduction,spreads salts evenly, absorbs moisture from the soil & can retain it by expanding 18-20 times in water retention to release it slowly when required. It diffuses into soil pores and creates conductive silicate roots, enlarging conductive zone of the earthpit. Having the same PH value as water, it is completely harmless to grass, plants etc. This has been uses in more than 1 million installations all over the world including nuclear & military installations, petrol refineries, airports etc. but has only recently been put on the commercial market. Please get in touch with me if you feel you would like to tryit out. Available in the UAE. S. Bakshi

How can i apply it? and where can i purchase yhis terec+1 and can you please tell me how much it costs?

Terec+ is aviliable in India & Dubai.

Visit www.sgihouse.com

Eshwar.N

09341053117

unfortunately we are not getting through your site. we need TEREC+ for our earth pits in a rocky area in Rajasthan

I guess you can call them up at 050-6268016 and find all u need to. Good luck.

You get it in UAE. Call on 050-455 2625.

Respected sir

I Mr. kiran kumar R.S, working in KAYNES TECHNOLOGY,as a maintenance engineer. can you please assist me construction and maintenance of earth pits (value should be below 1 ohm ie. 0.5 to 1 ohm)

Thanking you

Kiran kumar R.S.

Hi.All.Ariel here in Kuwait...Terec+ is an effective chemical to lower down the earth resistance.Peresently we tested one project here it's 270 omhs.But when we applied 5 kg.Terec+mix with equal amount of clean water htne pour at the pit.We got 5-8 omhs.average on all 56 pits.my email:ariel@manasir.net

Hi Arial,

This is interesting info. I used TEREC on my project for 336 ohms And get it down to 0.8 ohms.

Good Luck.

Hi

I am based in dubai.

I need to understand as to what is the standard method of making an earth pit from transformer for multistoreyed projects.

Is there a standard procedure for calculating cu rod diameter, depth of pit and materials to be used.

and what would be the most efficient method of testing by us, before we call local authorities for inspection.

Thanks

rushhour1234 at gmail dot com

Hey Rush hour.... No more rush hour in Dubai roads anymore...right?

Anyway, back to the point, Most authorities ask for pit resistance to be below 1 ohms for all electrical pits.

If you have achieved that, call them right away. Its tricky sometimes though. I had once a project where we got the values so we called for inspection. But they don;t come immediately ie you get a date of inspection on a later date. When they came to check, the resistance has gone up to 2.3Ω It was a big showdown.

Whats your project story?

Life2k

Hello,

This seems really a magic but can you tell me how to use it. Thanx

Use of TEREC is simple. Mix equal quantity of water with TEREC. For example 5 kg TEREC mixed with 5 liters of water.

But more important is to know how much TEREC to use. It depends on how is the soil resistivity. If it is very high resistivity, a design calculation needs to be done.

Life2k

Hi all, I am shafeeq

The earth resistance could be reduced by increasing the surface area of contact of electrode with the soil. Instead of Pipe electrode, C.I plate electrode of 1m wide be used and the pit be filled by normal soil mixed with original soil including stimulants charcoal, salt, etc.

Bentonite solution normally lasts short time. Addition of one more electrode normally reduces the earth grid value by half. This method will be economical.

Can anyone let me know if TEREC+ is available in the UK?

Your advise is so apt & practical. But salt does not remain for much long either. Once moisture is gone, earth pit ionisation is dropped as well. Resistivity shoots up. Simple.

I am working on the earthing of a gas power station,when the resistivity test was done some years ago it was laterite that was present in the chosen location.later on the location was sand filled with white sharp sand and now i am looking for the best possible way to reduce the soil resistance.What i have in mind is to add more rods in parallel,but, my big question is how to add them in parallel and how do i knw how many rods(test wells) i need to add to make up and get the required resistance i want.presently i have not gotten to this level yet but i think i should plan ahead.

Design details(in accordance with laterite sand)(IEE std 80-2000)

Total enclosed area-43500

soil resistivity-143.29

RmS value of symetrical fault current-31.5KA

size of conductor -150mm2

duration of fault current for sizing conductor-0.5 sec

surface resistivity-500 ohm metre

spacing between conductor mat-7m

no of concrete test well -4

rod lenght-3m

diameter-2cm

resistance of earth grid (calculated)-0.33 ohms

Can be done but you need to take certain variables in mind. If you like I can help you.

Life2k

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All what i can say : look up www.biddelmeger.com and down load " Getting Down To Earth ".

it is very useful

best regarteds

helal basgo

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which chemical use for reducing the valve

Anything with high conductivity. Like seawater.

Is there any proper method to calculate the earth pit dimensions & electrode dimensions like length and dia