Electrical spur extension

[Stefanplant]

Is it OK to run a spur straight from the consumer unit by connecting the wiring to an already used fuse in the comsumer unit.

I know I can run a spur from any socket but can I run a spur from an already used connection in the consumer unit?

Thanks,

Stefan.

 

[cozycats]

Yes you can as long as you connect it to a suitable fuse/breaker, not a dedicated circuit for shower/cooker etc. This will be notifiable to lbc as adding new circuit.

 

[tekkiesteve]

No!
Where an installation comprises more than one final circuit,each final circuit shall be connected to a separate way in a distribution board.
The wiring of each final circuit shall be electrically seperate from that
of every other final circuit, so as to prevent the indirect energising
of a final circuit intended to be isolated.
Therefore each socket is considered as a final circuit and doesn't
comply to BS7671.

Steve

 

[JohnD]

Therefore each socket is considered as a final circuit and doesn't
comply to BS7671.

 

[JohnD]

(it's a spur)

 

[tekkiesteve]

reg 314-01-04

Its two individual circuits!

 

[securespark]

reg 314-01-04

Its two individual circuits!

Steve

If it is a spur off a ring final, then yes, you can come off the same terminals in the CU as the ring does.

The OSG mentions three points on a circuit where a spur can be wired to: a socket outlet, a junction box or the origin of the circuit in the CU.

OSG, p153.....

 

[cozycats]

Interpretation!!! Personally I understand the reg to mean that any circuit must only have one point of disconnection (Fuse/mcb etc), and NOT.... as I've often come across a ring with a 15 a fuse at each end, ie TWO points of disconnection

 

[securespark]

Nomenclature:

A "spur" is an outlet fed off a ring final with just one cable supplying it.

If it is a socket outlet not intended to be wired from a ring final, then it is a radial circuit.

 

[tekkiesteve]

Securespark
I stand corrected if its a ring final
I know its frequently seen but not best practice.

Steve

 

[tekkiesteve]

Stefan plant
I your still following this thread and you still wish to run the new circuit from the cu from a ring final (ie 32A mcb protection) i would run it in 4mm.

Steve

 

[Spark123]

Why 4mm²?

 

[RF Lighting]

The spur will be fine in 2.5mm2. The most current that could be drawn through this cable is 26A under worst case conditions of a fully loaded twin socket, and this is not an unacceptable setup. If you were to spur off any other point of the ring would you therefore use a 4mm2 cable for this aswell? There is no technical difference between spuring from a socket, joint box or circuit breaker in the CCU.

Rob

 

[tekkiesteve]

Because 2.5mm can take 27A, i know a dso is max 26A and then an allowance for diversity can be made but;
Best practise if your "spurring at the mcb" is to assume that someone will convert it to a radial circuit in the future, so larger cable is better.

Steve

 

[securespark]

Securespark
I stand corrected if its a ring final
I know its frequently seen but not best practice.

Steve

Why do the OSG condone it, then?