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Discuss How Far Out From House To Locate Earth Rod? in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. happyhippydad
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    happyhippydad Member Electrician's Arms

    Location:
    Gloucestershire
    A few days ago I went to a house which had no main earth and no main bonding.

    I have now installed the bonding and also an earth rod and managed to get a satisfactory Ra. I did have a couple of failed attempts at getting the earth rod in as I just hit rock (or at least something very hard) and it was a right pain to get the rod out again to relocate.

    I have a few questions..

    1. Is there generally builders rubble close to the house underground? If so how far out do you generally locate the rod from the side of the house?
    2. Any tips for getting that rod through anything hard? I drilled down a bit (400mm) but there were still hard objects in the places that I failed to locate the rod in initially.

    Cheers.
     
  2. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    generally about 3 ft. to clear the builder's rubble. a good sds drill on hammer only with a modified socket to hammer the rod/s in. if you hit rock, it's a case of trying eleswhere, or if no depth available, install a mesh grid.
     
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  3. happyhippydad
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    happyhippydad Member Electrician's Arms

    Location:
    Gloucestershire
    What happens if you're already 3 or 4ft down? Can you get the rod back out? I had ridiculous hassle getting it back out at about 1-2ft!
     
  4. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    leave it in and couple it to the next one that goes deeper.
     
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  5. happyhippydad
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    happyhippydad Member Electrician's Arms

    Location:
    Gloucestershire
    Thanks Tel.
     
  6. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    but try and miss the incoming gas, water and leccy.
     
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  7. Flanders
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    Flanders Regular EF Member

    Location:
    Tamworth
    And the drainage and soil pipes
     
  8. happyhippydad
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    happyhippydad Member Electrician's Arms

    Location:
    Gloucestershire
    Just as a matter of interest (and a bit of fun :)) has anyone hit one before? I had a good look around to try and imagine where the gas/water/waste pipes would be, but it's impossible to know for sure!
     
  9. Richard Burns
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    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    I generally find that if there is say a layer of concrete 2 ft down then if you drill down with a 1 m drill bit that is a bit smaller than the rod (or the same size if really bad) then the rod will be able to be pushed through. Most building stuff is gone once you are below 3 ft deep.
    If it is just that the earth has a lot of rocks in it then you will still get stuck.
    If you are using an SDS and have got stuck then sometimes changing the SDS to rotate rather than hammer can free up a rod (don't break your wrist), but it is not very easy in general to remove a rod without digging it out, especially if it is jammed on rocks.
     
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  10. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    Never had to put an earth rod in, but sort of knowing the soil and rain water pipe runs in my garden, I wouldn't want install a rod anyway but close to the house. I suppose it's not too much of an issue in properties out in the sticks (where most TT's are gonna be), but anywhere else, I'd be too nervous of hitting a pipe. Seen vids on guys using ground pipe detectors, before installing a rod and I'm told you can approach the local council for pipe runs etc?
     
  11. happyhippydad
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    happyhippydad Member Electrician's Arms

    Location:
    Gloucestershire
    Thanks for that Richard, some useful advice.
     
  12. spinlondon
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    spinlondon Trusted Advisor

    Location:
    Harlow Essex
    Rods should be as close as possible to the house.
     
  13. Richard Burns
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    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    Can you expand more on why you have stated this and the advantages it may have?
    This runs counter to my understanding of maintaining ground quality and soil dampness for a rod.
     
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  14. happyhippydad
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    happyhippydad Member Electrician's Arms

    Location:
    Gloucestershire
    Perhaps SL is thinking of the length of the cable run which would add to the resistance or perhaps increasing the chance of damage by locating at a distance away from the house. However, this is just a guess and both of these reasons I would not feel to be more important than the level of soil resistivity which may be pretty poor right next to the house.

    Just as a bit extra, i'd be interested in getting an honest picture of what size rods people genuinely fit in a domestic situation? I realise the 3/8" 4ft rod gets called a twig, but it is a very common size seen in domestic properties ( I very rarely see a 5/8") and whenever I have used one I have obtained an Ra < 200ohms.
     
    Last edited: Aug 28, 2016
  15. Richard Burns
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    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    Remember that the length of cable will make no appreciable difference to the overall resistance compared to the resistance of the rod itself. changing the cable resistance from 0.01 ohm to 0.5 ohms is immaterial if the rod has a resistance of 20 ohms.
     
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  16. Knobhead
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    Knobhead Guest

    Why?
     
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  17. ruston
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    ruston Trusted Advisor

    Location:
    Northumberland
    If you can get down two of these close to the house there is usually nothing below that, as any service will usually rise to enter the house. Within reason services will come in in straight lines.
    Save yourself worry and dig a cross trench if it is possible.
    If you get down to clay and there is no 'mix' ( mixed excavated materials) in it ; it is usually an indication of undisturbed ground.

    shopping.jpg
     
  18. Midwest
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    Midwest Electrician's Arms

    Location:
    Oxfordshire
    Perhaps he's concerned the same as I would be on puncturing another service. :)
     
  19. Knobhead
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    Knobhead Guest

    I still want to know why the rods should be close to the house.


    The wider the spread of the rods the more stable and efficient the earth nest. Rods as in plural.
     
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  20. Leesparkykent
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    Leesparkykent You Rock Gmes Staff Member Trusted Advisor

    Location:
    Kent
    I would be interested to know as well...
     
  21. ruston
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    ruston Trusted Advisor

    Location:
    Northumberland
    Usually because there is no choice , up here many of the terraced house (ex NCB ) have no , or very small gardens. Some the back and front doors are stepped straight onto the pavement.
    In an perfect situation Tony's post is ideal.
    My post was mainly aimed at finding the services where worry about damage knocking rods in ,as asked in an earlier post.
     
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