ring main looping back through sockets

[trevw]

Hi,

I'm looking at the electrics upstairs in the bedroom (will be adding new sockets) and the sockets either have 4 cables connected to the face plate or 2 connected and one going through. It looks like the ring is done with two cables going out along one route and then connecting together at the last socket.

Is this fairly normal? seems fine in theory, especially I guess if alternate cables are used at each socket but I was wondering about ring continuity where all four cables are connected to the same face plate? (i.e. both sides of the ring are connected to each other and then the ring continues on round the room.. is this okay or do I need to disconnect two of the cables from the plate and join them directly to make the ring back into a proper loop rather than a 'figure of 8'

thanks

Trev

 

[securespark]

No, it's not normal at all.

A true ring has two cables at every point along the circuit. There may be a point with 3 where a spur has been taken (or one where the spur cable arrives at a point), but never more or less.

 

[trevw]

should I look to rewire it completely? I was hoping not to have to..

have you ever seen it done perhaps where due to the fabric of the building it is hard to run the 'return leg' of the ring

 

[plugwash]

you shouldn't need to rewire but you do need to sort out the figure 8 nature of the ring and preferablly balance the sockets between the two legs (they don't have to be perfectly balanced but you should try to avoid having them all on one leg.

my advice

first draw a diagram of the area the cuircuit serves with all the socket points on, this will help you guess what cables go where and will serve as a place to record the information you find.

disconnect the cuircuit from the CU. Then remove all the sockets on the circuit. Once you have done this short all the cores of one cable end and use your multimeter on continuity to find the other end of that cable. Label the ends of the cable and record it on your diagram

then unshort the end you shorted, short a different unshorted end and repeat the process.

Once you have drawn a diagram of your cuircuit you can then work out how to connect the wires in a way that produces a single reasonablly well balanced ring.

 

[Steve]

have you ever seen it done perhaps where due to the fabric of the building it is hard to run the 'return leg' of the ring

Yes. there, A radial is used.

 

[trevw]

you shouldn't need to rewire but you do need to sort out the figure 8 nature of the ring and preferablly balance the sockets between the two legs (they don't have to be perfectly balanced but you should try to avoid having them all on one leg.

thanks for the advice plugwash.. when connecting back up to keep the ring balanced, where both cables are going through a single socket how should I connect the cable that is going to continue through? can I use choc block or is there a better way?

ta

Trev

 

[trevw]

Yes. there, A radial is used.

makes sense..

 

[davy_owen_88]

where both cables are going through a single socket how should I connect the cable that is going to continue through? can I use choc block or is there a better way?

You can use a terminal block, but crimping is a better alternative and replacing the cable entirely is better still.

Davy

 

[trevw]

thanks all, will look at how bad it would be to replace the cables with a fall back of crimping..

also just want to thank all the experienced people on here for giving up their time to answer questions. I've made several posts recently and all have had helpful responses.. great forum

cheers

Trev

 

[breezer]

some times (and i mean sometimes) it is easier to rip sometthing out and do it as it should be done than to try and figure out how it is done.

 

[trevw]

thanks for the advice, am replacing the cable and breaking it into a normal ring as it doesn't look too difficult what with the extra sockets I'm putting in anyway..

however I'm now curious and I wonder if someone can explain as I think it might deepen my understanding of why rings are used... from what little I know of electricity I would have thought that if you ran two cables along (and used each cable alternately for sockets as seems to be the case mostly here from what I've uncovered) then wouldn't that just be a balanced ring circuit? Also, if you half way out on that 'flat ring' connected both sides of the ring wouldn't that cause a 'forced balance point' where curent on the other side of the 'pinch point' would be drawn equally from each side of the circuit..? (in case you can't tell I struggle a bit to understand AC currents fully )

obviously not important as I'm changing it but was just curious..

thanks

Trev

 

[davelx]

Nothing specific to AC here - just Ohm's and Kirchoff's laws - full discussion here:

//www.diynot.com/forums/viewtopic.php?t=81877

 

[trevw]

interesting read, thanks.. and explains why a long return leg is a bad idea..

what was said there would seem to suggest to me though that in the case where the theoretical flat ring above was 'pinched together' to make a figure 8, the current would from that point be perfectly balanced back to the CU?,

going further if you took a pair of cables and broke both at every socket like a radial just with two 2.5mm T+E wouldn't that be like an ideal ring in the way that current flowed down it? load would have to be perfectly balanced between each cable?

Am sure I am missing something but as mentioned this has piqued my curiosity

Trev

 

[plugwash]

interesting read, thanks.. and explains why a long return leg is a bad idea..

what was said there would seem to suggest to me though that in the case where the theoretical flat ring above was 'pinched together' to make a figure 8, the current would from that point be perfectly balanced back to the CU?

provided the two legs from the pinch point are the same length yes it would.

the danger is that someone will extend the ring making the pinch point non-central. There is also the fact that such a cuircuit cannot be tested in the same way as a normal ring.

going further if you took a pair of cables and broke both at every socket like a radial just with two 2.5mm T+E wouldn't that be like an ideal ring in the way that current flowed down it? load would have to be perfectly balanced between each cable?

it would actually even be allowed i think but it would count as a radial wired with doubled up cable rather than a ring.

 

[trevw]

okay, thanks, that clears it up bad from a testing point of view and bad from a future extension point of view unless treated as a radial in which case why not just up the cable size I guess