Msii

From reading all the comments I think there isn't the perfect solution. I would say move the earth from that particular area to another. increase the earth wire size or both with the earth rod/spike. A cheat would be getting a lesser sensitive earth linkage with a higher rating. Here is an advantage or installing 2 spike or a larger spike = conductivity will be hire thus carrying more current than letting go. changing area = conductivity of an area may vary sometimes. installing earth linkage before the main, on the earth which is just stretching electrical fundamentals will trip the earth and not the main power. in this case make sure your db has another source of earthing to help in a case where the linkage is disconnected.