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Minimum Voltage at incoming supply point

FlyWheel
Retired now and not up to date with reg’s since 16th. Helping advise a friend. Currently they have 100amp single phase supply and whilst the no load voltage is up at around 238 volts, as the circuit is loaded, voltage drops off substantially. Even with a load of 50 amps, ie, half the supply fuse rating, voltage is slightly below the -6% limit, at around 215 volts, further load simply pushes voltage significantly lower, and by extrapolating measured data, it would be nearer 170 volts with a load of 100 amps, is this acceptable? I plan measuring Ze and pfc this week as a guide perhaps to supply loop impedance and, which I suspect must be causing this excessive drop. I’m aware of the ESQCR reg’s although need to update myself, but are there any other regulations that apply?

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    Good times Alan, Did you ever visit Walter's International Club there in those days (Valley road, near town centre), I've had some great evenings there, and meeting up with a guy that sang there in those days on Wed evening. He sang with the then Wild Oats, but these days, just enjoying his retirement entertaining us in the Vulcan once a month, where the landlord Trevor is also an amazing guitar player.

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    Nice one, I look forward to seeing their reply!
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    "Is that still the career path?

    Thank you for asking. For the traditional craft apprenticeship route, UKPN is currently training 93 apprentices in how to repair, maintain and connect overhead power lines.(lines people), underground cables (jointers) or electricity substations (fitters)


    Regards, UKPN
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    Perhaps the agreed supply capacity is "whatever the network can supply without the voltage dropping below 217 volts" Or put another way, "if the voltage drops below the statutory limit, this must be the customers fault for overloading the supply"
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    One of my former customers is on the Sunday Times Rich list, he only has a four bedroom house, but it is the bed four bedroom house you will probably ever see.

    The house has two three phase supplies rated at 60-amps, one in the house and the other one in the swimming pool house with the pool being electrically heated with traditional heaters.


    Another customer has ground source heat pumps and a solar photovoltaic array installed a few years ago which he makes a profit on when it’s running, so leaves the heating on whilst on holiday, though that may not be possible with a new set up.


    As I passed comment above the answer to the problem is probably to throw some money at it as an investment that will reap future benefits, however it does need the DNO, metering services and suppliers to cooperate and getting them to do so can be a long process.


    Andy Betteridge 




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    But of course, getting the supply limit data out of them before such a situation is detected, may be like trying to get blood out of a stone, so I suggest assuming their supply fuse represents that "ultimate" limit is not unresonable.
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    It might be easier to get blood out of a stone then try to pass the whole assembley thru the eye of a needle
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    I think the simple truth is that in many cases the DNO don’t know the data, because the network is not being used as it was designed.


    Earlier this year I did a job in South Wales and posted some pictures of the suppliers tails at the intake, it is the only overhead five wire TNS earthed system I have seen, I definitely have not seen such an arrangement in this neck of the woods.


    Sat having a coffee one evening I followed the cables both ways on Google Street View, I was genuinely surprised how many homes are being supplied by this run of cables with probably at least a third of the homes having been built and added to the supply during the time the cables have been in place.


    The must be many places where the network is already stressed and simply cannot cope with EV charging and heating loads unless the extra demand is applied overnight.


    Andy Betteridge
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    FlyWheel:

    But of course, getting the supply limit data out of them before such a situation is detected, may be like trying to get blood out of a stone, so I suggest assuming their supply fuse represents that "ultimate" limit is not unresonable.




    They should know the ASC for every property, whether specifically applied for, or a default. The information is needed for the calculations for a new connection, to determine what (if any) network reinforcement is required as part of the quote. It is likely that the ASC will be less than the supply fuse. Some DNOs in the UK fitted a 100A fuse regardless, others tried to fit a fuse closer to the ASC. 


    Whether the DNO were aware of all the additional load tagged on is questionable, however it will be obvious from the voltage / current traces they have, together with a rough size of the motor loads, and their start / stop regimes. The cost of the supply upgrade will depend on what is needed to deliver three phase to the property. It may be easy, or it may be difficult (read “expensive”). 


    Regards,


    Alan. 

  • Former Community Member
    0 Former Community Member
    With this being the 100 post total, apart from the social updates, we've yet to actually be told what kVA was applied for and its associated cost.............Why is this?

    and an upgrade price of £8k would be a bargain.


    Regards


    BOD

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