Ring main consisting of only spurs

[Pete999]

Such circuits with imperial cable and spur drops off the upstairs sockets are fun unless you have sockets that can accept 3 x 4 mm cable

Why 3 times 4mm2?

 

[Pete999]

Probably due to the ground floor being a solid floor, far easier to run the ring in the first floor, drop down to sockets on the ground floor as spurs,and the sockets on the first floor are part of the ring. That's how we used to do it in the olden days, 7/029 twin and earth, lots of 30 Amp JBs.

Of course nowadays you would need poncy MF joint boxes, whereas many of today' s Domestic Guys aren't taught how to make off a proper JB, just bung the cables in a MF JB. No sign of a platform between the joists to keep the JB stable, or cable clips for that matter, art has gone from our trade, bung it in, glue the flooring down, and forget the joint, cuz it's MF, until, da da Murphy's law comes into play, if you don't know Murphy's law, " what can go wrong, will go wrong"

 

[Pete999]

Probably due to the ground floor being a solid floor, far easier to run the ring in the first floor, drop down to sockets on the ground floor as spurs,and the sockets on the first floor are part of the ring. That's how we used to do it in the olden days, 7/029 twin and earth, lots of 30 Amp JBs.

Of course nowadays you would need poncy MF joint boxes, whereas many of today' s Domestic Guys aren't taught how to make off a proper JB, just bung the cables in a MF JB. No sign of a platform between the joists to keep the JB stable, or cable clips for that matter, art has gone from our trade, bung it in, glue the flooring down, and forget the joint, cuz it's MF, until, da da Murphy's law comes into play, if you don't know Murphy's law, " what can go wrong, will go wrong"

 

[Deleted member 26818]

Have seen these in Warner type flats, where the circuit only supplies the upstairs flat (as far as I am aware).
Landlord wanted to lease to the Local Council and had to add a couple of extra sockets.
Wanted as little disruption as possible.

 

[Octopus]

Why 3 times 4mm2?

Old imperial cable has a greater cross section than 2.5 mm cable

An "old" installation with a ring around the top floor and spurs down to the socket below means each socket will have 3 cables

Therefore the sockets need to accommodate 3 x 4mm cables .... as they are very unlikely to accept 3 x imperial cables ...

 

[Pete999]

Old imperial cable has a greater cross section than 2.5 mm cable

An "old" installation with a ring around the top floor and spurs down to the socket below means each socket will have 3 cables

Therefore the sockets need to accommodate 3 x 4mm cables .... as they are very unlikely to accept 3 x imperial cables ...

Dead easy to get 3 times 7/029 into a socket terminal, now 7/036 or 7/044 would be different 7/029 easy peasy. Remember 7/029 is stranded, 4mm2 is solid, and 7/029 is the closest Imperial size to 2.5mm2 cable, 3/029 would be to small 7/036 = aprox 4mm2

 

[telectrix]

worst thing was with the 7/029 was muppets twisting 3 cables into a demented corkscrew then forcing into a terminal that would only just accommodate them. usually by snipping a few strands off.

 

[Toneyz]

When I started out all the sockets had a nice large bellmouth terminals Contactum for one.

 

[telectrix]

yep.they were 15A round pin jobbies. built like a brick shiithouse. never any poor contacts ( and you could wedge wires in with rawlplugs),

 

[Pete999]

worst thing was with the 7/029 was muppets twisting 3 cables into a demented corkscrew then forcing into a terminal that would only just accommodate them. usually by snipping a few strands off.

Agree, but done carefully you could manage ti get three in a terminal on a socket

 

[ipf]

Not quite the same, but I remember wiring a council office, two large downstairs flats knocked into one, concrete shell with suspended ceiling . Wired it to spec....and then they changed it all, offices and large kitchen. Trouble was, they wouldn't let us rewire because it was mostly ready for 2nd fix. There were loads of socket points all to be moved. Broke into the ring at every point and fitted 2 x 30 amp JB's. There must have been fifty odd JB's on four rings, all Clerk of Works approved.
Never any comebacks, though.

 

[Timbo]

My senior lecturer at college in late 80's always propounded that theory. He was going to rewire his bungalow like that. He said a jb was no different from having a socket in the same location.

 

[Octopus]

My senior lecturer at college in late 80's always propounded that theory. He was going to rewire his bungalow like that. He said a jb was no different from having a socket in the same location.

Except you wouldn't have sockets under the floor...

 

[Timbo]

He didn't have a floor in his roof