Radials in old houses

[ericmark]

I have been trying to sort some problems in my daughters house and I have found most of the sockets fed by a single cable.

Tracing these cables as far as I can they all seem to return to the CU as if the house has been built with a host of radials but looking in the CU there are just three cables connected to a 32A fuse.

This has me scratching my head as I wonder how and where all the radials are connected together.

With spurs one has a distance limit of 3 meters and technically as feed from 32A fuse I suppose these should be called spurs and some mods to the system are required but other than knocking off the plaster in area of CU and removing the wood panelling it is impossible to see how these cables have been terminated so until they are ready for major re-decorating I can't investigate further.

House has standard 4 way Wylex box with wood back so quite old house around 1960's wiring seems A1 except for odd layout.

Has anyone seen this layout before? Any ideas as to how so many 2.5mm T&E are reduced to three cables were there any junction boxes sold to connect radials this way.

The wiring does seem original not later add on but not seen this before. I have changed 32A fuse wire to 20A for now but at some point I need to do something any ideas of how houses were wired in the 60's

I have wondered if the consumer unit has been moved and if there is some hidden JB in it's old location?

 

[Space cat]

You can get junction boxes that will take three 2.5sq mm cables and, if you think about it, you must have some hidden in there somewhere. Every piece of wire has two ends!

My first step would be to identify which sockets are on each of the three cables that you can see at the CU. Take them out one by one and see what stops working. Don't just look for sockets. You might find some other stuff as well, like a light fitting - with or without an FCU!

Next, go to those sockets that have more than one cable. Use the same trick to determine which other sockets are fed from them. Sometimes you can get clues from visual inspection of the cable. Unless it all came off the same roll, there may be subtle differences between different lengths.

At this point you will probably conclude that you have hidden junction boxes, but where? Here's a test that will narrow their positions down a bit. You will need a good voltmeter.

With no load on the circuit, measure the voltage at the CU and at each socket on one of the three cables. All readings should be the same. Now plug a heavy load into one of the sockets and measure again. You can expect to see a voltage drop between CU and the loaded socket but also note the drops at other sockets. This will give you a rough idea as to where they tap in along the cable run.

Example: You observe a 1V drop between CU and the loaded socket. The drop between CU and an unloaded socket is only 500mV. This tells you that the unloaded socket branches off midway between CU and loaded socket. Better still, if several unloaded sockets all show EXACTLY the same voltage, it's a fair bet that they all converge on a single junction box.

To get an even better idea of wher the JBs might be, repeat the test with the load in different sockets.

 

[RF Lighting]

I think I have heard of an octopus setup around that time.

One big junction box in the centre of the stairs, and a cable out to each socket.

Never come across one my self though.

 

[1john]

I think I have heard of an octopus setup around that time.

One big junction box in the centre of the stairs, and a cable out to each socket.

Never come across one my self though.

yup, big grey square box on landing, feeds lighting and sockets.

although i seem to remember the lighting not being earthed or was it rubber cables that were used when i replaced one. thought it was a good idea at the time before all the ranting about concealed junction boxes, easy to fit awkward lights as there is only one cable in them, sockets with only one cable in are easy work and due to the short runs of cable from a central location all the readings were low.

 

[RF Lighting]

There is one estate near me where all the lights were done on an octopus, but never actually seen it done on the sockets.

 

[sparkwright]

have encountered 60s bungalow where a ring was run in the loft serving many 30A JBs; and each JB supplied a spur which fed a socket down below. every socket in the house had one cable at it.

i don't know if this was standard practice for a while, but it was more trouble than it was worth so it was rewired.

 

[ban-all-sheds]

http://www.madeinshrewsbury.co.uk/companies/hartleys


They did round ones too.. http://www.state-it.com/leccybits/hartley_octopus.html

 

[ericmark]

Thank you now I know what I am looking for. Looks as if I'm going to have fun and no local cut so son can't moor up close to my daughters not sure I'm up for a house rewire I think new consumer unit and separate RCBO on each radial is way to go.

Thank you for info I have not done that much house bashing Power Stations, Air Ports, and petro-chemical what what I spent most of my time on.

All best Eric GW7MGW

 

[Steve]

truly a thing of beauty and skill.

 

[Click-Sure]

Yeah, found a couple around Tamworth, there's a housing estate not far from me with them installed, but no longer in use, owing to rewiring.