High kA & RCD's

Hi All,

Looking for a bit of advice on the following.

We have a DB with a calculated PSCC of 13kA so will install MCB's at 15kA.

From the MCB though, we then will immediately go through RCD's but most of these on the market are rated at 6kA only with some at 10kA. As it is the MCB that provides the short circuit protection and not the RCD, will the 10kA or even 6kA rating of the RCD then be sufficient. 

Also,  if there was a dead short between line & earth, would the MCB not operate before the RCD??

Thank you in advance. 

Mark