Live go's dead when negative is connected (Light Problem)

[Aeon7944]

Hey guys, i was wondering if you might be able to help me out.

So i turned the light on one morning and it made a popping noise and the lights flashed and went out.
The circuit breakers didnt 'pop' out though, so it was a short circuiting issue.
So i got a new light fixture, cabled it back up. When i was testing for current, the live was fine, but when i closed the circuit ( connected the negative ) the live went dead, no current was going through it... Which i thought was pretty weird. So basically when the negative isnt connected to the circuit the positive is live. When it is connected the live goes dead. However there is no short circuit because the main breaker board is breaking.

Any ideas!?
Its just a standard light fitting...

Thanks!

[Besoeker]

Hey guys, i was wondering if you might be able to help me out.

So i turned the light on one morning and it made a popping noise and the lights flashed and went out.
The circuit breakers didnt 'pop' out though, so it was a short circuiting issue.
Thanks!

If the breaker didn't trip, how did you decide it was a short-circuiting issue?