On Friday, 25 September 2020 15:24:49 UTC+1, Max Demian wrote:
On 24/09/2020 21:48, tabbypurr wrote:
On Thursday, 24 September 2020 17:24:20 UTC+1, Max Demian wrote:
On 24/09/2020 12:15, tabbypurr wrote:
On Sunday, 20 September 2020 10:54:40 UTC+1, wrote:
On Sunday, 20 September 2020 10:48:07 UTC+1, Chris Green wrote:

Our house (as in the house I grew up in, back in the 1950s) had a very
early ring circuit as it was built in 1949 or thereabouts. It
definitely had fuses at each end of the ring. Whether that was as it
should have been or just how the electrician (my father I think)
thought it should be I don't know.

When rings were first introduced, people used to make them from 2 15A radial circuits joined together.

I don't know how officially-sanctioned that was or for how long.

It was part of the original rationale for the design.

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

2x 15A fuses running a 30A ring. The point was one could add unlimited extra sockets by joining 2x existing 15A socket circuits into a ring. It was an ingenious solution combining cost cutting with safety improvement.

What if you plugged two 3kW fires into sockets near one of the fuses?

Firstly that's unlikely in practice, and very unlikely for them to run for long.

wouldn't it blow, or at least overheat the nearest fuse? A proper ring
main would cope easily with a single 32A fuse.

The cable would run hot, but not hot enough to be a hazard.
15A BS1361 fuses trip in around 20 seconds at 30A, so it probably would. The user wouldn't notice until the other fuse tripped another 20s or so later.
Some users might then fit 30A fuse wire or a suitable nail, enabling the thing to run indefinitely. It would.


NT