Spur from 32MCB

[Ashley-Joseph]

Just wondering if I got this right but is it ok to take a 2.5mm spur from a 32MCB ring main Or should I use 4mm cable.

 

[Spoon]

Have a look at Appendix 15 of the BBB (Page 505)

 

[bill01803]

You can spur 1 double or 1 single on 2.5mm

 

[Pete999]

Have a look at Appendix 15 of the BBB (Page 505)

What Spoon said

 

[Ashley-Joseph]

Thanks

Have a look at Appendix 15 of the BBB (Page 505)

 

[Dustydazzler]

Keep it on the ring if at all possible

If not , 2.5 is fine

 

[Ashley-Joseph]

Yeah my other thoughts were to just ad a 20MCB with a 2.5mm radial for 1 socket.

 

[Pete999]

Yeah my other thoughts were to just ad a 20MCB with a 2.5mm radial for 1 socket.

Appendix 15 should ex[plain it all, a good read is required.

 

[static zap]

The 2.5mm the spur is made with has an advantage ,
it is not evolved in the current flowing thru the rest of the ring .
(that may already be well loaded)

 

[Pete999]

The 2.5mm the spur is made with has an advantage ,
it is not evolved in the current flowing thru the rest of the ring .
(that may already be well loaded)

Sorry, explain please

 

[static zap]

Sorry, explain please

(Tin hat in place)
a) Attempting to explain where common sense seems to imply --with 2x 2.5 entering a socket in RFC ,that 4mm might be more appropriate for spur wiring...
(ignoring physical constraints of the situation)
b)(or is the situation confused with spur/radial references .. -5 Skill points)

 

[Ashley-Joseph]

I think 4mm is more suited as Iz has to be higher than In.

 

[Ian1981]

I think 4mm is more suited as Iz has to be higher than In.

Your spur will not require overload protection as long as the load can not exceed the Iz of the spur cable so at most you can only have a max load of 26 amps from one double socket which is highly unlikely that that is what will be used.
2.5mm is more than adequate for a single spur

 

[Taylortwocities]

Yeah my other thoughts were to just ad a 20MCB with a 2.5mm radial for 1 socket.

You could, but that is a new circuit with the need to notify the work to the local authority. Not worth the PITA.

 

[mhar]

If you look at appendix 15 you will see that you can spur from the origin in 2.5 which will negate the need for a 20A mcb as you suggested in your post 7

 

[Bellendian]

I see plenty of EICRs stating that 'multiple circuits' are connected into 1 breaker and need rectifying. On inspection it's often just a spur taken from ring at MCB and no issue at all!

 

[Deleted member 9648]

I see plenty of EICRs stating that 'multiple circuits' are connected into 1 breaker and need rectifying. On inspection it's often just a spur taken from ring at MCB and no issue at all!

This is a common misconception, 'multiple circuits' in one MCB is an impossibility by definition. If there is one point of connection to a protective device at the source of supply it is one circuit no matter how many cables are connected.

 

[j1mbodrea]

Just wondering if I got this right but is it ok to take a 2.5mm spur from a 32MCB ring main Or should I use 4mm cable.

Suprised no one has asked what your design current will be ???