Power required calcs / estimate

Discussion in 'Electrics UK' started by mattysupra, 29 Jan 2021.

  1. mattysupra

    mattysupra

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    Hi all, posted up the other day asking for help about if it's possible to do what we would like. Started a new post (this one) with all the info I have collected over the last few days that should answer the questions that I was being asked in other posts. Started a new post as want to try and keep it tidy in one post now I have all the info.

    Basically, its a Marina where we want to increase the supply to the boats and have caravans also.

    We have had DNO out and they have confirmed we have available -
    3 phase, 69KVA with 3x separate 100 amp fuses to isolate

    What we want to have installed is -

    30x 16amp 240v blue sockets (boats)
    15x 16amp 240v blue sockets (caravans) governed to 10 amps per socket
    1x toilets with a 7.5kw shower and 2kw water heater (shower has very rare use)
    There is a clubhouse also that we are going to add up the appliances to work out amps, but we think around an absolute max of 50 amps on a winters evening with everything on.(everything being 4x fridges, 1x electric fan assisted domestic oven , lighting and 2x 3kw water cylinders)

    As for usage, we would never have more than 50% of caravans and boats in use at one time. More like 30%.

    Also they are mainly used in summer, so other than 40/60w tube heaters to prevent freezing in winter, they will peak with a surge of amps when boiling a 2kw kettle for example.

    With that information, is it feasible to do what we want? Would we have plenty of power left? or would you say we are pushing it?

    Thankyou to anyone who spends the time working the above out.
     
    Last edited: 29 Jan 2021
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  3. securespark

    securespark

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    Are you doing the work?
     
  4. JohnW2

    JohnW2

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    The impression I get from the earlier thread is that he is just trying to ascertain "if it can be done" (simply on the basis of 'supply and demand', taking diversity into account) within the limitations of the currently available supply (pending upgrading of that supply in the future when he can afford to have that done), rather than about anyone (whoever) 'actually doing' the work.

    Kind Regards, John
     
  5. SUNRAY

    SUNRAY

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    Phase 1 = 50A in the clubhouse, 45A in the toilet block, not much headroom but in a good looking position.

    Assuming the tourers are averaging 4A each 45x4= 180.

    I think you are in a reasonable starting place.
     
  6. JohnW2

    JohnW2

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    Given the nature of many of the loads (shower, water heating etc.) I think that there would, in reality usually be a lot of headroom (considering 'diversity')
    I think you're probably right, provided that the 4A figure is fairly realistic (which, again with 'diversity', it may well be).

    As I suggested to the OP in the earlier thread, it would probably be helpful if he could get some insight from others running similar enterprises (e.g. from industry-related bodies, discussion groups etc.) as regards the sort of average loads the caravans/boats turn out to be in practice.

    Kind Regards, John
     
  7. mattysupra

    mattysupra

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    No, just trying to see what we can do before we invite people out to quote. Don't want to waste peoples time and travel if what we plan ist feasible.
     
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  9. SUNRAY

    SUNRAY

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    Yes you are quite correct about headroom but I don't know the ins and outs of the clubroom but with the info supplied I feel I made a realistic comment. As I noted before, it's a long time since I've been heavily involved with serious camping but our house averages around 4000KWh per annum or 10KWh per day or 4A over a 10hday and I wouldn't expect a tourer to be much more than that. I also don't know how much effect kettle and Coronation street affect touring.

    OP is for want of a better description an feasibility study and on the face of it I believe there is enough there to proceed with the ideas for expansion
     
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  10. ericmark

    ericmark

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    First is caravan second is marinas it seems both require 16 amp supply.

    I know I have been in caravan sites and marinas where the supply was much less, often 5 amp, and in one marina they had different charge for power depending on the size on MCB and seem to remember used some thing very low like 3 amp. However with canal boats they have large battery banks, often 400 Ah and they have special grid tie inverters which supplement the shore supply when required, so they can draw 6 amp 24/7. The caravans have smaller batteries and they don't tend to fit these devices as in the main holiday only, and batteries are heavy so tend to be smaller, but the power use has increased over the years, mine has duel fuel central heating, and duel fuel water heating, so on arriving on a site, for the first hour load tends to be high, as the water store and caravan is heated, much depends on how well insulated.

    Most caravan sites have the option of hook up, and either you have to select a different plot depending on if power provided or not, or have the socket activated, the latter often a locked lid on the MCB, the problem is if it trips some one needs to reset it, and I have arrived on a site and found I have developed and earth fault and had to reset many times before it was corrected.

    I stopped on a site on the building of Sizewell power station, the site was normally summer only, and had 5 amp to each caravan, think around 50 caravans with a split phase 100 amp supply which was ample in the summer, but in winter the DNO fuse was blowing, so a 80 amp moulded breaker was added to cover the caravan supply, so if there was an over load as people arrived home from work, the 80 amp went not the 100 amp fuse, not ideal but worked. In summer he had no problem, but whole point in paying for a hook up today is so you don't need to be lugging gas bottles, I have a small gas bottle for oven, but years ago used a special low amp kettle, but today use standard 10 amp kettle, the heating has the option of 3 heat inputs, so can reduce it if only 5 or 10 amp supply, but that means it is left one when we go out, with a 16 amp supply we turn it off when we leave the caravan, so reducing the supply does not reduce total use, in fact it can increase.

    My caravan has a 10 and 6 amp MCB, in the main as a result my MCB trips before the site MCB should I go over the 16 amp limit, however if the limit is 10 amp then site over load will trip.

    Likely using 80 amp overload at the distribution board the times it will trip will be few and far between, but for a consumer unit not seen any 80 amp trips, so what has to be asked is if under the control of ordinary persons? I would not think so as using three phase, but this is why we have switch rooms, so the ordinary person can't enter, only skilled or instructed, much depends on location, remember one caravan site owner saying how the local attractions all closed at 8 pm and he would get a surge of power used as the campers returned home together.
     
  11. mattysupra

    mattysupra

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    So in the regs it says that 16amp should be supplied not down rated with a 10amp mcb? Have I understood that correctly?

    As for use, its private members-only club. We won't have visitors booking a pitch etc. All caravans and boats are members only and are stored there all year. The boats leave for holidays, but the caravans never move as people who own them use the actual club grounds as there holiday or more so, for a pee up on a weekend and somewhere to sleep lol.
    All caravans and boats have access to the MCB where they plugin (not the 3 phase main CU board) if they trip. They also all know to use lower-powered equipment at present as we do suffer already with volt drop. However, looking into this, the cables feeding the boats and caravans is way under sized, it was put in many years ago when the boats etc only used a very small amount of power. We know that we have to have new cables installed to rectify this issue. But before we do that, we need to be confident we can provide more power which I think we can going by the comments.
     
  12. JohnW2

    JohnW2

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    Maybe they are yet (more!) examples of badly worded regulations, but the two you quote appear to be requiring that the socket-outlets be 'rated at' not less than 16A - which, taken literally as worded, is very different from saying that that the supplies must be capable of supplying 16A, isn't it?

    Kind Regards, John
     
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  13. ericmark

    ericmark

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    From the description I see no problem with 10 amp supply, BS7671 is not law, it does not need to be complied with, and as @JohnW2 points out it is poorly worded anyway, had it been a caravan club or caravan and camping club site then the campers would expect 16 amp, but in your case any improvement must be welcome.
     
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  14. flameport

    flameport

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    Very likely feasible.
    If people are in the clubhouse, they won't be in their caravans/boats, so the additional power there will be offset by less usage in at least some of the boats/caravans.

    Either get rid of the shower completely, or change to one which uses stored hot water from a cylinder, which will allow much better control of when the water is actually heated, rather than a large load being switched on/off as and when people use it.

    No.
    16A rated sockets should be used - those round blue efforts which the majority of caravans use.
    That's not the same as having those sockets being capable of supplying 16A continuously.
    A 10A MCB doesn't trip at 10A anyway, so short duration overloads of more than 10A could be tolerated.

    If you haven't already, consider a decent sized solar panel installation, which will both reduce the peak loads during the daytime and save substantial sums on the electricity costs.
     
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