In article .com,
writes:

Andrew Gabriel wrote:

It's not typical -- I normally find they trip within
20ms at the rated trip current (not used Clipsal though).

Each & every time?

Yes.

It tripped within 16 or 17ms first couple of times,
but trying repeatedly I got non-operations. Maybe the RCD was getting
tired? ;-)
As I say though, I did test on different samples.

Whitfield says "100% of rated ... must ... trip within 200ms" and
"150mA ... 40ms" which suggested to me that a (say) 30mA 30ms RCD
should trip at 30mA, but doesn't have to do so within 30ms, but would
trip within this time at higher currents.

Yes, they aren't required to trip in 20ms at the rated trip current,
but normally they do. However, they are required to trip every time!

Is your RCD tester calibration out of spec?

Just recently been calibrated so I'd hope it'd be OK. Will try again on
other RCDs (like this house cct, after I've logged off :-)

--
Andrew Gabriel