Wires into MCB - how many?

[diy_dude]

Each of my 6A MCB breakers in my CU have two live wires (1.5mm2) cabled into them:

Upstairs: Lights and Smoke alarms
Downstairs: Lights and outside lights.

I want to have a door bell transformer installed, cable installs and available space mean the transformer will be installed about 20cm from CU.

Question is: Is it OK to add a third wire to one of the MCBs or is this a bad thing?

The other 6A breakers I have are for the intruder alarm and central heating. I have no spare ways in my CU.

Thanks

 

[securespark]

Looks like you need an upgrade.

Can you post a pic?

 

[diy_dude]

Will try a pic later.

Current CU is a SquareD split board, layout is:

RCD side
32A - Kitchen sockets
32A - Downstairs sockets
32A - Upstairs sockets
40A - Shower

Non-RCD side
6A - Intruder alarm
6A - central heating
6A - upstairs lights (inc smoke alarms)
6A - downstairs lights (ins outside lights)
32A - shed
32A - cooker

 

[JohnD]

The other 6A breakers I have are for the intruder alarm and central heating. I have no spare ways in my CU.

The Central Heating and the doorbell could both be supplied from FCUs on the socket circuit. That would free up one space, and save you having to re-use it.

The intruder alarm is best supplied from the non-RCD side, so it is better not to have it on the socket circuit, so best not move that one to an FCU.

 

[diy_dude]

thanks for the input... but is it bad to physically have 2/3 1.5mm2 cables wired into the same MCB?

 

[Spark123]

Not really, there is normally more than enough capacity to get 3 lots of 1.5mm² wires into a Square D MCB.

 

[securespark]

I can get at least 16 1mm² conductors in my hager breaker terminal...

Just to prove it... with tons of space to spare!

Now, what's 16 x 14A.....??

 

[RF Lighting]

Shouldn't the blues and yellows be sleeved red

 

[securespark]

Don't look at the naked cpc's, then.....

 

[bernardgreen]

Quite a bit of exposed copper as well.

Can't get the quality these days.......

 

[Lectrician]

Absolutely NO problem with putting the additional 1mm into the downstairs MCB - 3 x 1 mm's in an MCB is fine. No problem.

 

[plugwash]

Now, what's 16 x 14A.....??

224A but that doesn't count grouping factors.

anyway a few cables in a breaker terminal really shouldn't be a problem, one you go to more than about 4 i'd worry about the possibility of some of them popping out though.

 

[securespark]

Quite a bit of exposed copper as well.

Can't get the quality these days.......

Bl**dy h*ll! I ran downstairs, threw it together in 5 minutes, photo'd it, ran upstairs, photoshopped the image, downloaded it to photobucket, then posted it as an edit onto my post, all in the space of a few minutes.....

And you're worried about the exposed conductors!

There's no pleasing some...

 

[RF Lighting]

What are you doing with old coloured cable anyway?

Is this for those non notified 'private' jobs

 

[ricicle]

I feel another challenge coming on.....How many singles down a short piece of conduit according to OSG.I've tried this one at work and believe me it's hard to comprehend!!!!!!!!!!!!