As some may know, 
I am a great enthusiast of RCBOs.
I was today testing three RCBO circuits, and was surprised to find that at 30mA they all tripped at about 45ms instead of 30mS as I had expected. I checked my tester against a plug-in RCD adaptor and a 100mS delayed RCD, and got about a 22ms and a 100 ms time as expected.
They did not trip at 15mA or 20mA, which is correct.
At 50mA they trip in 30ms, at 100mA they trip at 25ms, at 150mA and above they trip in 20ms or slightly less.
They are MEM AH30 Pods, and although a few years old, have been in clean dry conditions.
I had a look at the catalogue, where all it seems to say about timing is that they should trip within 40ms at 150mA (and they easily meet that), and it says that this will meet the IEE/BS condition of sockets feeding portable equipment outside the equipotential zone.
Was I wrong to expect a 30mS trip at 30mA? I might have got the idea from RCD sockets, which generally do.
I understand that outdoor sockets have to trip in 40ms so does that mean these RCBOs are not good enough?
Edited: By further reading I now understand that the 40ms is at 5I (so, 150mA in this case) and it seems I had misunderstood the requirement which in this case is met
and I then found it in one of my books once I knew what to look for.
I am a great enthusiast of RCBOs.I was today testing three RCBO circuits, and was surprised to find that at 30mA they all tripped at about 45ms instead of 30mS as I had expected. I checked my tester against a plug-in RCD adaptor and a 100mS delayed RCD, and got about a 22ms and a 100 ms time as expected.
They did not trip at 15mA or 20mA, which is correct.
At 50mA they trip in 30ms, at 100mA they trip at 25ms, at 150mA and above they trip in 20ms or slightly less.
They are MEM AH30 Pods, and although a few years old, have been in clean dry conditions.
I had a look at the catalogue, where all it seems to say about timing is that they should trip within 40ms at 150mA (and they easily meet that), and it says that this will meet the IEE/BS condition of sockets feeding portable equipment outside the equipotential zone.
Was I wrong to expect a 30mS trip at 30mA? I might have got the idea from RCD sockets, which generally do.
I understand that outdoor sockets have to trip in 40ms so does that mean these RCBOs are not good enough?
Edited: By further reading I now understand that the 40ms is at 5I (so, 150mA in this case) and it seems I had misunderstood the requirement
which in this case is met Thanks to Spark123 who in a different topic this evening said:
and I then found it in one of my books once I knew what to look for.
