JustStartingOut
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- Oct 10, 2008
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Hello
Just wondering if anyone can help.
I have been to a house today to change a CU. I completed dead tests and found the following:
-> Ring circuit (originally upstairs ring) has been extended to include the kitchen, it is all wired in red and black 2.5/1.0. Problem is the (r1+r2)/4 is lower for the kitchen circuit than the rest of the ring, and it is less than would be expected from the r1 and r2 values. Is this indicative of interconnection or something else???
-> I disconnected all of the circuits from the CU and found there is continuity (although resistance >99kOhm) between the line of the circuits for downstairs lights and downstairs sockets. Shouldn't these be totally separate? There is also continuity between line and earth on the downstairs light circuit (again resistance >99kOhms) and the Insulation resistance on the downstairs light circuit is 50MegOhm.
On the live test I found
-> TN-S with a Ze of 3.4 ohms. The earth from CU to supply sheath is now <1m long and in 16mm cable. The clamp on the sheath looks like this...
http://www.flickr.com/photos/35250598@N04/3570736419/
Does the clamp need to contact the metal of the sheath, it is just making contact with something black and metallic. Do i need to put in an earth rod and make it TT as this value is too high?
Oh by the way, the main earth was previously a short length of 1mm CSA cable. So don't know if a DIYer has had a bad go at his electrics.
Any thoughts / comments very much appreciated.
Just wondering if anyone can help.
I have been to a house today to change a CU. I completed dead tests and found the following:
-> Ring circuit (originally upstairs ring) has been extended to include the kitchen, it is all wired in red and black 2.5/1.0. Problem is the (r1+r2)/4 is lower for the kitchen circuit than the rest of the ring, and it is less than would be expected from the r1 and r2 values. Is this indicative of interconnection or something else???
-> I disconnected all of the circuits from the CU and found there is continuity (although resistance >99kOhm) between the line of the circuits for downstairs lights and downstairs sockets. Shouldn't these be totally separate? There is also continuity between line and earth on the downstairs light circuit (again resistance >99kOhms) and the Insulation resistance on the downstairs light circuit is 50MegOhm.
On the live test I found
-> TN-S with a Ze of 3.4 ohms. The earth from CU to supply sheath is now <1m long and in 16mm cable. The clamp on the sheath looks like this...
http://www.flickr.com/photos/35250598@N04/3570736419/
Does the clamp need to contact the metal of the sheath, it is just making contact with something black and metallic. Do i need to put in an earth rod and make it TT as this value is too high?
Oh by the way, the main earth was previously a short length of 1mm CSA cable. So don't know if a DIYer has had a bad go at his electrics.
Any thoughts / comments very much appreciated.