Loft conversion help?

[Electrician1972]

Looking at wiring a loft conversion , it’s a large loft and there will be a bathroom a bedroom and a walk in wardrobe , The sockets are wired from the loft but are in conduit to a junction box (have only located one junction box just now) I plan on taking my cables for sockets and lights to the main DB to be on there own circuits instead of tapping into any new ones , there will be 8 sockets and a some downlights , there are no spare circuit breakers in the main DB I am wondering can I use an existing mcb for say the upstairs sockets for my socket circit and make mine a radial circuit to have more space in the MCB and the Lights into the upstairs lights MCB as there will only be two switches to go to in the loft doing loop in at switches method . Any other ideas would be helpful but if I need to will just have to change Main DB to gain space for new circuits

 

[buzzlightyear]

Separate circuits for the loft from the CU.

 

[pc1966]

Extending the light circuit up a floor is not such a big deal as low load, etc.

Doubling up the sockets MCB is a bit nasty and not any of the recognised ways of doing it. If a CU change really is out of the question then I would say least-worst is to make the new sockets part of the existing upper floor ring final so it all measures end-end correctly, etc.

How old is the existing CU? Is it all OK for satisfactory EICR, etc, as it stands?

 

[telectrix]

can you not freeupawayor 2. e.g. by taking smokes off their own circuit and dabbing in with lights?

 

[pc1966]

What is the current CU size & layout? As @telectrix says it might be that some rearrangement of what else is in there would be far more satisfactory than doubling up on an existing sockets MCB.

 

[buzzlightyear]

there will be 8 sockets and a some downlights , there are no spare circuit breakers in the main DB I am wondering can I use an existing mcb for say the upstairs sockets for my socket

Not enough space new CU needed.

 

[telectrix]

buzz'ss ££££ eyeballs lit uplike Roger Rabbit.

 

[buzzlightyear]

It makes me laugh when can I do or not do, has Haugh green youresd to say make you mind up time. Me best not to get the agro new circuits or face a firing squad.

 

[telectrix]

It makes me laugh when can I do or not do, has Haugh green youresd to say make you mind up time. Me best not to get the agro new circuits or face a firing squad.

see youse back on form then. ?

 

[Electrician1972]

Extending the light circuit up a floor is not such a big deal as low load, etc.

Doubling up the sockets MCB is a bit nasty and not any of the recognised ways of doing it. If a CU change really is out of the question then I would say least-worst is to make the new sockets part of the existing upper floor ring final so it all measures end-end correctly, etc.

How old is the existing CU? Is it all OK for satisfactory EICR, etc, as it stands?

Yes all satisfactory as is just now , would running a cable from one of the socket MCBs to a fused spur say fit that beside CU then wire my sockets on a radial from the fused spur ?

 

[Mike Johnson]

My suggestion would be to run a 10/6mm into the loft and put in its own CU for the circuits off a decent size RCB/RCBO in the original CU.

 

[Vortigern]

you say bathroom are they having an electric shower in it?
If so split tails and extra box on the side from henleys.

 

[westward10]

Sounds like you are spending a few £s on this so a new consumer unit isn't surely going to tip the scales.

 

[telectrix]

Sounds like you are spending a few £s on this so a new consumer unit isn't surely going to tip the scales.

but not an easy one to show off to the neighbours, like look at this new bathroom,all these scintillating tiles , chrome shower head, and an auto flush bog. btw, here's my new CU stuck on the wall above the bog.

 

[Electrician1972]

My suggestion would be to run a 10/6mm into the loft and put in its own CU for the circuits off a decent size RCB/RCBO in the original CU.

Could I take a 10mm twin and earth from a 32A mcb to a new Sub CU with RCB protection at the Sub CU

 

[DPG]

Could I take a 10mm twin and earth from a 32A mcb to a new Sub CU with RCB protection at the Sub CU

But the twin and would need RCD protection?

 

[telectrix]

But the twin and would need RCD protection?

not if it's surface, e.g. inside airing cupboard, or trtunking upin a corner. ???

 

[DPG]

not if it's surface, e.g. inside airing cupboard, or trtunking upin a corner. ???

Well true. But I imagine at some point it will be buried. I wouldn't be happy with a loft conversion if the submain ran up the corner of the bedroom on trunking.

 

[telectrix]

Well true. But I imagine at some point it will be buried. I wouldn't be happy with a loft conversion if the submain ran up the corner of the bedroom on trunking.

why not? i frequently excercise by running up the bedroom wall. usually after 'er indoors has had new ideas.

 

[pc1966]

I guess the point is you can have T&E without RCD protection so long as it is not hidden < 50mm from a surface.

Feeding a CU off a 32A MCB works, but is not terribly good either as any big fault is likely to trip both the CU and the feed MCB, but again depending on what is needed that may or may not be a concern. Certainly I would be looking at a couple of RCBO in such a 2nd CU to reduce the chance of something on the sockets also taking out the lights.

But what is lacking here is the design aspect - what sort of load(s) are expected, etc. If it is just lights & sockets then a 32A feed is plenty, but if there is going to be an electric showed that suddenly looks small.