Ring final & Radial circuits off one mcb ?

[davesparks]

We've been there before on this Dave my view won't change.

I don't remember that, but ok.

What definition of a circuit do you use?

 

[westward10]

I don't remember that, but ok.

What definition of a circuit do you use?

Was some time last year when I joined the forum went on for days. I read Reg 314.4 to mean two final circuits should have individual circuit protection and I won't sway from that. In the OPs case and probably nearly every situation like this a new circuit has just been tagged onto an existing circuit even if spare ways are available, to me the intention has been to create a new circuit and by connecting in this manner does not suddenly mean the two circuits now become one. To me this is just poor installation methods.

 

[Generator]

The Regs are based on the common sense application of established electrical principles (physics). That's the best place to start. Then check the regs for something you might have missed. I regard a 'circuit', when connected to a point of supply, as
any combination of cabling and equipment fed from the same point.
Firstly, all the cabling should be sized adequately for the maximum load it will carry
AND have a short circuit rating at least equal to the protective device to which it is connected. In the case of multiple loads ie sockets, a suitable diversity factor can be applied to the loading calculation. That calculated load should then not exceed the load current rating of the protective device.
Secondly, when the circuit comprises more than 1 parallel 'sub circuit', each one would need to be assessed separately for earth loop impedance, referred to the single protective device.
The circuit described sounds a bit dubious, but, could meet the regs if the above logical requirements are met.

 

[westward10]

What exactly is a parallel sub circuit.

 

[Toneyz]

May meet the regs but bad workmanship

 

[Deleted member 26818]

Oh the joys of Part P.
Options install a new circuit which has to be notified, or connect to an existing circuit, which doesn't have to be notified.
Options install new CU which has to be notified for new circuit which also has to be notified, or connect to existing circuit which doesn't have to be notified.
All comply with the Wiring Regs. and Statutory requirements, though some options are cheaper than others.

 

[Leesparkykent]

Was some time last year when I joined the forum went on for days. I read Reg 314.4 to mean two final circuits should have individual circuit protection and I won't sway from that. In the OPs case and probably nearly every situation like this a new circuit has just been tagged onto an existing circuit even if spare ways are available, to me the intention has been to create a new circuit and by connecting in this manner does not suddenly mean the two circuits now become one. To me this is just poor installation methods.

Would you class smoke detectors and lighting wired separately but on the same OCPD as "poor installation methods"?

 

[westward10]

Yes.

 

[Leesparkykent]

Yes.

comical.

 

[davesparks]

Was some time last year when I joined the forum went on for days. I read Reg 314.4 to mean two final circuits should have individual circuit protection and I won't sway from that. In the OPs case and probably nearly every situation like this a new circuit has just been tagged onto an existing circuit even if spare ways are available, to me the intention has been to create a new circuit and by connecting in this manner does not suddenly mean the two circuits now become one. To me this is just poor installation methods.

I agree that this is a dodgy job, they may as well have open end up the ring and extended it to serve the new sockets.

But what I am interested to know is how you are defining what is a circuit.

 

[Wilko]

Would you class smoke detectors and lighting wired separately but on the same OCPD as "poor installation methods"?

This doesn't phase me (plagarism, sorry) as the cables are likely to be the same size (if I did it ) and IMHO from mcb they form one radial circuit with multiple branches. But the OP's 4mm radial in bed with a 2.5mm rfc at 32A mcb just doesn't seem right to me.