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Old incomer connected to four 3 phase cutouts help

Simon M
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.
9f8642aebed8db60e40f7a2578ffd3a3-original-02.jpg


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
  • 0
    Simon M:

    Thank you for the replies very useful.


    The property is a listed 200 year old foundry converted to offices in the 60s/70s.


    The intended use is education, arts spaces, maker spaces, small studios etc. So no dwellings.


    Originally heated by storage heaters which have now been removed, we are at the strip out stage but plan to have panel heaters in the rooms (number to be decided).


    As the storage heaters were huge old things I am presuming they would have used a lot more juice than a modern panel heater. Albeit on economy 7. 


    I just have to do the calcs.


    Many thanks as this puts my mind a bit more at rest regarding the power we have available.

    I do have the DNO coming out in an attempt to try and get them to upgrade the incomer but I'm not holding my breath.


    Regards

    Simon.


    Change the usage to a gym, then they will not need any heating.


    Z.


  • 0
    AJJewsbury:
    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.


    AFAIK, fused neutrals were primarily used on DC systems, and sometimes retained on AC systems that had formerly been supplied with DC.

    There are still existing fused neutrals on AC systems but I suspect that these were once DC.


    A far less common reason would be a system that whilst AC originaly, once had BOTH poles of the supply live. For example a 220 volt circuit derived from a 3 phase 4 wire system at 127/220 volts. That would REQUIRE a fuse in each pole of the supply, and this might have been retained when the installation was later connected between one phase and the neutral of a 3 phase 4wire system  at 240/415 volts.


  • 0
    UKPN:

     An industrial unit from the 1960s, hence the TPN 150 amp service .It then seems in later years this became a collection of offices hence the multi cut outs. 

    Are the (12) meters still installed? 

    If there are to be that number of "units" and depending on the maximum power requirement, the ideal and cost effective solution may be to upgrade the existing cut outs and most likely upgrade the incomer, (which would be a minimum of 200 amp) I note the tails are insulated and sheathed, so modern.

    It appears there is a satisfactory Ze. 

    The space heating seems to be a general installation so likely to be part of a landlords supply.


    This project depends on as always, the maximum power reqd. This will be declared to the DNO and they will take it from there. 

    If the required load exceeds the available capacity, as a starter a new cable will be need to be laid. Depending on condition, they may require a Ryefield. The consumers switchgear may need to be renewed. 

    Earthing and bonding will almost certainly need upgrading to (TNS) new standards. 


    Pretty straight forward really. Good luck with that.

    Regards, UKPNZap

     


    Thank you, again invaluable information.

    I may have more questions, forgive me.


    Regards

    Simon


  • 0
    An industrial unit from the 1960s, hence the TPN 150 amp service .It then seems in later years this became a collection of offices hence the multi cut outs. 

    Are the (12) meters still installed? 

    If there are to be that number of "units" and depending on the maximum power requirement, the ideal and cost effective solution may be to upgrade the existing cut outs and most likely upgrade the incomer, (which would be a minimum of 200 amp) I note the tails are insulated and sheathed, so modern.

    It appears there is a satisfactory Ze. 

    The space heating seems to be a general installation so likely to be part of a landlords supply.


    This project depends on as always, the maximum power reqd. This will be declared to the DNO and they will take it from there. 

    If the required load exceeds the available capacity, as a starter a new cable will be need to be laid. Depending on condition, they may require a Ryefield. The consumers switchgear may need to be renewed. 

    Earthing and bonding will almost certainly need upgrading to (TNS) new standards. 


    Pretty straight forward really. Good luck with that.

    Regards, UKPNZap

  • 0
    Thoughts?

    Heat pump(s) rather than resistive heating?


    +1 for better thermal insulation.


       - Andy.
  • 0
    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.


  • 0
    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
  • 0
    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.

  • 0
    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!
  • 0
    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.

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