IEC 60364 Table 48A

ProMbrooke:

gkenyon:

ProMbrooke:


However, when all is said and done, I think table 41.1 needs to be re-visited again. 

But is that based on the fact that RCDs can't be trusted?


Table 41.1 is dry condition only.


Other than reliance on RCDs to achieve 40 ms disconnection time for additional protection, is IEC 60364 deficient in any other respect?

If all disconnection times are reduced to 0.2 s, what do you propose we do about circuits > 63 A (sub-mains etc.) that currently have disconnection times of 2 s and 5 s (and do NOT align in any way, shape or form to IEC 60479)? How will we achieve disconnection times and selectivity for these circuits?


If Table 41.1 is revisited for these reasons, other parts must be also ... would be good to hear your recommendations and reasoning on these other circuits?

In my opinion, an RCD can fail, and thus are just one layer of the onion.


There is also the fact RCDs are 30ma devices, where the no let go current starts at 10ma. It is possible (in theory) to end up frozen to the source, yet not trip the RCD. For this reason US GFCIs trip around 6ma.

 

In practice I find that U.K. R.C.D.s rated at 30mA, typically trip off at an imbalance of between 20 and 25mA approximately when tested. The time taken to trip off when tested is lower than 40mS.

https://www.bing.com/videos/search?q=john+ward+RCD+testing&docid=608041243210089943&mid=41B22D889B67C22511CB41B22D889B67C22511CB&view=detail&FORM=VIRE


Z.

ProMbrooke:

gkenyon:

ProMbrooke:


However, when all is said and done, I think table 41.1 needs to be re-visited again. 

But is that based on the fact that RCDs can't be trusted?


Table 41.1 is dry condition only.


Other than reliance on RCDs to achieve 40 ms disconnection time for additional protection, is IEC 60364 deficient in any other respect?

If all disconnection times are reduced to 0.2 s, what do you propose we do about circuits > 63 A (sub-mains etc.) that currently have disconnection times of 2 s and 5 s (and do NOT align in any way, shape or form to IEC 60479)? How will we achieve disconnection times and selectivity for these circuits?


If Table 41.1 is revisited for these reasons, other parts must be also ... would be good to hear your recommendations and reasoning on these other circuits?

In my opinion, an RCD can fail, and thus are just one layer of the onion.


There is also the fact RCDs are 30ma devices, where the no let go current starts at 10ma. It is possible (in theory) to end up frozen to the source, yet not trip the RCD. For this reason US GFCIs trip around 6ma.

 

In practice I find that U.K. R.C.D.s rated at 30mA, typically trip off at an imbalance of between 20 and 25mA approximately when tested. The time taken to trip off when tested is lower than 40mS.

https://www.bing.com/videos/search?q=john+ward+RCD+testing&docid=608041243210089943&mid=41B22D889B67C22511CB41B22D889B67C22511CB&view=detail&FORM=VIRE


Z.