Earth rod, RCD tripping fault

[Jel]

1st question:
Had to install a earth Rod in rural area today because the Ze on the current TN-S system was too high.
All the circuits are brand new, but for some reason a circuit with LED Haler downslight on seem to trip when the systems earth is changed to the earth rod. The Ze of the system is 11.1ohms.
Every other circuit is fine.

2nd Question:
As my Ze is higher, all the readings im getting for my Zs are too high, but would i be right in thinking they circuits meet the disconnection times because of the RCD, so the high Zs does not matter?

 

[GLENNSPARK]

whats the type and rating of the overcurrent device feeding the supply to the outbuilding.....

 

[tony mc]

If thast the Zdb at the out building Guitarist has already asked the question.

Makes a bit more sense then.
I'm assuming you have the correct sized cable for the load/length running to the outbuilding?

 

[Jel]

Yes it is the correct cables size. 25mm 3 core SWA, only 10 metres.
The building has very small load, half the size of normal house.

 

[Jel]

whats the type and rating of the overcurrent device feeding the supply to the outbuilding.....

80amp 1361 Type 2

 

[GLENNSPARK]

well acording to the osg...for 10 and 16 mm csa protective conductor size...your max Zs for a BS 1361 80A is 0.40 ohms....

 

[GLENNSPARK]

sorry guys...its late ...of course its TT RCD n all that...

 

[Engineer54]

My heads sort of spinning here!!! What have you connected the SWA (earthing) of this cable too, at the origin in the house and how have you connected it?? I take it you have glanded both ends??

I really don't know why you have rodded this out building, if the DNO provided earthing point is not functioning at a suitable protection level, they are duty bound to maintain it, even if it means PME'ing the supply if it's available...

Your earth rod(s) will come in handy then, as a locally installed part of the multiple earthing arrangement!! lol!!!

 

[Jel]

I will contact DNO and ask them to come down. I have never installed earth rod before, do thought I might aswell get some experience rather than call DNO.

 

[Guitarist]

With the greatest respect, trying to get experience by playing with an earthing system is not the best idea. Better to get professional help here.
Also, 25mm swa for an outbuilding is probably excessive...

 

[tony mc]

Did we ever find out the ZE of the main premises that the SWA was connected too?

As the 1.48 ohms is at the outbuilding so its not ZE !!!

 

[GLENNSPARK]

My heads sort of spinning here!!! What have you connected the SWA (earthing) of this cable too, at the origin in the house and how have you connected it?? I take it you have glanded both ends??

I really don't know why you have rodded this out building, if the DNO provided earthing point is not functioning at a suitable protection level, they are duty bound to maintain it, even if it means PME'ing the supply if it's available...

Your earth rod(s) will come in handy then, as a locally installed part of the multiple earthing arrangement!! lol!!!

well this is what i was getting at a bit earlier in this thread eng......DNOs dodgin out of their responsibilities again.....keeps surfacing this one doesn`t it?!!....

 

[GLENNSPARK]

Did we ever find out the ZE of the main premises that the SWA was connected too?

As the 1.48 ohms is at the outbuilding so its not ZE !!!

yep...this is why i refered to Zdb earlier....

 

[GLENNSPARK]

the thing is n all Tony mc with these threads....never enough info from the O/Ps.....thats when you start to get the fealin that your goin round n round...lol...

 

[tony mc]

Glad Im not the only one a little confused!

 

[GLENNSPARK]

thing is tony mc is i was tired yesterday eveinig and i was just starting to put down nosense.....thats when its time to go...lol.....