Can this be placed outside?

I would not use this where it could get wet.

Only perhaps if it's sheltered from the elements, like a carport or shed. You wouldn't want it exposed to rain.

If in a covered area, yes. However, it would not do well if exposed to the elements.

If the two plates short then it can damage the unit. So in the weather probably isn't the best place for it. Maybe somewhere elevated and covered. Mine is in my chicken coop

All of our electronic mouse/rat traps are designed for indoor use only.