Change "It has been thrown at us " to "XXXXXX told me that" where XXXX is the title or position of the person who said it (man in pub, C&G lecturer, design engineer, plasterer's apprentice).
I think he may be quoting pre-2001 16th edition. The newer regs have gone the way of equipotential bonding as opposed to disconnection times, there are still certain items which require RCD protection and must disconnect within 0.04s @ 5xI/\n and 0.2s/0.3s at I/\n depending on the BS no of the RCD. If the item is fed by an MCB the efli of its circuit should be low enough to ensure a disconnection of 0.1s as in the regs the min current required for 0.1s to 5s disconnection times is the same.
1.4 Protection against electric shock
Bathrooms and Shower rooms
Disconnection times for circuits supplying current-using equipment are no longer 0.4s. However, 30 mA RCDs are to be fitted to circuits of certain items of current-using equipment (see Table 1B)
Not sure if this helps but I posted a similar question recently and this is where it led me.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local