JET2IMPRESS - Why do you assume that there will be fire if you evacuate? I can think of many reasons why slides would be deployed without fire being present.
For example - Nose gear collapse ( southwest airlines yesterday ) no fire present but still evacuated as the attitude of the aircraft did not allow the safe positioning of steps to disembark pax.
Do not assume that there will be fire to ' light your path' away from the aircraft!!
I might also add thet the APU will never be running in an evacuation so the cabin will only have the emergency lighting as a power source, so always assume darkness.