multi circuits

[Geffers]

HI people, doing a CU change & there are a couple of circuits using the same mcb (for example a lighting circuit & an outside light wired into a 6a mcb & 1 x socket sharing an mcb with the central heating) As the job does not cover me doing anything but the change & as there are no spareways on the cu do i have to leave it as it is & just do the change? should i put it on the EIC? or can i suggest we uprate the mcb? Any reply would be helpful.

 

[johnboy6083]

you can spur off any part of a circuit )apart from another spur), and that includes the MCB

 

[tonys]

As long as you test all the circuits and mark up the dis-board and it corresponds with the test sheet/schedule then that's all you can do.

 

[Johnny-G]

Just out of interest, why is there no room for expansion on the new CU?

 

[terminator]

HI people, doing a CU change & there are a couple of circuits using the same mcb (for example a lighting circuit & an outside light wired into a 6a mcb & 1 x socket sharing an mcb with the central heating) As the job does not cover me doing anything but the change & as there are no spareways on the cu do i have to leave it as it is & just do the change? should i put it on the EIC? or can i suggest we uprate the mcb? Any reply would be helpful.

What rating is the mcb feeding the socket sharing with the CH and what size is the CH cable? And is it fused futher downstream? (I'm assuming the CH is drawing less than 3A)

As suggested by Johnny-G why not larger CU?

And what do you mean by - "As the job does not cover me doing anything but the change"?

 

[Mr Mike]

A lot of the "why questions here".
Why the CU change
Not enough ways in the CU- why
Job does not cover you.... why.

Geffers a little more help please.

 

[telectrix]

what happens when you find the rcd/s is tripping. if the job doesn't cover you for extra work, are you going to leave it?

 

[mattmoo1974]

WHy tony why tony why tony WHY.
i say How tony how tony how tony HOW.

 

[Geffers]

I will try to answer all "whys"
1-when i first looked at the job i assumed 2 x cables into a 32a mcb labeled downstairs sockets was a ring & in fact it turned out to be 2 x radials & the same has been done for the upstairs. thus the reason that there is not enough spare ways if i have to put each one separate on a 20amp mcb.
2-the mcb sharing with socket & ch is 20amp & it is fused at 3a further down (the ch)
3-the job is not covered to run cables & turn them into ring circuits. (carpets, flooring etc)
4- i have allowed time for fault tripping .
so although the cu was big enough originally with a spare way included - but if i have to separate each circuit it will not be.
so back to my original question can i have 2 x radials on the same circuit & if so should i change the mcb from 32a to 20a?
ps good replies so far!

 

[tonys]

Technically all circuits should be protected by individual devices and not doubled up.

 

[telectrix]

get a bigger board. at the end of the day, it's your name on the cert. better to pay for say 4 MCBs at £3 each . radial 2.5mm 20A MCB or less.