Diversity over the top???

[eyeball]

Hi there, I'm new to this forum and I'm having a go at domestic electrical work. I have just started a re wire on a freinds house and i could do with a few questions answered please.
Basically its a terrace 3 bedroom property.
It has a small cellar with a fridge and a boiler and a couple of sockets.
Ground floor there's the kitchen only a simple lay out with an electric oven gas hob, fridge, washing machine and about 4 double socket outlets. Also the living room which is only simple with 4 double socket oulets.
1st floor 2 bedrooms and 1 bathroom. There are aonly about 6 double socket on this level and the shower is not electrically heated but has a pump to pressure the water.
2nd floor 1 bedroom and a computer room. There's only 5 double sockets on this level.
The house is not crammed with all the electrical gadgets and lighting is basic on all levels. I'm putting interlinked alarms on 3 floors and thats about the scale of it.
NOW regarding the consumer unit...He wants me to have a seperate ciruit bracker for lights and sockets on all levels and separate kitchen sockets...So that's....
5x 32amp sockets
4x 5amp lighting
1x 5amp smoke....or should I piggy back one of the lighting circuits???
1x heating system but I'm not sure if it's immersion yet but lets imagine it is????
So based on that and cosidering there not alot being used sockets wise and light wise how should I work out the maximum demand and divesity?? The main incoming is 100amp would I be ok???
This may sound easy for you guys but i'm a newby to domestic wiring and I dont want to mess things up. I've looked at the OSG but reading tables is not as clear as hearing it from out in the field??
I hope you can help!!
Cheers,
P

 

[scotsparky]

i am guessing a 3kw immerser but may be a Gas combi boiler.

Its important to find out as its a fair bit of power difference.

 

[eyeball]

I know it's deff not a combi, so it could be a thirsty one. So if its a high amp jobbie, what am I looking at, at worst???

 

[Spudnik]

Hi eyeball and welcome to the forums.

No offence, but do you feel confident enough to rewire a house as your first job?

There are LOADS of things to consider even before you start, cable routes, calcs, diversity (of which you enquired), bonding, smokes etc etc.

This work would also need notifying to your LABC who will make sure it complies with the regs etc, which have had sufficient changes in the 17th edition.

 

[Guest123]

In addition to what you have, I added a 32A cooker circuit and a 16A circuit for an immersion. Ball park would be about 90A.

 

[eyeball]

Hi JasonS, thanks for the welcome and I'm sure I'll be using you alot from now on. To be honest I may have bitten off alot and to be honest I feel pretty confident. I have got the qualifications ie nvq level 3, 17th edition, 2392 but this has all been classroom enviroment and theory based more than practical. IMy problem is experience as I've never worked along side a domesric spark and so have never been able to ask questions along the way. I have registered with ELECSA to become part P registered and they will want to assess me at some point soon???? They said I could use this re wire as a assessment??? I may have bitten off alot and this is why i've joined this forum as a point to ask these questions.
With regards the diversity, I wasn't sure if having so many breakers would throw the max demand out as in reality this house could simply have a basic consumer unit with minimum breakers maybe 2x lights and 3x socket outlets but he wants all levels indepenantly fed. is this an issue??
Thanks Lennythellon, it looks as though I might be ok then.
Could you give me the breakdown on how you came to this figure, is there a simle rule of thumb other that the OSG??
Cheers,
P

 

[sparks1234]

I think its quite scary that you are considering doing this with help from a forum, it surely would make good sense to employ an electrician with domestic experience to guide you through the installation.

 

[TUX]

hi eyeball

There is no way you need five 32amp rings in that size property. i would split it into three, 1 for the celar,one for the ground fl and one for the 1st fl and the 2nd floor,4 x lighting circuits, you can not pigy back the fire alarm off of any other circuit it has to be on its own mcb,1x 16amp imersion, boiler on sw fused spur on one of the rings, 1 x 32amp for cooker, 100amp is fine for most domestic propertys this size, it is not often cost efective to go over 100amps single phase incoming supply.

regards tux

 

[sparks1234]

hi eyeball

There is no way you need five 32amp rings in that size property. i would split it into three, 1 for the celar,one for the ground fl and one for the 1st fl and the 2nd floor,4 x lighting circuits, you can not pigy back the fire alarm off of any other circuit it has to be on its own mcb,1x 16amp imersion, boiler on sw fused spur on one of the rings, 1 x 32amp for cooker, 100amp is fine for most domestic propertys this size, it is not often cost efective to go over 100amps single phase incoming supply.

regards tux

Not sure too many people will agree with the statement on the not putting the fire detection on a lighting circuit, general concensus seems to be thats the best way forward as you then know if the circuit is still on

 

[eyeball]

Hi tux, Thanks for the advice. Yes I thought it was over kill as well but it was his preferance and it is possible todo but I might advise him again tomorrow. I would prefer to keep things simple. With regards to the smoke alarms, it was going to give it its own supply but I thought Id read somewhere that people were taking a feed from the lighting circuits, this is why i'm asking you those questions. I will always work to the book but if I hear or read anything different, then I'm always curious. Sparks1234, please dont worry, I dont just do what other people say or do, like I said I will follow the book but I know there are always other options and is quess thats why there guidance notes. There is alot of very usefull information to extracted from this forum and I so far it has proofed this. I have a friend that is a domestic spark with alot of experience but I'm not able to work with him as he works for a company and for obvious reasons I'm not allowed on site but i will get him to give it the once over before I give it the big switch on.
Cheers,
P

 

[sparks1234]

Good stuff eyeball and good luck

 

[TUX]

sparks1234 yes i see where that would make sense but was told had to be on seperate circuit when i done the 17th ,is that what most sparks are doing with smokes ??

regards tux

 

[brasspark1]

Yes Tux, thats what i was told on my 17th as well. No more spuring of lighting circuits.

 

[irishsailor]

I went to an Electrical Safety Council Briefing last week and there recommendations were to Smokes in to a lighting circiut.

Irish

 

[flukey]

I went to an Electrical Safety Council Briefing last week and there recommendations were to Smokes in to a lighting circiut.

Irish

i was taught separate circuit or a regularly used lighting circuit on my 17th. only stipulation was interconnections

 

[holte end74]

hi there ive been reading with interest, pages 65&66 of the OSG explains wiring of fire detectors and alarms its states that where all circuits are protected by RCDs there is a advantage in supplying fire detectors from regulary used lighting circuits.It also states there should be a means of isolating the supplyto the alarms without affecting the lighting. how can this be achieved?

 

[wigan]

Hi Holte end74

On some units the base of the detector is akin to a socket outlet for all intents and purpose. The detector head plugs in and you twist it, similar to a starter for a fluorescent light fitting. Thats your simple isolation, to isolate base open circuit mcb.

Regards,

Kev

 

[plug444]

i was taught separate circuit or a regularly used lighting circuit on my 17th. only stipulation was interconnections

If you install the Aico Radio link system then you have too supply the bases from the local lighting circuits!

 

[zupos40]

with reference to latest thinking on smoke detector and fire equipment read page 14 Electrical safety council mag summer 09 follow link below

Our Magazine | Electrical Safety Council