testing for borrowed neutrals

[scottg]

on changing fuse boards has anyone got a sucssesful method of testing for borrowed neutrals before changing ?
finding probs on changing boards then to find borrowed neutrals on two way lighting on stairs and wall lights
thanks for any feedback !

 

[GaryMo]

Make sure switches are in the ON position and lamps are in circuit. Measure resistance between line conductors (neutrals disconnected). If there's a borrowed neutral then you may see a low resistance reading though connected lamps.
It's not fool proof but it's a start.

Number of line conductors compared to neutral conductors?

 

[Taylortwocities]

Very tricky. Many times you will not see it when testing. Imagine a neutral from a ring final has been borrowed for an additional light (v.common this one). If the light circuit is switched off you will not see this when testing.

You find it after you've swopped the board and someone turns the darn light on.....

 

[superdaz]

I am guessing you are wanting to know if you have a borrowed neutral before you start the job. probably because you are changing the mains board to new 17th edition dual rcd and this results in both rcds tripping when you turn the landing light on. When i go to look at a job i pull the fuse to the upstairs lighting circuit then see if the landing light is still on, if it is then this is evidence that the live is from the downstairs circuit and the neutral from the upstairs. I then look at how difficult it is to get a neutral from the downstairs circuit upto the landing light and then add this into my quote. Hope this helps