Earthing-touch & step voltage

Do you belong to Electrical Engineering? If yes...study relevant books/docs. If No, its of no use for you.

Hello Guest,

Are you building a:

1. Power station

2. Substation

3. TV transmitter station

4. Radio Transmitter station

5. DC Transmision link - Sending

6. DC Transmision link - Receiving

Advise voltages of the installation, and whether AC or DC.

Advise expected Earth currents through the electrode/s.

Advise the ground area of the installation.

Advise type of 'soil':

1. Swamp bottom
2. Seawater surrounding peninsula
3. heavy clay
4. Shingle (gravel fill)
5. Garden loam/silt
   
6. granite outcrop
7. Desert sand
   
8. Other, specify please
   

There are further specifics needed, but the above should do as a starting point.

Looking forward to your reply, with thank you.

Kind Regards....

thanks for reply

it will be a 33kv sub station 9mva

soil is desert sand

I do not care to repeat Sparky's questions, which are to the point.

I am not even willing to believe that the soil resistance is known, as it is seasonally dependent to say the least. And I bet, that nobody knows, what it will show after an 8 weeks of drought.

If it is a safety ground, you may have to go down to the ground water table level, and do something elaborate to maintain year around. Bonding it back to the main power panel is still absolutely needed.

If it is a sensor ground, it is a customary and idiotic specification, as modern sensors come in not grounded and isolated flavors. It is idiotic and selfdefeating, as soon as a power ground is installed nearby.

If it is Radio Frequency ground, a ground mat, not the DC value is the deciding factor.

You know why earth electrode is used in Earth Mat design? To get advantage over non uniform soil resistivity of earth layers. In software the 2-or 3 layer model can be created to get better calculation of earth resistance. Hence drought will nit affect if we use more and deeper electrode. In a project in middle east where soil resistivity if tremendously high, engineers used a wells quite deeper and inserted fe nos of electrode in few places. Alternatively a treated layer of soil can be used on earth and earth mat can be used. This concept is being used in many projects.