Spur from a lolipop...?

[dhutch]

In past thread it transpired I have what is called lollipop, a lenght of 6mm terminated into a junction box, from which two peices of 2.5mm make a ring main.

On top of this, from the same juntion, there is a third peice of 2.5mm which feeds a swiths fcu for the boiler which is in a cupboard next to said junction.

I would like to add a light to said cupboard, and am considering adding a further spur off the main junction to another fcu to power the light.

I cant see how this is dangerous, as the 6mm is protected by the 32amp mcb, and the ring is uneffected, but I wanted other opinions on the subject.


Daniel

 

[PrenticeBoyofDerry]

Is the existing extension a ring final, with multi points being supplied via two legs of 2.5mm or is it a circuit were the cable is doubled up 2x2.5mm to each point without returning, so in reality a radial circuit?
Either way sounds like a hash up to me and I would consider corrective measures.

 

[dhutch]

Its a ring.

The 6mm is presumed to be an existing feed previously for a electric shower, given the room in question was the bathroom before it was moved upstairs.

The 2.5mm then runs out together, before spliting and running as a ring around the perimeter of the conservatory with a number of sockets on it, including a fused spur off one of them to the conservatory light.

Quite clearly the whole thing is more than a bit of a hash up, and I would much rather see the ring going back to the consumer unit as two lenghts of 2.5 as you would expect from a ring. And the lights on a dedicated lighting circuit.

However, given the diffculty in retrospectively getting the preposed cables through two rooms of the house and back to the consumer unit, as the current set up works and as far as im concerned is safe, I do not intend to replace it.

The consumer unit is a modern '17th ed' board fitting two years ago as part of the conditions of sale when I bought the house, which included a EICR.

The house was origanally rewired in the early 80s under council ownership. The bathroom being moved and the conservatory being built as far a I know at the same time, with the latter being externally glassed and being clearly atleast ten years old. All is in old colour wiring.

 

[PrenticeBoyofDerry]

I personally would have extend from the 6mm to form a radial circuit rather than a lollipop ring.
So you already have a cable that is spurred for the boiler then down fused two 3A?
Is it possible to tap in to the sorry meant supply side of this FCU, for lighting in this area, then down fuse to connect light.

 

[ericmark]

The same applies to taking multiple spurs from a socket. In theory there is no difference in fitting a double socket with two independent spurs to fitting two single sockets right next to each other wired as part of the ring and taking a spur from each. But the former is not permitted and the latter is.

What it is really down to is the number of wires going into a terminal. Most sockets are rated by the manufacturer as being able to take three 2.5 mm sq cables to each terminal.

I am uncertain as to if your lollipop method is permitted as the British ring has to follow set rules to come under the agreed system. Once you don't comply with these rules it becomes parallel conductors of unequal lengths rather than a final ring circuit.

I would not be too worried but much would depend on how the branch was made. Using a double cooker connection unit one could split a 6 mm sq cable into two 2.5 mm sq cables with only one cable to each terminal but really it should be a mini consumer unit.

The point is the home is for "Ordinary Persons" and as such we have to use type tested equipment. In a factory likely the lollipop method would be permitted as it's under the care of a "Skilled" or "Competent" person but in the home I would not be happy with the arrangement.

 

[OwainDIYer]

Can you go from the load side of the boiler FCU?

Or do you need the light on while the boiler is isolated? In which case spur from the supply side of the boiler FCU to an adjacent switched FCU for the light. Both FCUs should be fused at 3A.

That would be a non-standard unfused spur-from-a-spur but given the nature of the loads in this case there should be no risk of overloading.

Do not do this if there is any possibility of an immersion heater being used on the circuit.

 

[dhutch]

I personally would have extend from the 6mm to form a radial circuit rather than a lollipop ring.

Yes, and that would be another nicer way of doing it, but again, even that would be a lot of work as its all behind plaster.

Can you go from the load side of the boiler FCU?

The boiler FCU is down the wall, where the main junction for the lolipop is at the top ajoining the ceiling space. However I could move the boiler FCU to the top of the wall with a flex outlet at the bottom.

I could then include this fcu into the ring main, along side a second fcu for the light. Which might be neater. There would then just be the ring main joining the 6mm, with the two fcu's included into the ring.


Daniel

 

[JohnW2]

In past thread it transpired I have what is called lollipop, a lenght of 6mm terminated into a junction box, from which two peices of 2.5mm make a ring main. On top of this, from the same juntion, there is a third peice of 2.5mm which feeds a swiths fcu for the boiler which is in a cupboard next to said junction. I would like to add a light to said cupboard, and am considering adding a further spur off the main junction to another fcu to power the light. I cant see how this is dangerous, as the 6mm is protected by the 32amp mcb, and the ring is uneffected, but I wanted other opinions on the subject.

Give or take the obvious caveats about this not being the most desirable bit of design, I agree with you that I can't see any real problem (electrically) with what you are proposing.

However, what about the practicalities? What is this JB? It appears that you already have one 6mm² and three 2.5mm² cables connected to it - is there the physical capacity for yet another cable?

Kind Regards, John

 

[dhutch]

However, what about the practicalities? What is this JB? It appears that you already have one 6mm² and three 2.5mm² cables connected to it - is there the physical capacity for yet another cable?

Its currently a three pole 40amp round junction box, although the lit is cracked, so I plan to replace it. I would like to make the connection within a flush mounted push in plasterboard pattress, athough as you say, its not looking great by the time you have 1*6 and 4*2.5 coming together.

Im leaning towards moving the fcu up to the top of the wall alongside and bringing it into a ring.


Daniel

 

[PrenticeBoyofDerry]

What sort of load is on this circuit?
Would it be possible to remove the return leg of the lollipop ring and convert the circuit in to a radial by then replacing 32A device with 20A device.
Remove the spur from junction and use the return leg for boiler and light?
That would then resolve the lollipop set up and be more in line with BS7671, providing disconnection times can be met!

 

[dhutch]

What sort of load is on this circuit?

Washing machine and Tumble drier, as well as being the nearest socket to the garden, aka, whatever you wish to dream up! Welder?


Daniel

 

[PrenticeBoyofDerry]

whatever you wish to dream up! Welder?

In my dreams I have not yet been chased by a welder. (either the equipment or the operator!)

 

[ban-all-sheds]

In a factory likely the lollipop method would be permitted as it's under the care of a "Skilled" or "Competent" person but in the home I would not be happy with the arrangement.

OK.

What if (and this is hypothetical, but I can envisage such a device) a manufacturer brought out a CU with a completely different design, and a different way of connecting MCBs, having them plug into sockets on a backplane which brought the connections out to a cable management area at the top of the unit where there was more space. So from each MCB there would be an internal track/busbar running to a terminal.

Would ring finals still be allowed?

 

[dhutch]

OK.

What if (and this is hypothetical, but I can envisage such a device) a manufacturer brought out a CU with a completely different design, and a different way of connecting MCBs, having them plug into sockets on a backplane which brought the connections out to a cable management area at the top of the unit where there was more space. So from each MCB there would be an internal track/busbar running to a terminal.

Would ring finals still be allowed?

Not sure what your getting at, or how this is worse than what we currently do, assuming both ends of the ring are wired to the same 'plug in mcb' and cannot be separated without using tools.

Your hardly talking about a string of fairy lights with a plug at each end...



Daniel

 

[JohnW2]

Not sure what your getting at, or how this is worse than what we currently do, assuming both ends of the ring are wired to the same 'plug in mcb' and cannot be separated without using tools.

I think he is suggesting that a small (hypothetical) change in the design of CUs could result in all ring final circuits technically becoming lollipops, since there would be a single feed from the MCB before it got to the cable terminals, and hence split into the two arms of the ring. I presume his implication is that ring finals might well still be accepted by the regs with such a CU, and hence that 'lollipops' are really not that different from rings.

In fact, if he had wanted to split hairs, he could have gone a bit further. Even with present day CUs, there is a short 'single' path between the MCB mechanism and the L terminal where it splits into two arms of the ring, whilst the N will be fed by a 'single conductor' (from RCD or Main Switch) before splitting into two arms of the ring at the neutral bar. Hence, it could even be argued that, electrically speaking, all ring final circuits today have an element of 'lollipop' about them!

Kind Regards, John