Why?kendor said:Certainly the Rad would have been an issue
Why?and bonding would have been attached to the Rad
Why?same with the taps,
Indeed - what about them? That was the whole point of my examples such as the metal tumbler, and the razor handle, and the metal comb.what about the metal fillings in your teeth Ban?
It's madness to have a simple rule of "if it's metal and in a bathroom you should bond it." You have to apply more thought than that.
Please explain the fascination with radiators. (And taps). Let's make some of my questions above non-rhetorical.While i agree that a higher impedance path would reduce the shock, it all seems a bit iffy that you "hope" that the impedance of an unbonded say Rad for instance is high enough not to give a fatal shock, leaving unbonded and unequipotential(if there is such a word) metalwork in a zone makes for a very uncertain installation.
Would you bond items like these:
If not, why not? They are made of metal, and they are screwed to the wall, like radiators are.
And if you wouldn't bond those, then why bond other metal objects that are also not extraneous-conductive-parts? You don't have to hope that there's a high impedance path, you only have to look at the results of the research done - even with a double dose of inhibitor, 15mm plastic central heating pipes have a resistance of over 20kohms/m. Pure water, such as that being supplied to the taps is 115kohms/m.
Assume a worst case wet-body resistance of 250 ohms, then any impedance in a fault path of 7k5 ohms or above produces a fault current of <30mA.
But now we have new ways, of plumbing, and the old ways, of electrics, need to be changed.At least with the "old" way you were certain of equal earth potential and the rest of the regs covered fault conditions such as adequate cpc and fusing to try to prevent a shock hazard.
I can't think of any, other than grossly obvious ones, like cables or appliances falling off the walls, and they are not specific to bathroom zones.Just for a moment think of ways that metalwork in a zone may become live and stay live if all the other precautions had been adhered to.
NO - if you're concerned about the extraordinarily unlikely scenario you mention, then test, because if you bond an otherwise isolated radiator fed by plastic pipes then you have made things less safe, not more.To say that an unbonded piece of metalwork is high impedance without having tested it to see if that is the case leaves a lot of uncertainty who knows if the plastic pipe fed rad isn't already at or near earth potential anyway? Maybe a fixing screw has touched earthed metalwork inside the wall say for instance the metal mesh plasterers use on corners this may be in contact with a switch box? Can you see the point i'm making? better certainty than uncertainty.