changing or swapping a MCB | on ElectriciansForums

UK changing or swapping a MCB

Post new thread

Discuss changing or swapping a MCB in the UK Electrical Forum area at ElectriciansForums.net

M

mmichael stath

Hi, I have a garden studio that is fed from the main consumer unit in the house. It is wired into a B6 MCB on a radial circuit which is fine but occasionally, if I use something that draws too much power the MCB trips. I use power tools which work fine as I only use one at a time obviously, but I have recently acquired a new Hoover which just trips the MCB when it is switched on.

There is a spare B20 MCB in the CU and I have tried to move the live from the B6 to the B20 but this just trips straight away. Would this indicate that this B20 is faulty (it's a reasonably old Steeple CU)?
I'm wondering if I would be able to just replace the B6 with a higher rating MCB?

I have attached a photo. In short I have tried moving the wiring from B6 (A) to B20 (B) with no luck. Can I just replace the B6 (A) with a higher rating MCB?

Thanks in advance.
 

Attachments

  • [ElectriciansForums.net] changing or swapping a MCB
    IMG_9063.jpg
    254.9 KB · Views: 111
Sort by date Sort by votes
If you've moved an (L) from one side of the consumer unit to the other, you need to move the corresponding neutral for that circuit to the other neutral bar in the CU! That why the RCD is tripping!
Make sure the cable you want to move is compatible with 20A protection.
 
Upvote 0 Downvote
stop stop stop!

the 6A is there to protect the CABLE just as much as the load on the end of it.
There is no point uprating the circuit breaker to allow 20A through if the cable is only rated to something like 16


The reason it is tripping after moving it over, is because the neutral of the circuit will still be connected to the right hand side neutral bar.... protected by the right hand side rcd.
The 20A is on the left hand side rcd.
 
Upvote 0 Downvote
Thank's for the reply.

Ah, right, I see that now. I'd assumed (which is a stupid thing to do, I know) that the neutrals were all connected to the same place?! I've attached another photo. The red line indicates the path of the current cable set up.

All of the cabling was in when I bought the house a couple of years ago. There is a small CU in the studio with two MCB's - one B6 for the lights and a B32 for the sockets and it is approx 10m from the house. The cable looks like 4mill.

Will prob contact an electrician.



[ElectriciansForums.net] changing or swapping a MCB
 
Last edited by a moderator:
Upvote 0 Downvote
mmichael stath said:
Will prob contact an electrician.
Click to expand...
best advice anyone can give you.


I don't mean to come across as all high and mighty, and a little preachy.... but please... put the cover back on before there's an accident...


Interesting to see those RCD's are not polarity sensitive... Normally, the L and N are marked on the same side
 
Upvote 0 Downvote
littlespark said:
best advice anyone can give you.


I don't mean to come across as all high and mighty, and a little preachy.... but please... put the cover back on before there's an accident...


Interesting to see those RCD's are not polarity sensitive... Normally, the L and N are marked on the same side
Click to expand...
No you are absolutely right. Just thought I'd take a gander first.

Don't know how old this is, 10 years maybe. The house was rented before we bought it and the landlord did his own work, apparently. I've had to fix a lot of his handiwork.
Thanks littlespark.
 
Upvote 0 Downvote
It looks a lot to me like that used to be fed from the B20, there will be a safety related reason it's moved. As others have said get someone qualified in to test and inspect the circuit. At a guess something might have been found on an EICR, like a high Zs that necessitated the move to the B6 that was perhaps already in the board as a spare, and would keep the light on in the studio. Given there's a B32 and B6 upstream, it all sounds very DIY.

This is all total guess work online and it absolutely needs a physical inspection from someone suitably qualified. I just like to speculate. It's also nice when people come back and inform what was the issue, I'm often left reading threads with no conclusion..
 
Upvote 0 Downvote
Just to throw an egg at the OP, if you change the OCPD on a circuit then an EICR is needed as well for insurance reasons as well as regs to BS 7671, popcorn ready, let me have it
 
Upvote 0 Downvote
davesparks said:
An EICR isn't required, some form of certification would be though.
Click to expand...
interesting Dave, I thought, and obviously wrongly (I will check the book) that if you change the OCPD by increasing it then the characteristics of the supply has changed an a EICR needed rather than a minor works. changing a 6 amp circuit to 20 amp cannot be minor works, I will look into that and find hopefully the reg number, if I am wrong, fair play, apologies, but I think not
 
Upvote 0 Downvote
MDJ said:
interesting Dave, I thought, and obviously wrongly (I will check the book) that if you change the OCPD by increasing it then the characteristics of the supply has changed an a EICR needed rather than a minor works. changing a 6 amp circuit to 20 amp cannot be minor works, I will look into that and find hopefully the reg number, if I am wrong, fair play, apologies, but I think not
Click to expand...

An EIC would be the most appropriate of the model forms in bs7671, a lot of certification software packages now have single circuit versions of this model form which would also be suitable.

An EICR is never used to certify work carried out, an EICR is a report on the condition of an existing installation.
 
Upvote 0 Downvote
davesparks said:
An EIC would be the most appropriate of the model forms in bs7671, a lot of certification software packages now have single circuit versions of this model form which would also be suitable.

An EICR is never used to certify work carried out, an EICR is a report on the condition of an existing installation.
Click to expand...
I meant EIC, No idea why I put EICR down, thanks for the clarification
 
Upvote 0 Downvote

Reply to changing or swapping a MCB in the UK Electrical Forum area at ElectriciansForums.net

News and Offers from Sponsors

PCBWay
  • Article
Meet PCBWay at electronica A1.163
Join us at electronica 2024 in Munich! Since 1964, electronica has been the premier event for technology enthusiasts and industry professionals...
    • Like
Replies
0
Views
315
PCBWay
PCBWay
Electrical2go
  • Sticky
  • Article
📢 Best Sellers Catalogue Now Available! 📢
Good to know thanks, one can never have enough places to source parts from!
Replies
4
Views
841
Bob Labla
B
Dan
  • Article
The Official Sponsors of ElectriciansForums - There are currently 8
OFFICIAL SPONSORS These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then...
Replies
0
Views
954
Dan
Dan

Similar threads

S
  • Question
Consumer unit MCB selection
What is the distance from the point outside the house to the shed?
Replies
8
Views
777
KungFuTurkeyLeg
KungFuTurkeyLeg
MaintenanceSpark
Day 2 Thread 2 - Soviet Union Electrics
The MCBs are branded Noark.
    • Like
Replies
5
Views
373
freddo
freddo

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by untold.media Operating under the name Untold Media since 2001.
Back
Top