S
sparksburnout
I could do with some expert advice on equipotential bonding please, as something is nagging me. Now, I understand the practical side of bonding, and can see that having all extraneous metal tied down to the same potential (earth hopefully) will prevent a person being subject to shock currents if they touch the metal casing of, for example a cooker that has developed a fault where a live conductor within it has touched the chassis, at the same time as if they touch extraneous metal. I understand that the metal of the cooker can rise in potential before ADS cuts off the supply, and that if we didn't have bonding that the difference in potential between the faulty cooker and another mass of metal could allow dangerous currents to flow through the victim. I also understand that various metal must be tested to see if it is extraneous or not. What is nagging me is that, in the event that a person inadvertently touches a live conductor (say if an appliance had smashed or they stuck their finger in a lamp-holder) and extraneous metal, this will provide a perfect path to earth for the current and be worse under those circumstances than if it was not bonded. In other words, the exact opposite of a non-conducting environment? Am I missing something or is it deemed that the chance of this scenario happening is much less than the cooker one?
On a related theme my mate has a completely wooden (large) shed come summer/house that is about 30M from his house. Currently he has it powered by a 3 core flex slung through his hedge (I know makes your eyes water). Am I correct in assuming that if this were done using buried SWA that the armour of it should be earthed at the house end only, and that at the shed he should have an earth electrode, to give it it's own earth, because you are not allowed to extend the DNO's earth out of the building it was intended for and that his shed should be TT?? His house supply is TNS. If this is correct, would I be correct in assuming that this is because there could be a difference in the potentials of earth between the buildings and you need a local earth? I am aware this would be notifiable I am just trying to get him to sort it out!
On a related theme my mate has a completely wooden (large) shed come summer/house that is about 30M from his house. Currently he has it powered by a 3 core flex slung through his hedge (I know makes your eyes water). Am I correct in assuming that if this were done using buried SWA that the armour of it should be earthed at the house end only, and that at the shed he should have an earth electrode, to give it it's own earth, because you are not allowed to extend the DNO's earth out of the building it was intended for and that his shed should be TT?? His house supply is TNS. If this is correct, would I be correct in assuming that this is because there could be a difference in the potentials of earth between the buildings and you need a local earth? I am aware this would be notifiable I am just trying to get him to sort it out!
