single earth

[oldtimer]

Looked at a CU change today and it was pretty straight forward I tested Ze at 0.08 ohms the pfc was 5kA but the lights have been wired in an existing conduit with 2 circits but 1 earth all 1.5mm. I was thinking of putting in an metal CU so I could connect the conduit into the board. Also both light circuits have been moved to one fuse to make room for an electric shower. Also did an IR and got 35meg

So the question is were do I stand with the single earth ?

I served my time on the 14th yes the 14th edition and my understanding was as long as the conduit is "electrically and mechanically sound".

 

[lamb]

You can terminate the existing conduits into steel trunking, then slot the trunking and use grommet strip where it meets the C/U, then you can use an insulated C/U.

 

[oldtimer]

Yep good shout but forgot to add that as the unit is fitted into a cupboard I am limited to 250mm in hight so as the conduit is fixed then I ned to get a metal board.

thank anyway

 

[nickblake]

PFC 5k were you sat on the sub station , one of the problems you could find with the doubled up circuit is shared neutrals if your upgrading your board i assume your installing a 17th edition board with RCD as for the earth use it as it is but lable the board and mark on the certificate, you can use the conduit as an earth or if you could install a new earth to

 

[oldtimer]

Yes I am using a wylex metal version of the standard 17th edition plastic unit only problem is that it is £50 more but hey ho as for the lights I checked a couple of switches and the earth is looped through the problem as I said was there is 2 light circuits in the conduit but one earth

 

[sparkylad]

a cpc can protect more than one circuit providing its csa is adequate for the largest of circuit cables. also bear in mind if a seperate cpc is run in and not mechanically protected throughout then min. size is 4mm.

 

[oldtimer]

After all that customer contacted me and thought I was a bit expensive

Well I said due to set up I have to use a metal version of the DB and the extra cost is £70 and then I have to earth the water and gas as there is no existing plus upgrade main earth and fit an MET customer also want an EIC for the whole installation.

Well i said thats the best I can do so if you get anybody cheaper take it doesnt mean you will get the same standard but its a free world after all.

One thing I did during the survey I tested PFC Ze plus cookerand socket Zs and an IR wrote the results down and he asked for a copy any takers on my reply