I'm somewhat struggling to think of how bonding is necessary for ADS. Could you perhaps enlighten me?
Kind Regards, John
I do see that for either a fuse/MCB or RCD to operate current must return to the DNO by some route which does not involve the neutral, and to bond does not connect to earth, it just ensures all bonded conductors are at the same voltage.
But in general we are looking for items to be bonded to earth, not just to each other.
Although one could use a long wire and a low ohm meter to test bonding, so many times I read EICR where it says can't find bonding on gas or water pipe, and I wonder why it is not simply tested?
So the scenario. Dog knocks over lamp standard in bedroom, the bulb smashes as it hits the radiator so radiator becomes live, in the bedroom you can see the lamp on the radiator, so one can avoid touching the radiator, but in other rooms in the house the radiators can also be made live, however as long as all other metal in the room is also live there is no path so no danger, however that may be the theory, but in practice the is capacitive and inductive links to ground, so even wearing rubber shoes, if you touch a live part without first using a resistor to equalise the voltage you will still get a shock, so in real terms where pipes or other metal parts can transmit a voltage from one room to another, we want it earthed, so when the dog knocks over that lamp the power is auto disconnected.
I do see in certain places earthing can cause danger, I know in a fitters workshop I used 25 mm² earth cables to bond, as any earth cable smaller could melt if the welding set earth was not correctly attached to the work, but this is hardly a problem in a domestic premises.
The only problem with domestic is where the neutral is lost with TN-C-S however unless there is something unusual like a radio hams earth mat, the problems are not something the domestic installer can do much about.