You Do Need power plug adapter while traveling from Cuba 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 Cuba are A, B, C and L. This is how they look like.

Cuba

In Cuba, outlets of type A, B, C and L are in use.

Type A

Type B

Type C

Type L

South Africa

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

Type C

Type M

Type N