You Do Need power plug adapter while traveling from Equatorial Guinea to South Africa.

Here is Why You Need An Adapter

The outlet and plug type used in South Africa are C, M and N 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

South Africa

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

Type C

Type M

Type N