RCBO Test data - 40 milliseconds

[rolyberkin]

Okay may be a thick question but I have an RCD tripping on 5 x test 180 at 40ms. Pass or fail?

GN3 says must not exceed 40ms
BBB says within 40ms
My tester says computer says no.

To be honest I am recommending it be changed anyway but it will be a call back on a new build for another spark so views appreciated. It is a Lewden 32amp rcbo and they normally trip around 19ms.

 

[Deleted member 26818]

40ms @ 5 x Delta is fine.

 

[Risteard]

40ms @ 5 x Delta is fine.

5 I delta n.

 

[Deleted member 26818]

5 I delta n.

Yes.

 

[Wilko]

Okay may be a thick question but I have an RCD tripping on 5 x test 180 at 40ms. Pass or fail?

GN3 says must not exceed 40ms
BBB says within 40ms
My tester says computer says no.

To be honest I am recommending it be changed anyway but it will be a call back on a new build for another spark so views appreciated. It is a Lewden 32amp rcbo and they normally trip around 19ms.

Hi - this is why in maths we've got <=> so we know exactly what's intended. Anyway, I think "within 40ms" should be any number that is not larger than it. So my take is a 40 ms result is a pass, but 40.1 ms would be a fail. This would seem to be in line with GN3 interpretation too.

 

[Richard Burns]

So long as the tester is not showing it tested for 40ms and the RCD had not tripped so that test failed and was stopped at 40ms, but instead the tester was actually showing a time of 40ms for the RCD to trip then I would say this was compliant.
Based on the wording in AMD3 it is compliant, not exceeding 40ms; based on the wording in 18th ed you would just need to increase the test current as it states at or above 5IΔn it must trip within 40ms.

 

[Richard Burns]

Just thinking, there were no loads connected when the testing was done?
On one of my assessments I was testing some Lewden RCBOs and they were way off, 100ms+, because the circuit still had loads connected.
As far as I can tell the trip times when unloaded are consistent at either 19ms or 29ms for almost all Lewden RCBOs I have tested (+-1ms).

 

[Deleted member 26818]

Just thinking, there were no loads connected when the testing was done?
On one of my assessments I was testing some Lewden RCBOs and they were way off, 100ms+, because the circuit still had loads connected.
As far as I can tell the trip times when unloaded are consistent at either 19ms or 29ms for almost all Lewden RCBOs I have tested (+-1ms).

I would be worried about an RCD that doesn’t trip in the required time when there’s a load.
I wouldn’t want to have to switch everything on a circuit off, just so I can be safe when I mow the lawn.