Thread: RCD trip times
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BigWallop
 
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oups.com...
Testing an RCD (part of a split-load CU) I found that at the rated
current (30mA) it would trip anywhere between 16-17ms to not at all
(even with the meter set to the 2s range). Suspecting the RCD I swapped
in another from a spare box (same make - Clipsal - but almost certainly
different batch as I bought them at different times from different
suppliers). However the other RCD showed much the same behaviour. Both
tripped reliably at 50mA.
Is this typical, or are both faulty? (Is Clipsal crap? :-)


When was the test meter last calibrated? Is the battery still good, or is
it a mains operated test meter? It could be your meter and not the RCD's
you know. The most reliable test gear is connected across the supply and
doesn't rely on a battery.

The mains operated test meters have crimp ends which connect with main
supply leads to the RCD switching. Then the test leads are connected across
the consumer side of the same switch. It then slowly increases the current
to a point where it causes the RCD to trip out. They then store the info'
on the display for easy reading after they're disconnected. They do have a
battery to make the display work and keep the NVM chip working after
disconnection, but they don't rely solely on a battery for the full test.

They're also very expensive, especially if you have to buy three like we
did.