Discuss Metal lamppost in garden... TNC-S in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. weevilward
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    weevilward EF Member

    Location:
    United Kingdom
    Evening all,
    Need some opinions on this one please:
    TNC-S house, complete new install, all going to plan, nearly finished second fix, customer then arrives with a huge metal lamppost (bought from Frinton-on-sea promenade...) and wants it hooked up in the back garden.
    What is the general consensus on this - my concern is: in the event of loss is supply neutral, everything connected to MET, including that lamppost, will rise to a voltage, anyone touches it may get a shock?
    Or, will the fact it's planted in the earth keep any possible voltage down?
    Am I making something out of nothing here or would this be safer as a TT?

    Any thoughts welcome.
     
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  2. westward10
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    westward10 Sponsored by failure. Electrician's Arms

    Location:
    Northamptonshire
    What is it with this neutral loss, in the house no one bothers but go outside and there are shouts of ROD IT.
     
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    Last edited: May 19, 2017
  3. weevilward
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    weevilward EF Member

    Location:
    United Kingdom
    Ok, so touching a radiator bonded in the house in no different to touching a lamppost bonded in the garden? Is that what you're getting at?
     
  4. weevilward
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    weevilward EF Member

    Location:
    United Kingdom
    Ok, so touching a radiator bonded in the house in no different to touching a lamppost bonded in the garden? Is that what you're getting at?
     
  5. Flanders
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    Flanders Regular EF Member

    Location:
    Tamworth
    Im think there is somthing in special location for lamp post but it may be relating to street furniture
     
  6. Leesparkykent
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    Leesparkykent You Rock Gmes Staff Member Trusted Advisor

    Location:
    Kent
    The post will propably act as one big rod.
     
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  7. westward10
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    westward10 Sponsored by failure. Electrician's Arms

    Location:
    Northamptonshire
    Most lighting columns on the highway are PME they seem okay.
     
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  8. weevilward
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    weevilward EF Member

    Location:
    United Kingdom
    So I'm reading too much into it.
    Thanks fellas. Never thought twice about domestic outside lighting before, but when something different comes along it makes you think twice...
     
  9. Richard Burns
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    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    This is probably a case of minimal risk. In general you are not constantly handling a lamppost, as opposed to hand held electrical equipment, and so the risk of neutral loss fault occurring and it being a risk due to contact are low.
    Bonding will have limited effect since the potential you are trying to eliminate is between earth and the supply and bonding will only limit the PD between the MET and the supply.
    Within a property there should be no potential differences because the bonding connects all sources of potential difference together. Outside a property without installing conductive mats in the ground you cannot avoid being in the presence of a nominal 0V from true earth and so the risk is increased.
     
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  10. Paul mccullagh
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    Paul mccullagh EF Member

    Location:
    Cambridgeshire
    Run swa to the lamp post (volt drop calculations) bonded on a 30MA rcd in the consumer unit job done!
     
  11. westward10
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    westward10 Sponsored by failure. Electrician's Arms

    Location:
    Northamptonshire
    Why would it require rcd protection.
     
  12. westward10
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    westward10 Sponsored by failure. Electrician's Arms

    Location:
    Northamptonshire
    This was suggested many years ago by the ILE but was felt the column would be unreliable as an electrode due to corrosion, protection on the column to prevent corrosion and the means of bedding it in the ground.
     
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  13. weevilward
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    weevilward EF Member

    Location:
    United Kingdom
    It doesn't need RCD but it wouldn't hurt to have it.
    Yeah this one is pretty rusty!
     
  14. weevilward
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    weevilward EF Member

    Location:
    United Kingdom
    Thanks Richard, this makes sense.
     
  15. Paul mccullagh
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    Paul mccullagh EF Member

    Location:
    Cambridgeshire
    I would personally protect this with a rcd due to someone dismantling fixtures and changing a light bulb!
     
  16. wirepuller
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    wirepuller Trusted Advisor

    Location:
    south uk
    Well you cud'a knocked me down with a feather when I saw this, normally it's only sheds that bring people out in a cold sweat when TNCS is mentioned. I think I've pointed out before that those who come over all unnecessary at the mention of a shed never seem to get that queasy feeling with other outdoor installs.
    So good on'yer Weevilward, shows you are thinking about what you are doing rather than just following the herd and subscribing to myths.
     
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  17. static zap
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    static zap Regular EF Member

    Location:
    west midlands
    Is it the tallest piece of garden furniture , on a Hill Top !
    (that's the other kind of rod ! )
     
  18. weevilward
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    weevilward EF Member

    Location:
    United Kingdom
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  19. stevethesparks
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    stevethesparks Electrician's Arms

    Location:
    Northampton
    How many people think to make their outdoor socket TT, whats the difference?
     
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  20. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    If you have any concerns over safety,
    then simply fit an RCD inside the house
    this will not only protect the post but also the wiring to it.
    you can never be too safe
     
    • Agree Agree x 2
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