As others posted, press the test button. It duplicates a
dangerous condition to humans; tests the GFCI. If the GFCI is
OK, then it will trip.

However newer GFCIs have an even better advantage. Should
the GFCI fail, then the circuit cannot be restored until the
GFCI is replaced. Like everything else electronic in the
house, the GFCI can be damaged by external transients - ie
lightning. Then when you needed the protection most, the GFCI
would not be working. That is unless you periodically press
the test button.

In the meantime, new GFCIs now have a safety lockout
feature. If the GFCI in the box trips, then the GFCI outside
also must be reset - and in that order.

Robert11 wrote:
Hello:
Moved into a 30 yr old house that has, apparently, one circuit going
to an outside outlet having a GFCI circuit breaker in the main
service panel.

Being so old, I have doubts about how good the GFCI circuit breaker
may be, but really don't want to play with the panel and replace
the breaker.

Any reason not to just add an additional individual GFCI outlet in
place of the outside outlet there now (leaving the circuit breaker
in the service panel alone) ?

Guess I'm asking if there is any harm, or potential problems, in
having two, possibly both being functional, GFCI devices on a
single branch line ?

Thanks,
Bob