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So anything under 200 meg is perfectly fine for Ra?If it is a client owned TT, anything over 200 Mohms is unstable.
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Discuss Max ze values in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
So anything under 200 meg is perfectly fine for Ra?If it is a client owned TT, anything over 200 Mohms is unstable.
So anything under 200 meg is perfectly fine for Ra?
Any excuse to take the mick and I'm gonna take it mate. Sorry200ohms, my mistake. Should pay better attention to what I am typing.
but since then ive connected generators which have needed readings of 200-250 ohms to be correct for the rcd used ,
Only one ohm out. 20Ω for a LV nest at >8m from the MV nest. <8M then <1Ω max and they can be linked.
It’s the difference between a “hot” and “cold” site.
We do not guarantee any "data" for external earth loop impedance. the expected max for PME
networks in the UKPN area for single phase in 0.38. For cable sheath it is much higher, normally
up to 1 ohm. The 21 mentioned is the figure with no earth provided.
It could be much higher in any of the above examples.
We do not guarantee any "data" for external earth loop impedance. the expected max for PME
networks in the UKPN area for single phase in 0.38. For cable sheath it is much higher, normally
up to 1 ohm. The 21 mentioned is the figure with no earth provided.
It could be much higher in any of the above examples.
It always used to be 21 ohms!! lol!!
To be honest, we have always achieved sub 1 ohm on our earthing systems and have generally linked MV-LV earthing via a removable link bus bar arrangements. An 8 metre separation can at times be almost impossible, to achieve, especially when trying to also comply with other related factors...
I was told by niceic inspector to input this 21 ohm figure for earthing arrangement Ze for TT systems for the DNO earth instead of the 200 ohm i used to input into that box to cover your installation ZE.
Slightly confusing in the sense you're supplying your own earth, which must meet the 200 ohm (obviously you want it as low as possible) criteria and you have no control over the DNO supply earth which doesnt even enter the property. Doesn't make 100% sense to me but I'll follow orders and do as I'm told
I was told by niceic inspector to input this 21 ohm figure for earthing arrangement Ze for TT systems for the DNO earth instead of the 200 ohm i used to input into that box to cover your installation ZE.
Slightly confusing in the sense you're supplying your own earth, which must meet the 200 ohm (obviously you want it as low as possible) criteria and you have no control over the DNO supply earth which doesnt even enter the property. Doesn't make 100% sense to me but I'll follow orders and do as I'm told
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