You Do Need power plug adapter while traveling from Equatorial Guinea to Pitcairn Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Pitcairn Islands is I and in Equatorial Guinea are C and E. This is how they look like.

Equatorial Guinea

In Equatorial Guinea, outlets of type C and E are in use.

Type C

Type E

Pitcairn Islands

In Pitcairn Islands, outlets of type I are in use.

Type I