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

Here is Why You Need An Adapter

The outlet and plug type used in Ireland (Eire) is G and in South Africa are C, M and N. This is how they look like.

South Africa

In South Africa, outlets of type C, M and N are in use.

Type C

Type M

Type N

Ireland (Eire)

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

Type G