Jerry asks this question, which concerns a new house and possible deviations from Wiring Regulations. It has been answered by the NICEIC (Theme – Distribution Equipment including Cable Management):
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Question: Having just moved into a new build house, I decided to add an outdoor socket. Taking a socket front off, I found a twin and earth cable made off but not connected. My first thought was that the cable had broken and needed to be reconnected, but all sockets worked.
Then I thought it must be an additional cable put in by the sparkies for any extras. I was always taught to leave the cable uncut and taped off, so what is the correct procedure for this type of additional cable?
Also, from further investigation, no socket back boxes are earthed, but the light switch back boxes are.
Furthermore, there is no earth cable to the metal plate light switches. I was always taught to earth these - is this OK now under the latest regulations, as everything is supplied via an RCD?
I also believed that I should have been given a copy of the test results in the distribution board, but was given a Part P certificate and was told that I don't need a copy as the builders have it. Are my standards too high and my understanding of the regulations incorrect?
Answer: It is always good practice to terminate unused cables and any spare unused cores of cables. You do not state whether this cable was energised but this clearly demonstrates the need to isolate circuits before working on them.
Metal back boxes are considered to be exposed conductive parts and therefore require to be earthed. However, if the back box has a ‘fixed’ lug, then this is considered to provide a good connection.
If both lugs were adjustable, then a ‘fly ‘lead would be required to earth the back box. It is down to the designer of the installation to decide whether the reliability of the connection can be assured for the lifetime of the installation.
For further guidance on earthing of accessories and terminations refer to NICEIC / ELECSA ‘Snags and Solutions’ Earthing and Bonding.
As this is a new installation, the certificate would have been issued to the person who ordered the work (the builder). However it seems reasonable that he should provide you a copy of the certificate as the new owner of the property.
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