Four cables on a plug socket

[Tueur]

hi guys,

I am hoping you can help me out here. I am currently redecorating our house room by room and am on to my second room now. the first one was slow but no major issues.

I am starting our main bedroom and planning on relocating some existing plug sockets. I have just taken the faceplates off to see if the installer has used trunking ant they appear to have done so which is good. There are 2 double sockets on one external wall the left socket has four cables running to it the right has 3.

I can understand 3 cables as 2 would be ring main and the 3rd could be a spur, but 4 makes no sense unless it is 2 for ring main and 2 separate spurs. The other weird thing is that I dont understand what the spurs would be. There cant be any sockets on the other side of the wall (its external), and there are no sockets on the walls downstairs. Does anyone know of any logical reason why you would have 4 cables going into a plug socket?

Thanks

 

[flyingsparks]

Sounds like as you say probably a ring and two spurs from one socket. This needs attention tho as it isn't allowed. You can only have one spur from a socket, and that socket must be on a ring. What size is the fuse/mcb protecting the circuit? If it is 20A it could be a radial circuit, and although bit of a bodge, not necessarily dangerous. Are all the cables 2.5mm?

 

[JohnW2]

Sounds like as you say probably a ring and two spurs from one socket. This needs attention tho as it isn't allowed. You can only have one spur from a socket, and that socket must be on a ring.

AFAIAA, it is only 'not allowed' if (as is likely) the terminal capacity of the socket's terminals is not (or, at least, the manufacturer claims that it is not) adequate for four conductors. I am unaware of any regulation which specifically prohibits two spurs originating at the same point on a ring - which makes some electrical sense, since there certainly is no regulation which specifically prohibits spurs originating from two sockets (or JBs) a couple of inches apart! In either case, the designer has to be satisfied that none of the circuit's cable is "likely to be overloaded for long periods", something which really only needs even thinking about if the spurs are fairly close to one end of the ring.

Kind Regards, John

 

[Tueur]

So I have spent the afternoon with a cable tracer (tone generator and probe) to work out what is connected to what and how it is wired and it is not good.

Old Current

• Tueur
• 7 Feb 2015
• 1

It appears as though the ring comes in from Bedroom B to socket BASO1 and then goes back through the wall to Bedroom B. At somepoint in the past BASO2 and BASO3 have been added and wired in a second ring! BASO2 then has a spur that goes down through the floor to a socket in the room underneath (This location is not accessible from the downstairs ring).

I believe I can fix this by crimping two ends in BASO1 so that BBSO1 is connected straight to BASO3 as below.

Old Planned

• Tueur
• 7 Feb 2015
• 1

I am planning on moving BASO1 and BASO2 so can install some new cables but I am going to need to crimp the 2 cables that go to Bedroom B. Am I right in saying that Crimped joints dont need to have access and can be under the floor boards? Also, we are planning to lay new carpet, so how reliable are crimped joints?

Thanks

 

[deadshort]

Hi, what size is the mcb?


Regards.


DS

 

[JohnW2]

Where are the two 'ends' of this part of the quasi-'ring' which go to your CU?

Kind Regards, John

 

[Tueur]

Also, Any tips for pulling new cable through suspended beam floor? Im thinking crimp new cable on to the end of the old one then pull the old cable out which will pull the new cable through?

 

[Tueur]

I believe it's 32 Amp MCB. what do you mean Qasi-ring. I havent mapped the rest of the house yet so not sure of the path back to CU

 

[JohnW2]

I believe it's 32 Amp MCB. what do you mean Qasi-ring. I havent mapped the rest of the house yet so not sure of the path back to CU

What I mean is that what you have shown us so far does not look like any sort of 'ring' - the topology might become clearer once you discover how the two feeds back to the CU connect to what you've shown us so far.

Kind Regards, John

 

[deadshort]

If you have one cable running from the CU with a 32a MCB it's a fire hazard, and does not compy with regs. I would reduce the mcb to 20a or 25a if your drawing is correct.


Regards.

DS

 

[sparkwright]

Is there any reason why, at the socket with 4 cables, it can't be modified with some connector blocks and some short bits of wire?

One leg of the ring, one spur cable, and a short length of wire could get joined in 30 amp connector blocks.

Then the other ends of the short length, the remaining leg of the ring, and the remaining spur cable gets joined to the socket.

So the joint within the back box consists of three sets of cables; and the socket itself has three sets of cables connected to it.

This would be acceptable, wouldn't it?

 

[JohnW2]

Is there any reason why, at the socket with 4 cables, it can't be modified with some connector blocks and some short bits of wire? ... One leg of the ring, one spur cable, and a short length of wire could get joined in 30 amp connector blocks. ... Then the other ends of the short length, the remaining leg of the ring, and the remaining spur cable gets joined to the socket. ... This would be acceptable, wouldn't it?

Frankly, if there are currently four conductors satisfactorily terminated into the socket terminals (which is certainly quite possible with some, like MK, regardless of what the manufacturer says), I would regard that as more satisfactory that the 'contrived' arrangement, involving additional joints, which you are suggesting. but that's obviously just a personal opinion!

However, it's looking as if the 'four conductors in one terminal' may well be the least of the OP's problems. He seems to have a circuit wired in 2.5mm² cable and protected by a 32A OPD which, in terms of what we';ve been shown/told so far, doesn't look anything like a ring.

Kind Regards, John

 

[deadshort]

Sorry, I believe its 32a ?

DS

 

[JohnW2]

Sorry, I believe its 32a ?

That is, indeed, what we were told. Why are you sorry, and what was your point?

Kind Regards, John

 

[Tueur]

Thanks for the input guys.

Deadshort - The fuse box is outside and I have hung up my tools for the night. I will check the rating tomorrow.

JohnW2 - The "actual", original ring that goes back to the CU comes in from the 2 sockets in Bedroom 2. ie the original ring was BBSO1 - BASO1 - BBSO2. BASO2 and BASO3 were added later and badley wired in from what I can tell. My fix is to break in to the original ring as per the second diagram