Substation Ground Grids

Is your client a power company? Using insulated conductors in the ground is counter to what the grid is for! Using insulated conductors connected to the uninsulated grid protects the above-ground conductor from the elements.

I'd check with the client or the engineer who more than likely mis-specified insulated ground grid.

Highly unusual request.

I have seen many power plants and hundreds of substations but never insulated conductors.

You need to be careful in the type of copper you use.

Our standard is for compact copper

The purpose of a ground grid is to get as much contact as possible between the grid (copper conductor) and earth as possible to achive a low earth-ground resistance. Having an insulated condutor completely defeats this purpose.

actually insulated grids are used sometimes. you need to know the soil. if there is high levels of chlorides and/or sulfates, low resistivity, etc, then the copper grid can actually corrode quickly... frequent ground rods are used with an insulated grid.