Okay, trying to get my head round this
Commercial site (farm converted to shops, supply still from main farmhouse)
100amp 3 phase TNCS supply
Issues started 3 weeks ago, cutout fuses blowing, replaced by DNO twice and then last week again, however this time arcing was observed from the main distribution board, and on inspection the busbar section of the board was visibly charred/melted. Distribution board is only 7 years old, Hager invicta 3.
All isolated overnight and then all sub boards connected to a generator the next day to restore supplies, so submains were physically disconnected from the house to allow the repair works to take place.
Today, finished fitting the distribution board prior to testing and reconnecting the submains. The board has a direct connection to a local rod, but also to the cutout. When I went to join the DNO earth to the board, there was a lot of sparking. Disconnected any other earths to check it wasn’t current from anywhere in the Installation and basically current was flowing from between the dno neutral/earth.
DNO attended, didn’t even come in and look, when I described the issue, he just said ‘join them together, it’ll be fine’ I’m not too happy with that. As i see it, a fault on their network is using this earth rod as a return path.
Not too sure what to do next, other than to get the DNO out again and hope someone more helpful turns up. I’m not comfortable with the idea of leaving it like this and also my customer is now saying he thinks that this caused the other issues! (I’m not in agreement necessarily with that one)
Commercial site (farm converted to shops, supply still from main farmhouse)
100amp 3 phase TNCS supply
Issues started 3 weeks ago, cutout fuses blowing, replaced by DNO twice and then last week again, however this time arcing was observed from the main distribution board, and on inspection the busbar section of the board was visibly charred/melted. Distribution board is only 7 years old, Hager invicta 3.
All isolated overnight and then all sub boards connected to a generator the next day to restore supplies, so submains were physically disconnected from the house to allow the repair works to take place.
Today, finished fitting the distribution board prior to testing and reconnecting the submains. The board has a direct connection to a local rod, but also to the cutout. When I went to join the DNO earth to the board, there was a lot of sparking. Disconnected any other earths to check it wasn’t current from anywhere in the Installation and basically current was flowing from between the dno neutral/earth.
DNO attended, didn’t even come in and look, when I described the issue, he just said ‘join them together, it’ll be fine’ I’m not too happy with that. As i see it, a fault on their network is using this earth rod as a return path.
Not too sure what to do next, other than to get the DNO out again and hope someone more helpful turns up. I’m not comfortable with the idea of leaving it like this and also my customer is now saying he thinks that this caused the other issues! (I’m not in agreement necessarily with that one)