Rewiring

[chickoo]

Hello, i recently bought a flat (run down) alongwith other renovation, it needs complete rewiring. I have worked with electrical wiring and appliances (not wiring a flat) so i am comfortable with this. I have made a list of the circuits which are below ...
New Consumer Unit (8 way)
1 Light Circuit (for 5 lights)
3 Ring Circuits (2 for each bedroom and 1 for kitchen and lounge)
2 Radial Circuit (1 for cooker and 1 for fridge)
1 Radial Circuit (Bathroom)

- Total double sockets in the 3 rings - 12
- Cooker Radial Circuit - oven, hood and hob (haven't purchased them yet so dnt know the rating yet, but there is aleady a cooker circuit with 30A fuse)
- Bathroom circuit - light and fan cord switch

I have been reading some replies by people who are have knowledge and experience, please can somebody help me with these ...

1. are the circuits appropriate ?
2. what are the circuit wise wire size ?
3. with no power shower and anything else in bathroom, do i really need to have a separete circuit like above or can i merge it with one of the rings ?
4. is cooker circuit (shown below ok) ?

CU ====>cooker control unit ====> cooker connection unit ===> hob

cooker control unit----> fused spur----> double socket----> oven and hood

 

[plugwash]

in principle your cooker cuircuit looks ok

but between the cooker control unit and the fcu you must stay in the same cable as the cooker cuircuit

also a 32A cuircuit would prbablly not run most seperate combinations without the application of diversity (which in cooker cuircuits there can be problems with due to the fact cookers do sometimes get used with everything on)

personally i would keep the existing cooker cuircuit for the oven and hood and put in a second cuircuit for the hob (and i would use 10mm cable for this incase someone wanted a big single unit cooker in future even though initially it would be on a 16A mcb)

 

[plugwash]

oh sorry didn't notice you were rewiring (my bad)

if you are rewireing i would put in just one 10mm cooker cuircuit

after the cooker control unit i would lead it into a 2 way CU like http://www.tlc-direct.co.uk/Products/CMP2N.html hidden in a cupboard

in there i would fit an appropriate breaker for the hob and a 16A breaker for the oven and hob

 

[ban-all-sheds]

1. are the circuits appropriate ?

I wouldn't have thought you needed a ring for each bedroom, unless you had a particular reason to want to isolate them individually. And I wouldn't share the kitchen ring with anything.

2. what are the circuit wise wire size ?

It worries me that you're planning a complete rewire with so little experience that you don't know this....

3. with no power shower and anything else in bathroom, do i really need to have a separete circuit like above or can i merge it with one of the rings ?

Not needed. No immersion heater? No possibility that you might put in an electric shower?

4. is cooker circuit (shown below ok) ?

I see that plug has espoused his pet theory of a mini CU. Personally I'd run a 10mm cooker circuit for the hob and a separate 2.5 or 4mm one (depending on distance and installation method) for the oven.

Other comments.

I take it that as it's a flat it's not a TT supply. Is it on the ground floor? do you need RCD protection for anything?

The CU should have spare ways for future expansion, e.g. shower.

Fire alarms?

Burglar alarm?

Don't forget that building regs will apply to you re the height of sockets and switches, and possibly low-energy lighting.

 

[chickoo]

Thanks plug and ban for your help. Actually i had tested the existing wiring for the cable age and condition and the light circuit is only 2 years (and it has its own earth too) old and i will not be adding any new light positions so i will be keeping the light circuit as it is.

As i had to take out most of the floor boards for the woodworm treatment, i could access most of the wiring.

Some additions to my earlier post ...

1. yes its a second floor flat and has its CU inside. (you may see it here

, the cooker fuse is separete

2. As a new CU is being put, i designed separete circuits for each bedroom. However you are right, there is no need to do that. I may as well combine the two rings for the two bedrooms (total 5 double sockets)

3. As its a second floor flat, i don't think it needs RCD

4. Based on your suggesstions here are the new circuits (including some appliance which i didn't add in my last post)

Kitchen

1 ring - 3 double sockets + fridge + washing machine (32A MCB) (2.5mm)
1 cooker circuit - hob + (FCU) + oven + hood (40A MCB) (6mm)

Lounge and 2 bedrooms
1 ring - 9 double sockets (32A MCB) (2.5mm)

Whole flat
1 light circuit (6A MCB) (1.5 mm)

This means an 8 way is sufficient for any future expansion (I had unnecessary rings in my last design).[/img]

 

[securespark]

Strange thinking. Second floor flat, no need for rcd. Safety not an issue then?

If no split-load board, why put the fridge on its own then?

 

[plugwash]

rcd protection is required for scokets that can feasibbly supply equipment outdoors

in a normal house this is taken to be all accessible downstairs sockets by most sparkys

in a flat it really depends on such factors as whether you have a garden and what your access is like

this is one of those regs that is hugely open to interpretation

 

[ban-all-sheds]

Strange thinking. Second floor flat, no need for rcd. Safety not an issue then?

Who's going to be supplying equipment outdoors from a 2nd floor flat?

 

[supersparks]

Strange thinking. Second floor flat, no need for rcd. Safety not an issue then?

Who's going to be supplying equipment outdoors from a 2nd floor flat?

i cant beleve that you both cant see further than the regulation definition of the use and selection of an rcd.
i would have expected better.
i fit RCDs on all boards, being a first floor flat, detached house, or 20th floor flat.
protection at 30mA should NOT be dismissed, the price difference is NOT an excuse to not have it- for the sake of 30 quid?
30mA might mean the difference between your heart beating momenterily faster, or stopping altogether.

and dont forget that you MUST fit a smoke alarm as of 1991 building regulations on a renovation which must not be on an RCD exept in a TT instalation- in whichcase the rcd should NOT be lower than 100mA

 

[plugwash]

some sparks don't put them on the upper floor sockets in normal houses because of neusense tripping

i would think if you had a second floor flat especially if it had external stairs and you had an area of garden it would be quite common to run an extention lead out for the lawnmower etc though

 

[securespark]

Exactly, supersparks.

That is why I wrote "Safety not an issue, then?"

I too am a great fan of RCD's, fitting some form of protection (either S/L or RCBO's) to every rewire or CU replacement I do, and recommending them in all other instances.

And I also was a bit confused as the poster said the fridge was to be wired on a radial. If not for the fitting of RCD-protection, then why?

 

[plugwash]

having the fridge/freezer seperate means you can easilly isolate everything except them at the CU (by siwtching off breakers) if you are going to be away for a while

 

[securespark]

Yes, I can see that, but it is normally done to exclude the circuit from RCD-protection.

 

[plugwash]

if you don't want rcd then there is no point in replaceing the board

and even if you do you could use seperate rcds for the rings

that board is a wylex standard and you can get plug in mcbs to fit them (TLC and screwfix both sell them)

 

[supersparks]

some sparks don't put them on the upper floor sockets in normal houses because of neusense tripping

thats not usualy the reason, its usualy because that is the one High load circuit they can, by regs, not put on the RCD if they needed that way for say, a radial that supplys a downstairs socket.
i always fit all socket circuits to an rcd.
tripping problems shouldent even be an excuse.
if its a rewire there shouldent be a problem with your new wiring, a properly designed system wont trip- mine hasnt tripped once in....i cant even remember
other than when work has been carrid out on the system that has tripped it via N-E shorts.

You Dont actuly have to fit an rcd on a shower circuit....
so what will go first? your body of a 50amp breaker?
for gods sake, look beyond the regs and use common sence.
im a fan of RCDs aswell.
they can be a pain in the arse when changing boards- but they are doing their job by tripping- would you prefer that they dident trip and just sat their thinking 'i wont bother tripping, its not someone getting fryed by the cooker circuit, its just that dodget fridge again'


although, if that happened i suppose you could say the cooker circuit was also doing its job by 'cooking'

like i say- rcds arnt expensive
and i fit them i dont care if its a skyscraper top floor flat or not.
its called looking beyond the regs and using common sence.

i dont fit lights on an rcd(unless TT) because i see the problem of not being able to see your way to the consumer unit as more of a hazard than somone deciding to connect their lawn mower to it.

the supply (now that i can see the picture) looks to be TN-S.