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Spacing of multiple earth rods

  • 09-05-2017 11:57am
    #1
    alphonse mephisto
    Registered Users, Registered Users 2 Posts: 65 ✭✭


    Hi guys, I'm not doing a job I'm just curious,

    If a house or building is converted into apartments each with a separate electrical supply at a minium how far apart should earth electrodes be placed apart to avoid any problems?


Comments

  • #2
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    alphonse mephisto wrote: »
    If a house or building is converted into apartments each with a separate electrical supply at a minium how far apart should earth electrodes be placed apart to avoid any problems?

    Normally there would be one electrical supply for the building with one earth pit made up of a number of earth rods (or electrodes). This earth pit would be connected to the MET (Main Earth Terminal) with one or more cables. From a "proximity factor" point of view (how much earth rods would influence each other under fault conditions) the minimum distance between earth rods depends on a number of factors including the resistive of the soil and the length of the earth rod. However, I have generally seen rods spaced at least 4 times their length apart (which is quite conservative). If the rods are too close together then the overall impedance of the earth pit is increased. When installing earth pits where the horizontal conductors are made of 25 x 3mm bare copper tape these conductors achieved more than the rods in terms of reducing the overall resistance.

    If earth rods from separate installations are placed to close together then there is a risk that an earth fault in one installation may cause a use in potential in an other installation.


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