The system in our house at the moment lacks any earth bonding for the water and gas mains. Aiming to rectify this soon.
We have a TT system. I know that a minimum 6mm^2 earth conductor is specified, but I was wondering under what conditions I might want to specify larger.
The water main is near (say a 5m cable run I guess) the gas main is a longer and much more awkward run at least 20 M.
If there is any chance your supply could be changed then it would be prudent to use 10mm^2.
Adam
In message , ARWadsworth writes
Good point. We have no plans to change the supply, but new supplies seem to be underground cable as opposed to overhead. And one never knows what will happen in the future.
The gas one will be a faff as it comes into the cellar a long way from the CU, and will require lifting floorboards in the hall way and going through a couple of walls to get to the CU, so wouldn't wanting to be redoing that if I can avoid it.
Do the runs need to go back to the CU directly, or can I daisy chain them? As it will run past the incoming water main
You can do the bonding with one continuous run. The cable must not be jointed at the earth clamp where you bond the water. You would have to remove the insulation from the earth cable at that point and clamp it without cutting the copper.
For a 5 meter run of cable for the water I would not consider daisy chaining. There is something in either the NICEIC or IET guides (that I cannot find ATM) that says daisy chaining is not best practice.
Adam
Star connection back to earth point is better practice. daisy chain is always risk a break anywhere affects all upstream.
In message , Rick Hughes writes
Direct runs in 10mm^2 it is
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