Electrical Earthing

yes u shoud do additionally atleast 10 times stronger then the existing earthing point

Good answer. Yes a new earth (or ground as we use in USA) should be installed. I don't know is "10 time better" is necessary, but depending on usage a 10 to 2 ohm earth resistance should be expected.

I would also install additional earth system for lightning protection and have the 3 earth systems connected together. If building is large enough, I have seen earth rings installed around the perimeter of a building with inspection points to confirm earth resistance and continuity.

normally there is no earthing cable comming from sub station ,

lightning arrestor should be provided with two additional earthing. and

Any distribution board in a building should have minimum two nos. of electrical earthing, one for neutral & the other for the body. Use 50 mm. dia., 2.5 Meter long for Body Earthing and 80 mm. dia., 2.5 Meter long for Neutral Earthing.

from excel earthings- kerala,9446724551

Hello,

Is the cable you are pulling is from secondary of the transformer (of course from secondary of transformer going to distribution system board)? If yes you don't have to put a separate earthing as long as you meet the minimum required ohmic value for earthing required by your local code.

Puting separate earthing to lightning proctection is really dependent of what method of lightning protection you are using. Also, what type of load do your building has?

Regards,

Benn Siman

First of all, please do not confuse earthing with lightning protection, they are two separate systems. Earthing is generally concerned with the internal electrics of a building and requires a reading (acquired from calculations) to be lower than the Earth Fault Loop Impedance allowed by the system itself.

Lightning Protection is generally based on Lightning Strikes per year by the type of buildings, I use Strike Risk by Furse. Protection is based on Type of structure, surrounding buildings, use and area.

Normal earth electrode readings for earthing as per BS 7671 (UK Standard) is 20 ohms for a single electrode however we prefer the lower the better. This still depends on the Earth Fault Loop Impedance which can be provided by the local electricity company.

Lightning Protection reading are generally 10 ohms or lower for the system with each electrode allowed higher values. For example if 4 electrodes then each electrode could be up to 40 ohms as long as the combined resistance is less than 10 ohms in total.

If unsure there are companies that are happy to help with the design for a cost.

yes my friend as i said you in earlier mail, U should provide additional earthing for lightning protection and u can use the existing building earthing system for its domestic use.

The lighting protection should not be mix with the power supply and earthing system of the building.

The lighting protection earthing should be very strong, say 10 time stronger than then the building earthing system (deep and heavy electrodes and calbes with low resistance) and it will be advisable to use copper strips (Bus) inthe place of cables.

It should be consider that When the lightling strike it create mega volts for a short span of time, u should have sufficient grounding and cable thickness to drain it.

Mohammed Ameeruddin

electromechanical engineer.

Linkhill pty ltd, Melbourne, Australia.

The usual lower (1-2 ohms) soil resistivity for electrical circuit and below 10 ohms for Lightning Protection system. This does not mean in physical strength. Since the electrical circuit is more sensitive, the soil must offer very little (1-2 ohms m) resistance for the fault current to disperse in earth mass. This is 10 ohms for Lightning protection charge to be dispersed into the earth mass. This is not physical stronger or weaker aspect. This is about readiness of soil to receive the charge from electrode.

sir,

i read ur bloge sir i am working as a electrical supr. in india please send me ur id because i hv lots of query releted to electrical and it will greatful to if u suggest me for the same.

U have to provide earthing pits additionally.This can be inter connected with the other earthing.

Yes, you need to provide local earthing for electrical and lightning protection earthing for individual bldg. Its international practice.