3 Phase Board - Wired single Phase?

Discussion in 'Electricians' Talk' started by Jitender, Nov 23, 2014.

  1. Jitender

    Jitender Screwfix Select

    Just trying to get my head around this. My place of work had a new CU installed a few months ago. This was installed by a local NICEIC registered company.

    This is the picture of the previous installation, I assume its taking 3 of the phases, to power each individual board with a separate board.


    Old Installation

    upload_2014-11-23_18-37-45.png

    upload_2014-11-23_18-38-44.png


    New installation


    The mains switch is a three pole switch dis-connector (125A 3 pole)

    upload_2014-11-23_18-57-37.png


    upload_2014-11-23_18-40-40.png



    upload_2014-11-23_18-51-50.png

    L1 -L2 -L3 all linked so is in effect a single phase board.

    My question is why the Neutral wire does not go into the switch, so if the main switch is switched off, the neutral will still be present? Should a 4 pole switch have been fitted or better an A type commercial board?
     

    Attached Files:

  2. Caddy

    Caddy Active Member

    Well fitting a single phase board system, probably a stacked type would have been my option, The problem with doing it this way is it can be easily overloaded with so many spare ways and your not switching the neutral (which may not be needed in this instance, as you can undo the neutral link form the board) but a 4 pole switch could have been fitted if needed. Im not sure there is anything specifically wrong with linking out the switch as it is in effect a large single phase board now.
     
    Jitender likes this.
  3. stu1312

    stu1312 Member

    **** way to turn a three phase board into a single phase one should of used a proper linking kit not loops of cable
     
    Jitender likes this.
  4. Jitender

    Jitender Screwfix Select

    The SWA used is 3 core 25mm.

    This was the main switch that supplied the original 3 separate boards. The original SWA wire was 4 core.


    upload_2014-11-23_19-30-7.png

    This main switch 100A, was fitted after and supplies the 3 phase board, notice the 25mm tails. don't know why they wired it single phase?


    upload_2014-11-23_19-31-18.png
     

    Attached Files:

  5. Caddy

    Caddy Active Member

    Nice to see the secured the cables... So did they replace the original 4 core swa with a 3 core swa?
     
  6. Jitender

    Jitender Screwfix Select

    Yes the SWA -it was all replaced, could have used cleats.
     
  7. spinlondon

    spinlondon Screwfix Select

    Seems a bit wierd to do it this way.
    They have 3 phases, they could have run 3 phases to the 3 phase board, and then used it to supply single phase circuits across the 3 phases.
    Now they have only one phase loaded, and have reduced the maximum load available load.
     
    Last edited: Nov 23, 2014
    Jitender likes this.
  8. Caddy

    Caddy Active Member

    think someone *****d up then... I'd guess they ordered 3 core swa for a 3 phase board but someone forgot about the neutral.... depending on what the quote / estimate said you may have some come back for them to replace the cable for a 4 core, especially as now you wont be able to install any 3 phase equipment onto that board.
     
  9. Caddy

    Caddy Active Member

    and rather then having the original boards spread across 3 phases you have now loaded one phase.
     
  10. Jitender

    Jitender Screwfix Select

    I'll talk to the facilities manager next week and see if I can dig out the quote.

    Regarding overload, I don't think they would be able to add any further circuits, so they could have opted for a smaller board instead of the current one.

    Also should they have given a legend providing the details for each circuit. i.e. no of points served and cable sizes etc?
     
  11. Caddy

    Caddy Active Member

    Well the circuits appear labelled that will suffice, however you could always photo copy the installation certificate, in whole or just the circuit details, and put a copy in the board as it will have more specific details as you describe
     
  12. Caddy

    Caddy Active Member

    I can't see from the picture but having a label on the front stating "Single phase supply only" or similar would have been a good idea in-case some one thinks its a 3 phase board
     
  13. spinlondon

    spinlondon Screwfix Select

    Something else that should be considered, is whether there is a 3 phase meter?
    Is a 3 phase meter more expensive than a single phase meter?
     
  14. Jitender

    Jitender Screwfix Select

    Just had a look at the Eaton broucher.

    At present they have a 125A TP (triple pole) configuration

    The electrician could have opted for a:

    Switch disconnector kit SPSN (including single phasing link)

    As Stu1312 said.
     
  15. Jitender

    Jitender Screwfix Select

    This is the labeling at present, notice the one 16A MCB been labelled 'UNKNOWN'.




    Can't show the front due to name of co., but it has 3 labels:

    1) Name of co.
    2) Label to identify two colour cabling used.
    3) Label stating that the installation should be inspected in 5 years time.
     

    Attached Files:

  16. Lectrician

    Lectrician Screwfix Select

    You can get a single phasing kit for that board which shorts the busbars together at the top, and provides a DP switch at the bottom.

    That's what should of been used.
     
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  17. Jitender

    Jitender Screwfix Select

    This is the old and now redundant 3 pole switch fuse.

    upload_2014-11-24_21-54-7.png


    Where is my screwdiver?


    Found these tools left in the trunking.

    upload_2014-11-24_21-53-8.png


    2 x lines taped up, not sure if they are live?

    upload_2014-11-24_21-53-25.png


    this looks like the electric meter as its labelled DB1. 3 phase - 4 wire.

    upload_2014-11-24_21-58-7.png
     

    Attached Files:

  18. Caddy

    Caddy Active Member

    So they have completely butchered a 3 phase supply and turned it into single phase?? that makes no sense what so ever.... one thing to check on if thats the case, is how you are charged for the 3 phase supply. Im not sure on specifics of 3 phase charges but i know a customer of mine had loading checked across phases because they were charged a rate for the highest current draw on a phase.. Something to do with keeping the suppliers phases balanced as well so they charged you if you drew a lot on any single phase... Not sure the same applies in your situation but in any case you could have gone from 90A across 3 phase to 90A on a single phase..
     
  19. Jitender

    Jitender Screwfix Select

    This is the schematics.

    the location of the CU is First Floor. The old ones were 1A, 1B, 1C.
     

    Attached Files:

  20. Jitender

    Jitender Screwfix Select

    20141125_183316.jpg These are the remaining 2 phases which are energised.

    My book says the use of electrical insulating tape as the sole means of enclosure for termination is not acceptable.

    What should have been done?

    I would have removed them from the system so risk of shock is removed.
     

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