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Old incomer connected to four 3 phase cutouts help

Hi all,


I have a very old incomer entering the building that then feeds to 4 x 3ph cutouts. You can see two of the 3ph cutouts in the pic.
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The incomer says on it  - BI Callender's - 4E 150 x 3. I assume this means 3 x 150 Amps? Please do correct me if I am wrong.


1. What is the maximum power I can draw from this system?


2. If each of the 4 Three phase cutouts were loaded with 100 Amp fuses and I was to pull close to that from each fuse. what would happen to the incomer as this would equate to 1200 Amps!


3. Is connecting 4 3ph cutouts to this old beast a reasonable thing to do? Or is it ridiculous?


Many thanks

Simon
  • And that is the conundrum with electric heating. The responsiveness of panel heaters on eye watering day rate or the sluggishness and wastefulness of off peak storage. What we need is one of those new fangled algorithms, seemingly they can solve everything.
  • Hmm given the red yellow blue spots, if original, it should not be fused neutral (that era would be read white and blue or the red white and green that preceded it), though it may well contain asbestos flash pads, in which case the DNO will not want to open it, but either leave it sealed, or if they really have to replace it, they can do that unopened by cutting the supply cable further back.

    The grey box above may contain something like line taps or Henley blocks to split the tails, it looks too small for a bus.

    In any case it is all under company seals, and is not really your problem.

    It may be worth verifying Zs is low enough to blow a 150Amp fuse before the DNO get there, so if it is not, you can get them to do something about that at the same time.

    And that trunking may be mitred, but it looks like it is not earthed, is that the case ?

    Mike.



  • It may be worth verifying Zs is low enough to blow a 150Amp fuse before the DNO get there, so if it is not, you can get them to do something about that at the same time.



     


    I have a Zs of 0.22 measured from a distribution board 2 meters away from the incomer.


  • I had a similar quandary some years ago and eventually an intern arrived from the DNO along with the District Manager to do a onsite inspection, I provided the screwdrivers, they provide the seals.


    I doubt you will get an answer without someone from the DNO coming pulling it all apart and having a good look at it.
  • But could the incomer in question be a fused neutral?

    I doubt they ever put a fused N on a 3-phase system - too much risk of frying loads with 415V L-N. AFAIK even in the old days N was only fused after the transition to '2-wire' circuits.


       - Andy.
  • Many thanks,


    I have just come across this document, some excellent bedtime reading relating to the codes given by DNO's on such matters as discussed above. As well as actions.

    https://www.whatdotheyknow.com/request/482157/response/1173192/attach/10/Annex%201.7%20MOCOPA%20Guide%20Version%203.5.pdf?cookie_passthrough=1


    Enjoy!
  • A total of 150 amps per phase MIGHT suffice for electric heating or might not.

    What is the floor area to be heated ? how well insulated is it ? And as has already been said is electricity to be included in the rent or service charge or will it be metered.

    If not metered, then expect very liberal use.


    Panel heaters vary a lot in loading, but about 8 to 10 amps is common. So allowing for other loads, you should be ok for about ten or a dozen heaters on each phase.

    What about water heating ? Are any showers to be fitted ? Any energy intensive processes likely, table top pottery kilns, or any electrically powered catering to be allowed.

  • Our total floor area to be heated is 950 m2. This works out at about  390A! This does not leave us with much left.


    So it looks lke we are going to need more power to the building.


    Thoughts?


    Regards

    ​​​​​​​Simon
  • Let's hope the rest of the refurbishment includes more than the bare minimum insulation, and double or triple glazing..

    The problem is often that the builders pay for the materials once, and only see that cost, the residents do not see the cost of the insulation, but see the heating bills every winter.

    M.


  • Thoughts?

    Heat pump(s) rather than resistive heating?


    +1 for better thermal insulation.


       - Andy.