Bathroom Pull Switch with Extractor

[BobtheBee]

The bathroom pull switch has stopped working. It also starts an extractor fan that runs for several minutes after the light is switched off.
There are 3 wires to the switch. A thickish Black, a thickish Red, a thinner Red, and an earth.
The new switch an MK6Amp 2 Way has Com, L1, L2 terminals.
I thought I had remembered correctly, and connected the Black to the Com, and the 2 Reds to L1.
When I put the trip back in, there was a bang, and it tripped out.
Now I'm just confused as the printed instructions with the switch don't help, and my call to a local electrician seems to have been ignored.
Help!

 

[Spark123]

There is no steadfast answer, you'll need to find out what cable does what. Was there an indicator on the old one? Can you can trace where all the red/black cables run and see if the black is connected to neutral?

 

[BobtheBee]

No too complicated to trace wires, electrician has now rung and will be calling to fix problem on Monday.
Thanks anyway.