RCD Disconnection query - pondering

[Dave Rudderham]

As an interested and pondering student, I noticed an "error" today that my tutor is unable to clarify to me. In the big yellow book, table 41.1 shows Maximum disconnection time on a TN system at 230v~ is shown as being 0.4s, yet 415.1.1 states "an operating time not exceeding 40ms."
If my maths recollection is correct, 0.4s is 400ms, not 40. Anyone know why, or it just such a negligible amount no one is bothered.

thanks

 

[SparkyChick]

The maximum disconnection time of 0.4s is the maximum disconnection time required for a final circuit. For a distribution circuit it's 5s.

The 40ms is the maximum operating time for RCDs when being used for additional protection.

Or at least, that's my understanding.

Edit:- In short, it's not an error

 

[Dave Rudderham]

The maximum disconnection time of 0.4s is the maximum disconnection time required for a final circuit. For a distribution circuit it's 5s.

The 40ms is the maximum operating time for RCDs when being used for additional protection.

Or at least, that's my understanding.

Edit:- In short, it's not an error

ahhhhhhh