AGE Of INSTALLATIONS

[Piratepete]

I'm often wondering or being asked how old the wiring is, particularly when it's been disguised with new sockets. There are plenty of clues, but I wasn't in the trade when the changes came about. Here are a few to start. Feel free to add dates for other significant changes.

When did main bonding increase from 6 sq mm to 10 sq mm?
When did earths on lighting circuits become obligatory?
When did the earth conductor in 2.5 sq mm T&E increase from 1 sq mm to 1.5 sq mm?
When did stranded T&E for socket circuits disappear and what xsection is it?
When did twisted flex for pendants go?
When did voltage operated earth leakage trips get the boot?
Cheers

 

[Steve Richards]

I'm an old dog with a poor memory so answers may not be that accurate and are estimates.
1. early 1980's (can remember 2.5 off the largest rated circuit - 30A ring main!!!!)
2. Mid 60's (when I started in 69 was using twin & earth)
3. Not sure
4. Changed from imperial approx '70 - '71 and for sockets (2.5 rings = 7/029...7 x 029 of an inch) (4.0 radial = 7/044) (6.0 = 7/064)
5. Mid 70's?
6. Late 60's?

Regards

Steve