Bought a new setup and just looking through the setup beforehand.

The power supply is meant to indicate the negative with a ridge but mine seems smooth on both. Why couldn't they just use black and white insulation?

On a related note, would be far easier if the power supply connected to the siren back box and then passed power though using pogo pins or a small flylead - trying to feed the wires through the grommet and wire the connections whilst standing on a ladder 20ft in the air and trying to hold the alarm in the other hand at the same time seems a recipe for disaster.