You Do Need power plug adapter while traveling from Switzerland to Ireland (Eire).

Here is Why You Need An Adapter

The outlet and plug type used in Ireland (Eire) is G and in Switzerland are C and J. This is how they look like.

Switzerland

In Switzerland, outlets of type C and J are in use.

Type C

Type J

Ireland (Eire)

In Ireland (Eire), outlets of type G are in use.

Type G