Another home wiring puzzle

Probably. There was a Part P in 2013 from the Building Regs of 2010. The

That says there was one in 2006, so I guess there might well have been one in 2002.

Nope, it was first proposed in 2005, the first approved document being the 2006 version. The scope would also have excluded any jobs already underway when it came into effect.

Yes. Agreed.

I was making the point that if you put one end of a ring into one RCD and the other end into another RCD the circuit would work (if there are no faults).

Cheers

No, it came in on 1/1/2005

I have twice now come across the arrangement where instead of a 30A/32A fuse/breaker a ring has been wired from a 15A/16A around the property and back to another 15A/16A. That sort-a gives a 30A ring but only sort of.

I discovered it in my current flat over the summer when I was inserting a socket into the ring in the roof space. After checking everything I swapped it for a single 32A breaker. This in a consumer unit with a label claiming the installation had been checked in 2015, just before I moved in and when the flat was refurbished.

jgh

I have something similar here but with 6 ring mains:

Kitchen & Utility room

Front room and the bedroom above it and the office above the kitchen and the landing sockets

Dining room and the bedroom above it

Lounge and the Master bedroom above it and hall sockets

Loft ring main

Garage sockets and all outside sockets

All the houses on the estate where I live were built between 1972 and 1976 and the 2 and 3 bed semis and terraces only have one ring main for the whole house, plus cooker and immersion feeds, but have separate lighting spurs for upstairs and downstairs (with borrowed neutral on 2-way stairs/landing switching).

I thought Part P commenced on jan 1st 2005 ?, though the harmonised cable colours were on sale before then.

If you read the link you gave you'd have the answer to your question

it's not a mistake & doesn't have safety implications.

NT

It was part of the original rationale for the design.

NT

Any slightly high R joint would result in imbalance & trip the RCDs.

NT

It did, I fitted my consumer unit on dec 31st 2004.

They were.

Yup, new colours were permitted before part P and old colours still permitted after it. So, contrary to popular opinion, the colours tell you nothing definitive for dating an install (wrt part P anyway).

Was each circuit fused for the whole ring, or half?

The link given also explains the 4 fuse variant.

NT

What if you plugged two 3kW fires into sockets near one of the fuses? wouldn't it blow, or at least overheat the nearest fuse? A proper ring main would cope easily with a single 32A fuse.

This was covered a few years ago.

Ah, the famous dennis never ending wriggling thread?

I have to say was my thought. Worst case scenario would be live fed through RCD and neutral fed through the other RCD.

Both would see an imbalance equal to the current drawn by the load.