Reported content: Post in thread 'Domestic - RCD tripping- earth neutral fault'

[Jack898989]

Post in thread 'Domestic - RCD tripping- earth neutral fault' by Guest has been reported by Jack898989. Reason given:

Stupid

Content being reported:

This is the last thing I want to happen to me in the middle of the night (this of course happens in the middle of the night, I have explained later)
You may be already knowing that if there is a live earth fault there it is easy to isolate it by switching off all the MCBs and switching them on again one by one while the RCD is on position. As soon as you switch on the faulty MCB the RDC goes to off. Then you can Isolate the problem in that section and repair it.

But earth neutral fault you can never be isolated like that as the neutral is common and originates from a common hub just after the RCD.

How to Diagnose earth to neutral fault? as I said it is difficult, if you can not isolate a Live to Earth fault and RCD trips while all the MCBs are off position; two things are possible 1) Malfunctioning RCD 2) Neutral to Earth fault. you can confirm a malfunctioning RCD by removing both live and neutral of the MCB side if the RCD still goes to off while above both connections are disconnected that means RCD faulty, If you can turn on the RCD while both wires (of MCB side ) are disconnected and the connect only live or neutral separately one by one. You will see that RCD goes to off with the neutral.

Causes of neutral to earth fault? Most possible cause rat bitting and short circuiting a three core wire with Live Neutral and Earth running together (rat bites and short circuit Neutral and Earth) (there is a chance that affected people may have experience tripping in the middle of the night several times before they start full black out one day) (why ? as and when rat bites the live wire the RCD goes off saving the life of the rat).

That is why this is most of the time happening in the middle of the night!
Isolating the place is very difficult? think about possible places vulnerable to rat attack! Specially did you recently block a rat entry hall close to a three core wire?
other method need expert on this field. Turn off main switch take a multimeter and measure the resistance between Earth and Neutral of a normal plug point
(normally it is around 2-3 ohms if there is a Neutral to Earth fault ) check all the other plug points you will get minimum resistance value as and when you are closer to the fault. It is a very costly time taking procedure as you are looking for a wire damage which may even be smaller than 1 inch !

Rats cut off my Satellite LBN wire for blocking an entry point to a rat hole? can they think like humans?

 

[westward10]

That post is 13 years old.