Identifying Existing Mods

[cirks]

Hi, first post so hope someone can help.

We've just moved house and I am looking at adding a number of additional sockets. My first 'project' is the study where I need to add probably at least 8 sockets (ie 4 doubles). I was going to do this by extending the ring ideally using existing single socket.
However, last night I got the floorboards up to discover a couple of junction boxes already exist. So, I know I'm asking you to guess but can anyone give me an informed opinion as to what has already been done if I describe some of the connections?

Cable from next room goes into JB1 and exits to JB2. From JB1, a cable goes to the single socket. This socket has a 2nd cable exiting to somewhere else (ie under the landing where I haven't got the boards up yet). From JB2, there are 3 cables (in addition to the one coming/going to JB1). One cable goes again towards the landing. One cable I have traced to the outside wall coming from downstairs (connection to downstairs ring?).Third cable looks like it may also go downstairs or poss to other room (can't yet get to other end).
If you managed to draw that, any ideas?

?--1->JB1---2-?Socket--3--->?
|4
?>-5--JB2--6--->?
|7
v
Downstairs

[vertival bars should be under the JBs]


The main CU only has one fuse for the Ring Main (ie there is no Upstairs Ring and separate Downstairs Ring).

[plugwash]

first of all disconnect any significant loads from your ring

then turn off the ring and disconnect all 5 cables that leave your junction box arangement and terminate them temporerolly to sockets

then turn the ring back on and plug a lamp into each of them

if it lights from two of them you almost certainly have your ring cables and should be able to work from there

if it lights from just one of them you have a huge mess hung off a spur or a broken ring (you can test for a broken ring from the CU by disconnecting the two cables to the cuircuit and using a multimeter to test for continuity from one end of the ring to the other)

if it lights from more than two of them then come back for further advice

[cirks]

First, thanks for the reply. Sorry if I'm being a bit slow but....

plugwash wrote:

then turn off the ring and disconnect all 5 cables that leave your junction box arangement

Which 5? Do you mean effectively removing any additional cables other than the 'straight through' ones from the 2 JBs? I've edited my original post to number each of the cables - can you reference these when saying which ones to disconnect? Thanks. (I realise that a couple of the numbered bits are going to be continuations of another bit but thought this would be easier)

Quote:

and terminate them temporerolly to sockets

do you mean put sockets on the ends of the cables removed?


I also meant to say that I had tested both cables from the single socket and it doesn't look like it is a spur.

[plugwash]

assuming this is how you mean your diagram to be

Code:

?--1--JB1---2-?Socket--3----?        |4 ?--5--JB2--6----?        |7        v

so cables 1 3 5 6 and 7 leave your arangement to go to other parts of the house

you need to figure out which of theese 5 are the ring cables and the easiest way to do this is to disconnect all of them from your arangement and connect them teporerally to sockets

then turn the power back on and find out which two of the temporary sockets are functional theese two are your ring cables the rest are spurs

if you get a number other than two of them functional you have a much bigger problem

[cirks]

thanks again. I'll do this tonight and let you know the outcome.

[p.s at least I now know how to include lovely ascii drawings in a post ]

[cirks]

Well, you're a star plugwash! Did as you said and discovered just 2 (fortunately) live. In the numbered drawing, the ring cables are no. 3 and 5. So, I've extended the ring from 5 to the first of the new sockets and rejoined to JB2 from the last of the new sockets.

Based on the above, I assume 1,6,7 are spurs. However,as I don't know where they go yet I've no idea how many sockets are attached to them No doubt I'll find that out once a few more boards are up!

I only found the forums a couple of days a go and boy am I glad I did...Thanks again.

[ban-all-sheds]

cirks wrote:

Based on the above, I assume 1,6,7 are spurs. However,as I don't know where they go yet I've no idea how many sockets are attached to them No doubt I'll find that out once a few more boards are up!

Or alternatively you could disconnect them 1 at a time and see which sockets no longer work...

__________________
I mustn't warn people that the "experts" on the plumbing forum can't be trusted to tell the truth.

[cirks]

ban-all-sheds wrote:

Or alternatively you could disconnect them 1 at a time and see which sockets no longer work...

there I go again, missing the bleeding obvious solution Interestingly, if there are multiple sockets running off the (potential) spurs, would you suggest I leave them or go to the hassle of getting the floorboards up and changing them in to an extension of the ring? If I need to add sockets to a room served by a spur then I assume I need to do the latter anyway if I want to comply with IEE regs?

As a followup, since a number of the new sockets will be providing power to PCs etc which option do you think is best:
1) socket providing power to a surge protected multiblock extension lead
2) normal sockets with equipment plugged straight in
3) special surge protected wall/surface sockets (if there is such a thing)
4) some other solution?

Options 2/3 I think would be the neatest solution (ie saves yet more cable under the desk) but is 1 the best?

[ban-all-sheds]

There is such a thing:



Screwfix product code 10502.


Extending the ring is always best, but if you can't do that, put each spur on a 13A FCU.

__________________
I mustn't warn people that the "experts" on the plumbing forum can't be trusted to tell the truth.

[cirks]

um, that leaves me with the decision whether to spend £18 per double socket or £28 for an 8 socket surge protected extension lead....! So, do I go for looks or value ?

[fubar]

cirks wrote:

So, do I go for looks or value ?

How soon do you plan to move and would you be happy to leave the socket or would you put back the standard ones?

--
Michael

[plugwash]

if the spurs run multiple sockets then provided they are not running heavy loads just start them from unswiched fused connection units

[cirks]

fubar wrote:

How soon do you plan to move and would you be happy to leave the socket or would you put back the standard ones? Michael

After the stress of this move I can't see that we will move again for an awful long time!!

[cirks]

Quick question on junction boxes: in my interesting setup shown above, the junction boxes are both 4 terminal yet I can't seem to find 30A 4 terminal jbs listed now (ie not in Wickes, TLC, Screwfix). Does this mean specs have changed or that the boxes are not 30A (yes, I know it probably states what they are on them but I'm not at home at the moment!)

[dingbat]

You only need three terminals in a 30A junction box, unless you are wiring up some pretty heavy duty lighting. The fact that you have four-terminals in yours is probably a good indication that they are in fact 20A boxes. If so, change them.

(The fourth terminal is normally used for the switched live when wiring up lighting by the 'junction box method'.)