Have you considered the load considerations further back to best align your protection standards as the change of TX will require upscale protection changes, is this part of a radial or ring distribution network, there are many things to consider if you cannot perform a like for like change.
Most Substations these days use the rolling sphere method for the erection of lightening spires with a direct connection to ground from the base of the spire, the rolling sphere principle uses the pattern of where the lightening strikes have the most engery with an intersecting area of...
