earth loop impedance

5 Mar 2008
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United Kingdom
I have a rural house with a Zs of 90ohms. How do I get this down to an acceptable level. The house has a Ze of 280 ohms with two earth rods in the ground. The supply to the house has been checked and has no faults.
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Confused by this as Ze = Zs + (R1&R2) so your figures cannot add up. Please check and re-post so we can help.
Ze = Zs + (R1&R2)

Zs = Ze + (R1&R2)

Zs can be lower than Ze on a TT system if both quantities are measured
as Ze is measured with main equi potential bonding disconnected Zs will be measured with it connected and there could be a good earth on water supply.
The Ze for a TT for reliability should not exceed 200 ohms. This can be brought down a bit by adding more rods (need to be adequately spaced), a longer rod or using an additive in the ground. With a TT system as the general mass of earth is being used for the return path you will struggle to get the figure down to anywhere near a TN system hence the reason RCDs are required to used to provide protection against indirect contact.
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What was I saying!! :oops: :oops: Never trust your brain after a nightshift. Thanks for pointing out my own stupidity!!
thankyou for your advice.
I do have rcd protected circuits but would still prefer to have lower eli readings.

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