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practical need for supp bonding in bathroom

wallywombat
Can anyone suggest a realistic scenario where supplementary bonding would be required in a bathroom or other 701 location? I'm failing to think of one, although I may be overlooking something blindingly obvious.


It can be omitted as long all three of these are satisfied: ADS in time; RCD present; any extr-c-p connected to main bonding.


If ADS can't be done in time by either MCB/RCD then its not legal anyway.

RCD has to be present anyway.

Water and gas pipes etc should already be main bonded if they introduce a potential.
  • 0
    If, as you say, the chrome pipes are connected to plastic pipes above then they will not be Extraneous-Conductive-Parts so should NOT be bonded. It wouldn't be bonding anyway; it would be unnecessary earthing which is not a good thing.


    The macerator, shower and fan will be plastic, I presume, so that just leaves the radiator as an Exposed-Conductive-Part with nothing to bond it to apart from possibly the light and the water heater.

    Do the light and heater have any Exposed-Conductive-Parts?
  • Former Community Member
    0 Former Community Member
    Thank you very much for your reply Geoff.  No, the light and heater don't have any exposed conductive parts. It just didn't sit well with me but I am very happy not to bond.  I was thinking about Ions conducting electricity through water and going off at a tangent, I needed nudging back into reality, thanks again.
  • 0
    The conductivity of tap water in the UK is quite low, even in hard water areas a meter or so of plastic pipe will probably be 50 to 250kohms or so depending where you are..
    a JW video where he measures it.  It is therefore safe to assume that anything more half a meter will provide the necessary isolation to call the section of chrome isolated.


    I am less sure about radiator water, which after a while may well be rather more dissolved metal ions than the stuff out of the tap, and more conductive, especially with ionic inhibitors intended to make the water slightly alkaline. It might be sensible to assume 10 times worse.
  • 0
    I forgot about the RCDs/RCBOs bit.


    If ALL circuits have RCDs and the other two conditions previously mentioned in the thread are met, then no supplementary bonding is required anyway.
  • 0
    In my house, I once measured between two radiators 3m apart connected via plastic pipe. It was around 300 kOhm. This had the usual rust inhibitors, and it is a soft water area.
  • Former Community Member
    0 Former Community Member
    Thank you for pointing out the JW video. I watched it and even endured the mouthwash ad.  He is a very likeable presenter with an affable manner, I will see what else he has on the web.  He cleared that up for me anyway. Many thanks.

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