Spotlights Tripping Fuse

[lukegeorge]

In absence of an insulation tester, using a multimeter, then with the circuit off off and the light switch off. and the 4 trans disconnected
Use a multimeter set on continuity and take readings between all combinations of L N and E

You should have a high resistance all ways.
Any low reading would suggest a problem, then you can break the wiring down to sections to find the faulty area.

So I've just tested all 3 combinations across L, N & E against all wires individually in the circuit. The only low reading I got was from the neutral feeding the first light to the earth.

I'm guessing this means there's a join further up the line somewhere. Unfortunately that wire disappears through a joist right next to the fitting so I can't see it. Is there any way of finding where the join is or is it just a matter of lifting floorboards upstairs until I find it?

One other thing that seemed strange to me was when everything was connected in the chain I got a low reading at the second light between N & E but then at the third and fourth light the reading was fine.

 

[333rocky333]

Oh i failed to mention that sorry, the first cable will read low N to E thats normal because that neutral is connected in the consumer unit still to the neutral bar, which in turn will via the mains supply be connected back to earth,
However With the neutrals connected through but no transformers across L and N then you would read this low resistance N to E across all 4 light positions.

From what your saying it appears there may be a problem between 2nd and 3rd