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High Impedance On Domestic Tt System
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<blockquote data-quote="Jammin" data-source="post: 391155"><p>Hi folks,</p><p></p><p>Tested the earth electrode on a TT system the other day and got a reading of 323 ohms. Normally I would install additional spikes to bring the value down, however the property is completely surrounded by concrete, and the customer will not consent to me digging anything up. so I removed the existing spike and installed a bigger one and got a reading of 282 ohms.</p><p></p><p>The spike I pulled out was in good condition but very dry as it appears not much moisture is penetrating the concrete. I can see no way of getting the reading below 200 with the restrictions the customer has implemented. I thought one possibility would be to get him to ask the DNO to upgrade him to a TNCS which would probably cost him, so he won't go for that!</p><p></p><p>Would I be right in thinking as the whole installation is protected by a 30ma RCD that because Ra divided by 0.03 allows for 1666 ohms for disconnection to occur it could be left as is. or do I walk away from it? </p></blockquote><p></p>
[QUOTE="Jammin, post: 391155"] Hi folks, Tested the earth electrode on a TT system the other day and got a reading of 323 ohms. Normally I would install additional spikes to bring the value down, however the property is completely surrounded by concrete, and the customer will not consent to me digging anything up. so I removed the existing spike and installed a bigger one and got a reading of 282 ohms. The spike I pulled out was in good condition but very dry as it appears not much moisture is penetrating the concrete. I can see no way of getting the reading below 200 with the restrictions the customer has implemented. I thought one possibility would be to get him to ask the DNO to upgrade him to a TNCS which would probably cost him, so he won't go for that! Would I be right in thinking as the whole installation is protected by a 30ma RCD that because Ra divided by 0.03 allows for 1666 ohms for disconnection to occur it could be left as is. or do I walk away from it? [/QUOTE]
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