Replacing a Consumer Unit

[gerety]

Hi,
I have a new looking CU in my recently purchased flat. It only has 4 MCB slots, and only 2 MCBs supplying the whole 2 floor flat. The other 2 spots are taken up by a bell transformer.
I want to replace the CU, and add some circuits to make the kitchen legal.

If an electrician replaces a CU, do they have to start checking every wire in the house? or can they simply reconnect existing circuits? One guy insisted that he could not give me a certificate of works unless he ripped out all the old wiring. Seems excessive but I cannot find it written anywhere what is required by law.

Thanks for any advice

 

[rjb]

Can you add some further information.

What circuits are you wanting to add? What the existing circuits? Does your current CU have any RCD's.

Perhaps posting a picture could help.

Naturally, if a CU was replaced then the electrician would test the whole circuit to ensure they are safe. In fact any good electrician would want to test the system before making any CU. For example if you upgrade an old CU for a CU that incorporates RCD's then the RCD's can start tripping as the old CU fuses/ MCB didn't detect earth leakage, only over current.

No circuits need changing unless they are not safe. From the information you state it sound like the electrician is touting for extra business.[/u]

 

[gerety]

The existing circuits are a 5A MCB doing the lights, and a ~36A MCB doing all the sockets plus the whole kitchen(!). The kitchen is actually a spur off a socket in the study. Crazy. I would like to run new circuits to the kitchen, say one of the oven, one for the sockets, and one for the lights.

I have no RCDs on the box. I'm not clear which circuits in the house might need them, but perhaps the kitchen sockets? (ie risk of water contact?).

I'm glad to know that I don't HAVE to pull all the wires. I will obviously have everything tested by whoever does the work, and remedy problems.

Also, the guy said I have 0.6mm supplying the CU and that now I need 1.5mm. That sounds like it could be true. Does changing the CU mena I do need to get the incoming wire upto code?

Thanks

 

[Adam_151]

On RCD we have to put sockets that can be reasonably be expected to supply portable equipment used outside, heated floors, and some equipment in bathrooms (although unless the maker says so, no need to put electric shower on one...crazy!)

I'd certainly put the shower on an RCD regardless, along with all of the general purpose sockets (best ideal to try and get fridge and freezer on separate circuit off rcd for obvious reasons)

Keep cooker off the RCD, but this means you need to use a cooker control unit without a socket


1.5mm² is likely to be a misunderstanding, we use that for lights, for meter tails 25mm² is the norm these days (and 16mm², or 10mm² might be found on older installs)

EDIT: Good that you're getting someone in there may be a fair bit of remedial work, but unless its in a terrible state, then hopefully there wont be a need to rip it all out and start fresh!

 

[gerety]

I now understand more about RCDs,thanks.

My "tail" is probably 16mm not the stupid 0.6mm I wrote. So will I need to upgrade this tail to put in a new CU? The concern is destroying the communal areas of the building (old victorian) to get the new 25mm2 up....but obviously no messing around if it is the lar.

Thanks for all your help!

 

[RF Lighting]

If your CU is supplied as a submains, then you may not need to upgerade the supply cable from the switch fuse (I would guess in a communal switchroom) to your CU.

 

[JohnD]

Can you post a pic of the CU? And whatever there is downstairs near the meter or supplier's fuse?

we like pictures