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PME vs TT for charger

garywwess
Can someone please explain in common scence English (this has to be explained to a customer) ..  why it is permissible for a street light , which in itself is basically a big metal earth rod buried 5 feet in the ground.. is allowed to be PME`d  (customer used to install street lights) yet his charger has to be TT`d  and isolated from the PME at all costs..  his parking space has a street lamp smack in the middle of it ???  I neither agree or disagree with the instructions to do so… just need something in writing to show the customer to prove im not just generating extra income needlessly..

Gary
 
  • Former Community Member
    0 Former Community Member
    There are 4 charging points! Infrastructure requirements should have been, by now, solidly embedded in building regulations and planning.


    And how much would your area DNO charge to supply 2 MVA or more? What % of the build cost would this be?


    Regards


    BOD
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    Valid point Bod but that is what I am getting at. There has to be a coordinated approach. Legislation provides a helpful hand to but it obviously has to be a thoroughly considered, comprehensive, overall  plan that is proffered. 

    By the way, the overspec on disabled parking bays as a result of legislation and the lack of their use in operation is a salutary reminder that things need to be kept under constant review.
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    I think there will need to be a sea change on network investment at all levels,  at the moment it seems to be about keeping the existing network running as long as possible, and just filling in the hot spots.

    However if cars are to be charged in large numbers, like say half the fleet of cars we now have as petrol become electric, then we will need more power generation, an uplift of lots of routes to higher wattage, perhaps 33kV where currently there is 11kV, and an awful lot of new LV cabling.
  • 0

    perspicacious:
    There are 4 charging points! Infrastructure requirements should have been, by now, solidly embedded in building regulations and planning.


    And how much would your area DNO charge to supply 2 MVA or more? What % of the build cost would this be?




    Why 2MVA? That's 5 kVA or 20-odd amps per car for every single one of them.


    I agree that 4 charging points are inadequate - it suggests no more than tokenism.


    400 places multi-storey. Let's say 4 floors of 100 bays each. Make one floor electric. If the average journey is 10 miles (home to shopping centre) and the average stay is 2 hours, and an economical car does 5 miles per kWh, only 1 kW per bay is required to replenish the batteries for the journey to the shops. So now we are down to a supply of 100 kVA, which is much more realistic. If you want to make provision for the journey home, that's still only 200 kVA.


    Or put another way, diversity needs to be applied!


    Most of the time, most peoples' cars are idle. That's usually 8 hours per day at work, and 8 hours per day at night. We are used to putting in loads of fuel in one go - I fill up about 30 times per year. With electric, we will need to get used to little and often.

  • Former Community Member
    0 Former Community Member
    Why 2MVA? That's 5 kVA or 20-odd amps per car for every single one of them.


    Isn't 2MVA a bit of an over estimated for 4 charging points 


    I responded to the concern that only 1% of the spaces had EV charging facility.


    If 50% were deemed an acceptable level and the expectation of a full charge on a 85 kWh pack in 2 hours suggests a 50 kVA charger at least, which in turn suggests 1 MVA.


    And that is on today's expectations when I would have thought that the infrastructure would have at least a 10 year expectation of meeting demand. If it only doubles in use, that's your 2 MVA.


    Factor in that there's already a 120 kW charge point near Tower Bridge, the discussion regarding low usage/city centre/demand etc takes a different angle.


    Regards


    BOD




    .
  • 0
    It is only Tesla pushing the 120kW and 350kw charging options. For cars in a car park at a shopping centre at least, I'd think that  7 or 22kW (1 phase or 3 ) seems most useful.

    But before we rush round installing hardware that will be scrap long before the paint needs re-doing on the car park,  we need some enforced long term standardisation.

    Right now it's a dog's dinner.

    Early adopters may not care, those of us in the second tier who like to buy a five  year old car and run it for another ten may be a different story.

    The choice of connectors depends on the charger type (socket) and the vehicle’s inlet port. On the charger-side, rapid chargers use CHAdeMO, CCS (Combined Charging Standard) or Type 2 connectors. Fast and slow units usually use Type 2, Type 1, Commando, or 3-pin plug outlets. On the vehicle-side, European EV models (Audi, BMW, Renault, Mercedes, VW and Volvo) tend to have Type 2 inlets and the corresponding CCS rapid standard, while Asian manufacturers (Nissan and Mitsubishi) prefer a Type 1 and CHAdeMO inlet combination. This doesn’t always apply however ...


  • 0

    mapj1:

    Early adopters may not care, those of us in the second tier who like to buy a five  year old car and run it for another ten may be a different story.




    That's me (or that is I for the pedants in here - you know who you are ? ). For me, the economics do not favour an electric car at the moment, let alone the old VHS/Betamax conundrum, but I have a spare 3-phase 32 A MCB standing by. ?

  • 0

    perspicacious:
    Why 2MVA? That's 5 kVA or 20-odd amps per car for every single one of them.


    Isn't 2MVA a bit of an over estimated for 4 charging points 


    I responded to the concern that only 1% of the spaces had EV charging facility.


    If 50% were deemed an acceptable level and the expectation of a full charge on a 85 kWh pack in 2 hours suggests a 50 kVA charger at least, which in turn suggests 1 MVA.


    And that is on today's expectations when I would have thought that the infrastructure would have at least a 10 year expectation of meeting demand. If it only doubles in use, that's your 2 MVA.


    Factor in that there's already a 120 kW charge point near Tower Bridge, the discussion regarding low usage/city centre/demand etc takes a different angle.


    Regards


    BOD




    . all this talk of hundreds of public charging points being needed in car parks during the day, demanding masses of power at times of peak demand … really getting tedious..  for those that need to charge up, a trickle charge over the 8 hour work period would be adequate.. the other 90% like myself would have charged overnight, on cheap electricity, and waking up to a full tank that will suffice for a number of days.. I have had my EV for over a year.. times I have needed to use a public charger  … not once..  EV`s .. it`s not Armageddon.. just a slow slide into normality..    fossil fuel car production.. ok, thats Armageddon

    gary.. 




     

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    Concerning separation of different earthing systems: is it permissible to place an earth rod close to the DNO's service cable? I cannot see how they would interfere with each other except in the event of damage to the latter.



    It might depend on the type of the buried cable too - old PILC cables for example tend to have their metal sheath in fairly good contact with the soil (any original hessian oversheath typically having rotted away years ago). Older properties may well have PILC cables supplying them, even if the cable appearing at the cut-out is modern plastic sheathed, as DNOs have a habit of jointing onto existing cables just outside buildings.


      - Andy.

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