As I understand it then for my PIRs I should refer to the main switch in the old rewirables as a 5419, and in a modern it'ss a 60947-3?
Yep, normally the new ones will have either 60947-3, IEC 947 or something similar stamped on them, the old ones are more tricky. The rule of thumb I would go by is that if there's nothing on it, then it'll probably be a 5419.
the rating is variable, 60-80?
I'm not sure if the rating is variable. I think the smaller old Wylex are rated at 60A, whilst the bigger 8-10 ways are 80A.
I dont want to appear dense, but pevvers, could you elaborate on the enclosures comment and the reference to BS 5486? What do you mean by the enclosure, the box of the DB?
You're not appearing dense in the slightest. It's only because I had a quick search for BS5486 through the standards and saw that it was superseded by BSEN 60439, which is one I am familiar with. As far as I am aware it relates to the overall safety of the enclosure and all associated equipment, so the case, MCB's, switch disconnectors etc., etc. It means that it has been type tested and conforms to many different tests to ensure that it stands up to whatever may be thrown at it throughout its lifetime.
I am no expert on type testing as I have no need to get into it as of yet (although I now have access to most British Standards so may have to change that), so I will happily concede to whoever knows more, as I am here to learn like the rest of you too!
-----------------------
The abstract text from BS EN 60439-3 is: -
"Gives supplementary requirements for such enclosed distribution boards (DBU), which are stationary, type tested assemblies (TTA) for indoor use, containing protective devices and intended for use either in domestic (household) applications or in other places where unskilled persons have access for their use. Control and/or signalling devices may be included. They are for use on a.c. with a nominal voltage to earth not exceeding 300V. The outgoing circuits contain short-circuit protective devices, each having a rated current not exceeding 125A with a total incoming load current not exceeding 250A. The nominal voltage to earth in an IT system is taken as the nominal voltage of the system."
Make of that what you will, but I shall see if I can actually read the full standard this late at night.... It's probably not looking good though!
--------------------------------
Right, blah blah blah. Yes, it seems to be just the type testing of the enclosure and related bits and bobs. It's not easy to read but I can't seem to see anything more in it than that! I hope I've helped,