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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
    Only the owner can see the google drive image you are linking to - you presumably are logged into your google account and can see it. Sadly we can't...


    You can upload files to the forum server and then we can all see them.  In the composing post window, it is the button next to the smily face that looks like a temperature chart that allows you to upload an image, or the paper clip that allows you to attach a local file.


    It may well be 3* 150amp fuses in the cut-out but it is an odd number, but then BI go back to the days of rewireable service fuses, and fused neutrals, so anything is possible. If it was new 150mm2 cable size comes to mind, but this will be well and truly pre-metric I assume.


    Lets see it, and the size of the incoming cable. (but in flats it is quite common to see several flats each with 60A or 80A fuse, on a 100A incomer... normally without issues.)

    mike.

  • 0
    Thank Mike,


    I have edited the post, I think.


    I don't have a pic of the incoming cable, I can get one tomorrow.


    I can tell you the cable has rolls of lead where it terminates and the earth is connected to this.


    Possibly 2 inch thick.


    Many thanks.
  • 0
    There is nothing unusual in one incoming cable serving several sets of cut out fuses and meters.

    A "100 amp" cut out indicates that it is suitable for fuses of UP TO 100 amps. It might contain a 100 amp fuse, or might contain a smaller fuse such as 60 amp or 80 amp, or less commonly 40 amp.


    The total fuse ratings often exceed the available capacity, on the grounds that few consumers use the maximum, and that even if a consumer DOES use the maximum, their neighbours hopefully will not.


  • 0
    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!

    Nah, just 400A/phase. Even at 40% diversity (DNOs usually use a lot less) it's not much above 150A. I suspect the original cut-out is fused, so if you did keep up a 400A load for many many hours, you might blow them.


    Presumably it's feeding multiple domestics premises (flats?) - in which case unless the primary space heating is entirely electric (e.g. storage heaters), I doubt it would even get warm.


       - Andy.
  • 0
    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.
  • 0
    Why would old storage heaters use a lot more juice than a modern panel heater given that they are both electric and therefore 100% efficient?
  • 0
    Simon M:

    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.


    If they say that it will be fine for the intended use, what is there to complain about?


  • 0
    Grumpy:

    Why would old storage heaters use a lot more juice than a modern panel heater given that they are both electric and therefore 100% efficient?


    Indeed, you are correct.

    I was thinking more on the lines that a panel heater can be switched off when a particular room is not in use. We anticipate not all rooms to be occupied throughout the day.

    Thus saving power. 

    The problem with storage heaters is you cannot just turn them on and get instant heat.

    I probably need to read up on space heating and what would be more suitable.


    Regards

    Simon.


  • 0
    Chris Pearson:
    Simon M:

    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.


    If they say that it will be fine for the intended use, what is there to complain about?




    Nothing, and that's what I am hoping for :)

    Though I would like it in writing so I can keep the trustees happy.

    But could the incomer in question be a fused neutral? 


  • Former Community Member
    0 Former Community Member
    The intended use is education, arts spaces, maker spaces, small studios etc. So no dwellings.


    Will their rent include electricity, as if not metered and charged to them, everything will be left switched on............?


    As to what the DNO will supply, it will be up to you to ask for an Authorised Supply Capacity (ASC) and they will within reason supply whatever you ask for, at a price naturally. But good luck on asking them for what they will presently supply you with..............


    Regards


    BOD just back from site visit to client who wants a supply to a proposed dwelling 520 m from his existing meter which in turn is 100 m from 15 kVA HV Tx.

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