Are 2 Earth Rods Needed ?

[TPES]

TT Supply.

Main CU, With earth to rod outside.

Second CU for storage heaters, Also on a seperate Rod outside.

I have been told this second rod is not needed for the second board, Aslong as the resistance of the first earth on the 1st CU is within the reg limits (lower than 200 Ohms) then the first rod can also earth the second CU. Is this correct?

Ive measured the first main Rod to be 123 Ohms, I know its unusually high but its within the limits..

What do you lot think?

 

[TUX]

1 rod is fine link ed to both boards and 123 ohms is afine for tt system 200 ohms is only a recomendation and higher resistances are still acceptable

regards tux

 

[Spudnik]

.... 123 ohms is afine for tt system 200 ohms is only a recomendation and higher resistances are still acceptable

regards tux

Indeed it is only a recommendation, however it is said that anything over 200ohms could be unstable.

 

[Mr Mark Sparks]

i agree
the nic give a guide of 100 ohms but 200 is fine so your reading is pretty good really
i woulld say 1 stake per main incomer
so your stake to earth bar then to each cu from there

 

[andyb]

All the above are correct.
All you need is an earth and a main earth terminal which both boards can use.
However , there is nothing wrong in using 2 rods linked to give you a lower earth reading.

 

[acat]

Perfectly ok with one rod, perfectly ok with two why fix it if its not broken


Chris