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

Here is Why You Need An Adapter

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

Tanzania

In Tanzania, outlets of type D and G are in use.

Type D

Type G

Ireland (Eire)

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

Type G