Square D Quickline 2 Consumer Unit

[Allan29]

I have a Square D Consumer Unit in an occasionally used house. There is an RCCB main switch and MCB's for each circuit. The cooker (probably due to damp in an element due to infrequent use and low heating level) causes the house to trip out on occasion. To alleviate the problem (perhaps), it has been suggested I replace the cooker MCB with an RCBO, in the hope that only the cooker trips in future. I now have a suitable compatible Square D RCBO, but...
Inside the Consumer Unit, the load Neutral is terminated at the top left hand side of the Unit, whereas it is needed at the bottom.
Is there an acceptable way to detach the Neutral cable (6squaremm) and extend it by about 200mm so that it can be connected into the RCBO? Replacing the cooker cable into the Consumer Unit does not appeal!

Allan

 

[ColJack]

yellow through crimp and a length of cable, and of course the correct crimping tool ( the ratchet kind, NOT the cheap type with integral strippers that should be used for cars ONLY )

 

[rebuke]

What you're proposing won't help though, since presumably your RCBO will still be downstream of the RCCB main switch (assuming there isn't a separate non RCD main switch in the same unit then it has to be to have one point of isolation). Any faults that will take out the RCBO, will also take out the main switch...

Also note that in England or Wales changing the protection device on a circuit is notifiable under Part P (see the wiki for details).

 

[ColJack]

it's called discrimination..
the 30mA RCBO will trip before the 100mA main RCD...

and yes it's notifiable since you're changing the circuit protective device

 

[rebuke]

The OP hasn't stated it's a 100mA, I suspect it's more likely to be a 30mA one, also, unless it was a time delay type then if the fault was enough to trip the 100mA RCD then both could still trip (the RCBO wouldn't necessarily cut it off quick enough for the full 100mA to flow through the upstream RCD very briefly)...

 

[Allan29]

Thanks for all your replies. In answer to Rebuke's point, yes the main switch is 30mA; I did say 'hope' that the RCBO alone trips in future, but I was not assuming the alteration would be successful. However, if it was, then resetting the cooker would be much less trouble than the whole house. However, if Part P notification is required, that may not make the change worth bothering with?

Allan

 

[Spark123]

Don't bank on it - the RCBOs I have just tested for a quickline board tend to trip relatively slow at I/\n compaired to a normal RCD, somewhere around 120mS iirc. They go at a fairly quick 17mS at 5xI/\n

 

[sparkyspike]

If it's a single pole RCBO, then neutral to earth faults can still trip the main RCD, regardless of which one goes first.
The best course of action would be to replace the RCD with an isolator (unless you have a TT supply of course) and use RCBOs. Expensive though, especially with Square D. Alternatively a new split load cu will do the trick.

Or fix the cooker.

 

[Allan29]

I take your points Spark123 and Sparkyspike, the RCBO is single pole. I think my best course of action will be to see what next winter brings in terms of trips, since on our last visit to the house (heating on a lot due to cold weather) there were no trips.

Allan