You Do Need power plug adapter while traveling from American Samoa to Saint Helena.

Here is Why You Need An Adapter

The outlet and plug type used in Saint Helena is G and in American Samoa are A, B, F and I. This is how they look like.

American Samoa

In American Samoa, outlets of type A, B, F and I are in use.

Type A

Type B

Type F

Type I

Saint Helena

In Saint Helena, outlets of type G are in use.

Type G