Posting a message to the forum will remove the above advertisement

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Electrical 2 Go - Electrical Supplier and Electrical Wholesalers

    Please visit our prime electrical forum sponsor - they have the best tools at the best prices. If you find a price better somewhere else, call them or contact them, and they may be able to beat it for you. Especially on an order of a few items.

    Dismiss Notice

Discuss PME supply block of flats in the Electrical Forum area at ElectrciansForums.co.uk.

Please make sure you checkout our forum sponsors, many do discounts for members and, they keep the forum free to use.
  1. chris day
    Offline

    chris day London Sparks

    Location:
    london
    Business Name:
    Platinum electrical
    Hello Guys

    I have a 200a 3-phase supply PME bolted to a large ryefield panel, the ryefiled panel then supplies 14 flats within the same building.

    Each flat is supplied a 63a from ryefild via meters in the form of a 16mm 3core SWA cable.

    The furthest away is flat 14 at around 25 meters, seeing as we are exporting the PME supply i would need a minimum 0.05 max between the main bonding in the flats and the MET at the origin (Ryefeild) because the CPC in the SWA is a combined CPC and main bond.

    how can i calculate the R2 value alone as looking at table 11 OSG its R1+R2.. would i simply divide by two seeing as the line conductor is the same CSA.
     
  2. ChrisElectrical88
    Offline

    ChrisElectrical88 Forum Mentor

    Location:
    Norwich
    Calculate R1 R2 and divide by 2 as it is exactly the same conductor size as you suggest.
     
  3. Tony Reidy
    Offline

    Tony Reidy Regular EF Member

    Location:
    bedfordshire
    Business Name:
    T Reidy
    Do a long lead test an you will have r2
     
    • Like Like x 1
  4. cliffed
    Offline

    cliffed Regular EF Member

    Location:
    Lancs
    The resistance is not the issue here,the main bonding must be sized accordingly to the Neutral size.
     
    • Like Like x 1
  5. Strima
    Online

    Strima Electrician's Arms

    Location:
    St Neots
    Can you show me where it states maximum of 0.05 ohms for bonding?
     
    • Like Like x 1
    • Agree Agree x 1
  6. chris day
    Offline

    chris day London Sparks

    Location:
    london
    Business Name:
    Platinum electrical
    Thanks Cliffed... so your saying if i just look at table 54.8 will that be the neutral in the SWA sub mains of the neutral of the incoming main supply
     
  7. Wilko
    Offline

    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Hi - it’s the size of the incoming DNO supply at the last point where it’s still a PEN conductor, if I’ve understood correctly. Hopefully it’s 50mm or less and you’re good with the 16mm (values from Table 54.8 as you say). The 0.05 Ohms thing is an urban myth :) .
     
    • Agree Agree x 2
  8. Bellendian
    Offline

    Bellendian Regular EF Member

    Location:
    Gatwick
    Just playing devils advocate for a second, but what is it that requires main bonding in each of the individual flats?
     
    • Like Like x 1
  9. cliffed
    Offline

    cliffed Regular EF Member

    Location:
    Lancs
    Exactly,could well be 25mm,for main bonding,also Main Earth should be sized accordingly,maybe for 200 amps 35mm,good luck.
     
    • Like Like x 1
  10. mhar
    Offline

    mhar Electrician's Arms

    Location:
    devon
    The BNO should have the spec of the supply so you can determine the size of the N, if not a quick phone call to your DNO would be the way to proceed.
    Your DNO will have a policy document for their requirements for protection for multi way distribution units (Ryefields etc), ask for a copy
     
  11. bigspark17
    Offline

    bigspark17 Electrician's Arms

    Location:
    wales
    I cant see why any bonding would be required internally to the flats? Any bonding would need to come from the ryfield/MET to water/gas/structural in prefumanly cellar/switchroom. As other have said, what is dno supply/tails?
     
    • Like Like x 1
  12. chris day
    Offline

    chris day London Sparks

    Location:
    london
    Business Name:
    Platinum electrical
    DNO tails are 70mm 3- phase and neutral on a 200a bs 1361 fuse.
     
  13. chris day
    Offline

    chris day London Sparks

    Location:
    london
    Business Name:
    Platinum electrical
    The water and gas inside the flats are 10mm bonded ... the thing that I am quite confused about is the main bonds for the water and gas coming into the building is one huge 50mm cable.
    Then inside the flats 10mm water and gas bonds

    There are two main bonds?
     
  14. davesparks
    Offline

    davesparks Forum Mentor

    Location:
    guildford
    Main bonding should be installed for each installation.
    The installation in each flat is a seperate electrical installation and should have its own main bonding.
     
    • Like Like x 1
    • Agree Agree x 1
  15. Bellendian
    Offline

    Bellendian Regular EF Member

    Location:
    Gatwick
    If they are being classed as a separate installation, then surely you would base the bonding conductor csa on the supply conductors for the individual installation?
     
    • Like Like x 1
Loading...
Similar Threads - supply block flats Forum Date
Which power cable do I use with a 1400w power supply? Electrical Forum May 4, 2019
Query about 12 & 24 hour supply New Member Introductions May 3, 2019

Share This Page

Electricians Directory Post a Domestic Job Post a Commercial Job