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Earthing question

Discussion in 'Electrics UK' started by skymatt, 16 May 2005.

This topic originated from the How to page called Choosing the correct size cable.

  1. skymatt

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    I am currently at the tail end of moderising my house. I have now realised that the light switches / hanging lights are all metal but have no proper earthing.

    I do not really want to replace all the lighting rings as the house is in a near finished. I have worked out that I could run earthing cable for all the light switches and 75% of the lighting roses (The rest I could replace with plastic roses) via some chasing of the walls and lifting the floor boards back to the consumer unit. Which would minimise the mess

    Is this a viable option?
     
  2. delmel

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    not modernised then. If a jobs got to be done its worth doing correctly. I hear you say that will be ok, and yes it will utill you are unfortunate enough to have a fault condition introduced.
     
  3. skymatt

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    What exactly due you mean by a fault condition introduced?
     
  4. Big_Spark

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    Skymat, replacing accessories with plastic does not remove the need for the cable to incorporate an Earth.

    The whole lighting circuit, and probably the Ring main needs to be rewired. This may not be what you wanted to hear, but this is the situation you are faced with.

    The cpc (Earth) in a cable has two roles.

    1: It protects the users of an installation from dangerous currents under fault conditions and removes them to ground, causing protective devices to operate thus disconnecting the supply.

    2: It protects the cables from external influences that would otherwise go undetected and could lead to a fatal shock or fire as no earth path means that no automatic disconnection of the supply can occur.

    With respect, if you do not understand the real need for cables to incorporate a cpc, then you should not do this work yourself and should at least consider calling in a professional.
     
  5. skymatt

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    FWL_Engineer

    I hear what you are saying. The ring main is in good order and I have had that checked out as a new CU was installed.

    With the lighting circuits if I ran earthing cable to 100% of the roses and switches would this be okay? And I except this would not be as good as a re wire but would it still do the job?
     
  6. keyplayer

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    How is this easier than a rewire??
     
  7. kendor

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    you could stick an isolation transformer on every lighting outlet.

    No only kidding. ;)
     
  8. Damocles

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    As everyone posting here knows, lots of houses still have a missing earth in the lighting circuit. Nowadays it is quite common to buy electrical equipment which is 'double insulated'. In other words, designed to work without an earth and supplied with a mains cable having only two cores. I mention this to demonstrate that an earth is not always essential.

    So it rather depends whether your lighting accessories are also designed to work without an earth.

    Current regulations specify an earth on lighting circuits. they also specify lots of other things which are likely to be missing from your house and many other houses. Even some rewired in the last few years. Regulations change all the time. It does not mean that everything has to be ripped out and replaced each time they are revised. Which would probably be every year.
     
  9. ban-all-sheds

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    In the light (sorry) of what you did not do with the electrical system, would you care to rephrase that?
     
  10. skymatt

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    I have seen the light :idea: ( Bad joke I know) I have spent a year doing all the work and just was not expecting the lighting issue. I now plan to spend this weekend re wiring the lighting circuits with two mates who are electricans. (Paying for there time in beer).
    Yet another lesson learnt if I am every mad enougth to do up another house :rolleyes:
     
  11. Big_Spark

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    Skymatt, good decision there and nice to see that someone does listen to advice when given by several people.

    Good luck over the weekend, at leats when this is complete there will be "light at the end of the tunnel" for the refurb of the house. (Sorry, just thought I would get in on the bad puns :D)
     
  12. bpowell555

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    Handy couple of mates!

    :cool:
     
  13. skymatt

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    All done. A very hard weekends work and some finishing plastering to be done. But now much happier :LOL: that the lighting rings are all new and earthed. I even have a light in my loft!
     
  14. kevplumb

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    wot no bad head :?: :?: :?: ;)
     

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