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Due to high resistivity value I am not able to reduce the grid resistance. Although my touch and step potentials are within limits still GPR value is higher than specified value of 5kV. I need to convince my client that GPR of 7.8 kV is a safe value. I have tried arguing on the point that as...

Hi, I have following questions for cable sizing laid in ductbanks: Whether to consider soil temperature or ambient air temperature while calculation of cable ampacities in ductbanks? Further how to consider small air gap in ducts carrying cables ? Thanks.

Yes it is earthed.

Dear Skogsgurra Can you suggest some reading material on this topic ? Thanks.

Its a D/Y Trafo

Hi, I want to know the implications of connecting unbalanced delta load to secondary (Star Winding) of transformer. Thanks.

Hi Fellows, We are currently using CDEGS software package for grounding system design an analysis. From one of IEEE surveys I found that WinIGS is also very popular these days but I am unable to get my hands on the demo version of the same for evaluation purpose. It would be nice if some one...

If all the equipment, metallic objects and cable shields are properly bonded and connected to the main earthing mesh and the air termination system is designed properly. Then, is there a requirement for SPD (surge protection device) in the control building? If yes, then kindly give some...

Yep I know that and that is the main problem that even after backfill the values will not be very accurate and because of this the system will be over designed. Normally it is not a big problem to over design but you see cost cuts are desired in recession. Thanks.

The site is excavated till a level of 10 meter, so don’t you think that a two layer soil model be used instead of three layer one. Thanks.

Normally as most earthing design practitioners take the resistivity values before excavating for the earthing mash. But in our case the site is already excavated for the said purpose and the resistivity data is available further bellow that level. So can any one recommend a technique which we...

Thanks a lot CarlB. It was very helpful. Thanks.

Dear escrowe. I have taken the civil boring data from project managment and I am only concerned for 1.2m depth. As you have mentioned that it is possible to have an estimate by having information of grain size and moisture content, so can you refer to some reference material? Thanks. CarlB...

Is there any methodology by which one can calculate ground temperature from air/ambient temperature? I want to calculate de-rating factors for cable current carrying capacity but the project specifications don’t give any information about ground temperature.