Refurbishment to flats...

Discussion in 'Electricians' Talk' started by graham3232, Mar 26, 2004.

  1. graham3232

    graham3232 New Member

    Got an exciting job coming up:-/ My mates converting an old pub into four flats 2 up and 2 down.

    Anyway I'm doing the wiring I've listed the specs below if anyone had any ideas or advice it would be appreciated because I've never wired flats before!

    40A single phase supply to 5 way consumer unit with 40A (30mA) RCD/Isolator
    32A Ring main for sockets
    6A lighting
    6A smoke alarm with battery backup (incase RCD trips)

    Supply is overhead, but leccy comopany are putting new supply and four credit meters, no details from them yet.
     
  2. plugwash

    plugwash New Member

    seems reasonable except for the smoke alarm

    i'm pretty sure they are not supposed to be on 30ma rcds not sure on the affect of battery backup as regards the regs a split load may be a good idea

    how are people in the flats going to cook gas?

    will the boards credit meters be in the flats?

    if so i would advise putting in split load cus with isolators and rcds to match the service fuse the board puts for the credit meters
     
  3. unphased

    unphased Screwfix Select

    Hi graham

    First glance doesnt look right. We need some more from you

    How many rooms per flat?
    What is the existing supply (Is it TT? You mention o/h cables)
    How many circuits per flat? (Ring main, lighting, cooker, smoke alarm, immersion heater, ch etc?

    Ta

    RSS
     
  4. splater-and-duck

    splater-and-duck New Member

    dont for get lecky shower they eat the amps these days as well. could be a git if they become an after thought.
     
  5. Tangoman

    Tangoman Well-Known Member

    I'd be pretty ****** off if I bought a flat and discovered I could only use 40A! Different for lettings though!

    Tango
     
  6. LSpark

    LSpark New Member

    dont mean to put you off, but i think you need to investiage/ find out a little more about ure instalation requirements etc, befour commecing or taking on the job, i wouldnt want you getting stuck with somthing tricky to sort out, been there in the past!
     
  7. The Trician

    The Trician New Member

    Sort out your Maximum Demand first and come back to us - 40A doesn't seem big enough unless the electric cooker is being shared by all 4 flatmates - or all cookers are gas. Also consider future-proofing - will they want showers etc fitting later on?
     
  8. LSpark

    LSpark New Member

    i dont know if this helps or not ,but i did 1 job working under some 1 else, was 2 or 3 flats, we used 35mm SWA-3core, and adaptable boxes etc, but im sure you would need to do somthing similar fot this, each meter would be inside each flat.
     
  9. motor head

    motor head New Member

    Hi the demand on the consumer unit is only 40 Amps one ring 32Amps, 6Amp Lights/ Diversity ?!!!!! Hot water 16Amps, Cooker 20Amps,(Washing) Can you not put in 60Amp Meter.As there is the problem of changing the consumer unit as it will start to trip more and more so at the end you may have to keep going to reset it or have to get the supply compony to change the servive fuse more of ten thats exspensive

    Can the supply cable be up ttt
     
  10. Rabbit Rabbit

    Rabbit Rabbit New Member

    The mention of fire alarms - installation of by sparky's - is that OK under whatever regs that may apply for fire detection? Especialy as the flats are going to be rented out there may be, I say MAY BE, some horrendous ramifications ahead, check ya Third Party Insurance as well. I am not familar with the situation and have fitted mains powered interlinked fire alarms myself but have often wondered ... what if???
     
  11. graham3232

    graham3232 New Member

    Thanks for your help so far guys, heres a bit more info for you.

    Four 2 bedroom flats, with bathroom, living room, kitchen per flat, Average room size about 3 x 4 metres.

    There will be gas heating and gas hob. Shower runs off gas combi boiler. No Immersion etc.

    oven will be electric but is only a 2KW one so will go on a FCU on ring main as will boiler.

    Smoke alarm one per flat not interlinked on 6A MCB (As specified by building control)

    Not sure of existing supply earthing, but is overhead and no more than 10 years old. Waiting to hear back from leccy company about new supplys probably 3 phase though.

    Can't see me needing more than 40A per flat ???
     
  12. unphased

    unphased Screwfix Select

    evenin graham

    Well I've done a rough and ready max demand calc for you and 40A is looking light. Her is calc

    <u>Maximum demand calculation 2 bed flat</u>
    Assumptions
    Lighting
    4 tungsten light points at 100W each 400W
    1 fluorescent light point (in kitchen) 85Wx1.8 153W

    Total 553W

    Applied diversity at 66% of total 0.66 x 553 = 365W

    Assumed current demand for lighting 365/230=1.6A
    Power
    2 ring circuits at 30A
    1 at 30A
    1 at 40% 0.4 x 30 = 12A
    1 cooker rated at 2kW 2000/230= 8.7A

    Assumed current demand for power = 50.7A
    Maximum Demand
    Total assumed max current demand 1.6 + 50.7=52.3A

    Would suggest you go for a 63A supply per flat this will have capacity to add stuff in the future and give spare.

    Regards

    RSS
     
  13. plugwash

    plugwash New Member

    cant see why a 2 bedroom flat needs two rings but putting a smoke alarm and lighting on a 30ms rcd is not considered good practice at the very least

    i would say get a 63A switch cu

    1 32A ring on a rcbo
    2 6A cuircuits for lighting and smoke alarm
    1 16A cuircuit for oven

    even if all theese were fully loaded (very unlikely) they couldn't overload the 63A main isolator
     
  14. ban-all-sheds

    ban-all-sheds New Member

    graham3232, on Mar 25, 2004 4:10 PM you wrote "Can you pro's tell me roughly how long iot takes to rewire an average family house. Including things like testing etc."

    Which makes me wonder if you are not actually a pro yourself. Apologies if I've read too much into that Q, but if you aren't qualified I don't think you should be doing work on properties which will be sold/rented out....
     
  15. sparkedout

    sparkedout New Member

    I agree any sparks knows this stuff already
     
  16. graham3232

    graham3232 New Member

    Thanks for all the advice. I'll put the oven on a 16A radial then have one ring main for the flat. I have been informed from other people on the street that all the supplies are at least 60A anyway. Flats are being sold.

    Just to clarify my position I'm not qualified, I'm helping with the design and installation. Thats like where I do it and someone NICEIC approved checks it I've wired few houses before its just that flats are a bit different so was just looking for advice, thanks!
     
  17. Rabbit Rabbit

    Rabbit Rabbit New Member

    Spot on ban<u>all</u>sheds. I agree 100% regarding properties that may be let, a highly charges and sensitive subject.
     
  18. Rabbit Rabbit

    Rabbit Rabbit New Member

    'charged' not 'charges' - a BIG difference between the two words!
     
  19. ban-all-sheds

    ban-all-sheds New Member

    Just to clarify my position I'm not qualified, I'm helping with the design and installation.

    I can't see how you would have the PLI that you need to be able to carry out work on property on this basis.


    Thats like where I do it and someone NICEIC approved checks it

    Well - maybe I'm being a bit of a Jeremiah, but I can't see a NICEIC guy putting his name to something designed and installed by an unqualified person.

    I sound like I'm really down on you - I'm not - I champion the cause of DIY-ers, but you're straying into the world of commercial property development, and I don't think you should...
     
  20. Chester

    Chester New Member

    I agree with BAS - having only just done my final exams and still feeling that I know sweet f.a. about the real world of leckies, I find it a bit frustrating & not a little worrying that we are encouraging diy'ers to take on projects that I still have to sit down & do my homework for.... I wonder if scewfix feel the site could be criticised for providing it. I've only just found it and hope to keep picking your brains for a while yet, so lets keep it bombproof eh?. Regards to all, Chester.
     

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