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> You need to specify to install a grounding rod, as well as the length Umm. When electrician installed grounding rod for me, he did measurements. He couldn't
by jve 4y ago
> You need to specify to install a grounding rod, as well as the length
Umm. When electrician installed grounding rod for me, he did measurements. He couldn't tell how much grounding rods will I need. Because some get lucky and get tapped into undeground water and immediately gets low resistance.
In my case, we couldn't use a single spot as the rods were too hard to go in for required length, so 4 places actually were used and connected together while appropriate resistance was achieved.
Moreover, I don't much about it but someone may approve/reject the following I heard from another electrician: If your ground provides VERY LOW resistance, then it is also bad, because it can work backwards, providing a path from outside to your house.
- tuatoru 4y ago> some get lucky and get tapped into undeground water and immediately gets low resistance. You need to be careful about this. In many places the depth of the water table varies a lot depending on the season of the year. Generally it sounds like your electrician was correctly following a well designed code of practice. Regarding what the other electrician said, for current to flow there needs to be a potential difference and a circuit. In this case your house (roof, frame, etc) is very well connected to the ground it sits on. If it's a long way from your house to the transformer, with exposed overhead power lines, there could be a potential difference with those. This is where the "level 2" (building entry point) protection mentioned by another commenter comes in. It used to involve fuse(s), heavy duty spark gap(s) and heavy duty varistor(s). I don't know about these days, but I wouldn't trust anything with active control to continue to protect after a lighting strike. Or during it.