Two cables connected to mcb

[Jay89]

Evening All

Im sure this will have been discussed at some point (if so please point me to a relevant thread)

I have been to look at some remedial work where a previous inspector has flagged up on multiple circuits 'DBx Cx has two cables in mcb, need separating - C2'

These circuits are either lighting or radial power circuits supplying a small amount of sockets. All suitably rated and with decent R1+R2 readings.

I have never seen this to be worthy of a mention let alone a C2 code, i have spoken to my CPS technical and they said they cant see an issue. Just looking for anyone else's opinion

Thanks in advance!

 

[westward10]

I would C3 it, two final circuits require individual circuit protection.

 

[davesparks]

I would C3 it, two final circuits require individual circuit protection.

It's not two final circuits, it is one, the definition of a circuit in bs7671 is very clear on this.

What basis do you have for a C3? What is the improvement that can be made? Unless this Mcb is overloaded, which is a separate matter, then nothing is improved by splitting it in to two circuits

 

[Andy78]

I would C3 it, two final circuits require individual circuit protection.

I'm not biting

 

[westward10]

I suspect this is the case of an existing circuit and then someone lashing another to it because they cannot be be bothered to employ correct installation methods by using an additional protective device at a spare way or advising the existing board has inadequate capacity.

 

[Jay89]

I suspect this is the case of an existing circuit and then someone lashing another to it because they cannot be be bothered to employ correct installation methods by using an additional protective device at a spare way or advising the existing board has inadequate capacity.

There are multiple consumer units in this EICR where it has been flagged, from what i can see most seem to be part of original installation (same cable and paired dressing). Mostly on three phase boards with no spare ways.

 

[davesparks]

I suspect this is the case of an existing circuit and then someone lashing another to it because they cannot be be bothered to employ correct installation methods by using an additional protective device at a spare way or advising the existing board has inadequate capacity.

Based on what evidence? Whilst this is possibly what has happened, there is nothing in the regulations to prevent a circuit being extended in this way.
If a radial socket circuit has the capacity for additional sockets, then why not extend it from the DB if that's the most logical place to connect it? Surely this is better than adding an additional joint into the circuit somewhere?

 

[Jay89]

I should add it has detailed labelling at each consumer unit also

 

[westward10]

See in day in day out and I will C3 it every time.

 

[davesparks]

See in day in day out and I will C3 it every time.

And which regulation do you reference to support this observation?

 

[buzzlightyear]

I should add it has detailed labelling at each consumer unit also

was the boards marked up for the
2 circuits to the mcb.

 

[westward10]

314-01-04 off the top of my head but I suspect you know this.

 

[Jay89]

was the boards marked up for the
2 circuits to the mcb.

All points supplied by that MCB yes

 

[davesparks]

314-01-04 off the top of my head but I suspect you know this.

I can't see anything in 314 to support your opinion, the closest thing is that each final circuit be connected to a separate way in a DB. There is nothing to say that a final circuit cannot comprise multiple branches from one ocpd.

 

[buzzlightyear]

reg 314.4
when an installation comprise more then one final circuit .each final circuit shall be connected to a separate way in the distribution board .

 

[davesparks]

reg 314.4
when an installation comprise more then one final circuit .each final circuit shall be connected to a separate way in the distribution board .

Yes, now add the definition of a circuit.

There is nothing which prevents a circuit being formed of two branches from an ocpd. This could be a better design if it reduces th overall length of the circuit