Confused please help

[wesj]

I am building a kitchen and lounge extension for a customer and have got to the 1st fix electrics stage.I would be happy to carry out this work after first informing building control but frankly do not have the time so got him to call a sparks.The electrical work consists of additions to the downstairs lighting circuit for the kitchen and lounge ,extension to a ring circuit for extra sockets in new lounge and extension to the original kitchen ring incorporating new sockets,FCUs and outlets for integrated appliances and a new 32 amp 6mm T&E radial supply to cooker switch and outlet for a 5.2KW oven.I suggested I meet the electrician so I could explain I intended to board & dab the walls and ask if he wanted any extra noggins in stud walls etc. SORRY to bore you with this long intro but now to the point.The customer about 5-6 years ago had anew consumer unit fitted a Wylex NH1104, all breakers, no RCD protection I suggested that possibly the cheapest way to have the new electrical works carried out and to conform to regs would be to replace the 32amp MCBs on the kitchen and lounge rings ( lounge has French doors so power may be taken outside) with RCBOs and use one of the 32 amp MCBs for the cooker radial.The electrician said that to part P certify, all circuits suppling socket outlets in the house would have to be RCD protected. I think this is wrong as I understand it to certify he only has to check main earthing is correct and that the circuits he is working on will take the additions and that his work is to 7671.One last thing the cooker radial is that OK to part P certify on an MCB not RCD protected.Please could qualified sparks give their comments many thanks

 

[Taylortwocities]

Theres some 'it depends' here. If your supply is TN-S or TN-CS then its only sockets that could be used to power equip outdoors. So all downstairs sockets then.
If its a TT supply then its all sockets. But there's other things to consider also for TT.

If its a recent board (5-6 years ago) it should already have an RCD for those sockets as 16th edition was in force then

If it is a recent board it could be upgraded to a split load for the cost of an RCD and an upgrade kit. That is what i would do, some others would put RCBOs in.

The cooker circuit wont need an RCD provided the control unit does not have a socket.

 

[daytona]

agree with the above mate if you wanted a second opinion.

in laymans terms you are right and the sparks is wrong.unusual to meet a builder thats clued up on electrics.
a bit of job creation perhaps?

have a look at the main incomer maybe post a photo or describe it to us and we can tell you in a second if its tt or not.what we need to know is where does the main earth go?

 

[wesj]

Thanks TTC & Daytona, I forgot to say the supply was TN S

 

[wesj]

Forgot to say in my previous reply TTC although your conversion method is certainly the best route the consumer unit has space for only 1 more RCD/RCBO and not the wider main RCD control unit, and although all sockets which could potentialy supply outside power (ground floor sockets)should be RCD protected if the electrician has protected the circuits he has worked on what in the regulations would stop him issuing part P certification? Thanks again -- Wes.

 

[daytona]

well im here so i will answer!
as long as downstairs sockets and kitchen sockets are rcd protected then he can issue the cert,providing his readings are ok obviously.


cooker does not need rcd protection as long as no socket on the switch

 

[wesj]

Thanks daytona for your diffinative answer . kind regards wes