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3 Phase to single phase

Discussion in 'Electrics UK' started by morg, 5 Aug 2020.

  1. morg

    morg

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    Hi, looking for some advice

    I've just rented a small workshop which has 3 phase electricity, it is a shared unit.

    None of my work requires 3 phase, single phase is all I need but I would like a meter installed as we would share electric costs.

    I was thinking of getting an electrician to install a 6 way consumer unit with a meter for my requirements, is it possible to install a single phase consumer unit in a commercial unit?

    I've worked out my max consumption at full load:

    3kW - Machinery (max load, would never use 3kW at the same time, more like 2kW max)
    6kW - Heating Elements (2 x 3kW each)
    3kW - Sockets ( 3 x twin sockets, would never use more than 1kW at a time)
    1kW - Lighting, alarm and perhaps cctv

    With this meter installed:
    https://www.tlc-direct.co.uk/Products/RDCRED60.html
    or https://www.tlc-direct.co.uk/Products/RDCRED100.html

    Cheers for any advice
     
    Last edited: 5 Aug 2020
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  3. ericmark

    ericmark

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    Yes it can be done. However with commercial units you may have other considerations. Like the electricity at work act, so unlikely a DIY job.
     
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  4. morg

    morg

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    Thanks, yes I will be getting someone in to sort it out, won't be touching anything
     
  5. plugwash

    plugwash

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    Do you know anything about the existing wiring arrangements? both for your space and the building as a whole? Do you know anything about the previous use of your space and the use of other parts of the building?

    Adding up your listed loads gives 13kW, I suspect you are being rather pessimitic though and realistic maximum load is more like 9-10KW or so. So about 50A or so on single phase. That is a big chunk of the per-phase rating of a typical small commercial supply.

    Ultimately I don't think the question of whether you can use a single phase meter and CU can be answered without knowing a lot more about the installatoin as a whole.
     
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  6. conny

    conny

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    Your electrician will also have to make sure the 3 phase supply also has a neutral to enable single phase.

    Certainly not a DIY job but simple enough for a qualified spark, preferably industrial/commercial as opposed to a domestic guy.
     
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  7. JohnW2

    JohnW2

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    As has been said, you need a competent electrician who has seen the on-site situation to give advice.

    However, before you get too involved in considering the mechanics, it might be worthwhile for you to consdier, and look into, the financial implications. ...

    ... Are you saying that you want to use just one phase of your supply (with a separate meter, just for you), with others using the other two phases (either jointly or separately), separately metered? If so, as has been said, that could certainly be done, but I would think that the supplier would then regard it as a separate supply, with the other two phases being either one or two other separate supplies - that would mean a total of either two or three 'standing charges'. I would be very surprised if a supplier would allow you to have two (or three) separate meters on 'one supply'.

    Kind Regards, John
     
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  8. plugwash

    plugwash

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    I assumed he was planning to install a private meter to measure his share of the electricity consumption.
     
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  9. morg

    morg

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    Thanks, yes of course this a job for a qualified person, I was just looking for info/advice on the cheapest option I guess.

    I probably won't use more than 9-10kW at full load as you suggest!

    There is already a few twin sockets there (Type G), so I assume these sockets are on single phase circuit. Plus the lighting (standard 8ft fluorescent tubes) must be single phase also.

    @ John
    All of my equipment/tools don't require 3 phase use, while the other occupants would be using the 3 phase for their equipment.

    At the moment the electricity is shared so there is no way of knowing who is consuming the most/least - I would just need my circuit/DB metered, to save arguments over the bill.

    How would the supplier know if we fitted a check meter and why would it be frowned upon? It would merely be an accessory/tool only to measure approx usage on my circuit?

    The bill comes in from the supplier 'as a whole' then we work out my usage, compare it against total usage (from suppliers reading) then work out the difference on who pays what.

    Thanks for the advice
     
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  11. morg

    morg

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    Yes exactly what I need (y)
     
  12. JohnW2

    JohnW2

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    Oh, fair enough, I misunderstood what you were suggesting/proposing.

    If what you are talking about is a 'private' single-phase meter to enable you to appropriately split ('amongst yourselves) the single (3-phase) bill between users, then that's easy enough and electrically-speaking, almost trivial to do.

    In fact, you do not necessarily even need a 'meter' in the usual sense. You could use a 'clip on energy monitor' on your single-phase supply, or you could get your electrician to include an energy-usage monitor module in the single-phase CU you plan to have fitted.

    Kind Regards, John
     
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  13. plugwash

    plugwash

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    Sure, it's perfectly normal to run single phase circuits off a 3 phase supply.

    The issue is that one normally wants to spread the single phase loads among the phases. Otherwise you can end up overloading one phase while others still have spare capacity. Putting all of your load on one phase may or may not be possible while maintaining an acceptable balance in the system as a whole.
     
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  14. SUNRAY

    SUNRAY

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    Realistically it's no different to having a single phase supply with a single phase meter, just like in a house.
    As long as the total load on your phase of you and all the other occupants doesn't exceed the the supply it will be fine.

    So the real question. You are likely to be using 10KW or 43A leaving 57A
    What is the supply rating/fuse?
    What load are the other occupants likely to be drawing?
     
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  15. flameport

    flameport

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    Possible but not something that is desirable, necessary or to be recommended.

    If you only want a few circuits, a 2 or 4 way 3 phase board would be a far better option, those would provide up to 6 or 12 single phase circuits and still retain the possibility of one or more 3 phase circuits as well for the inevitable day when some new piece of 3 phase equipment arrives.

    For metering, a meter is installed. A 3 phase one in the supply to your new board.

    All of that is ordinary, everyday stuff that any decent electrician could install.
     
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  16. winston1

    winston1

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    John, I'm surprised at you. You must know they give inaccurate results as they don't measure power factor or voltage.
     
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  17. JohnW2

    JohnW2

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    We've been through this before. For the OP's purpose (deciding how to share the electricity bill between users) such a monitor would be more than adequate.

    Indeed, in the context of long-term measurement on a whole installation, once one has established an average voltage and average PF to assume, they are incredibly accurate. Over a period of about 3 years' monitoring, my supplier's meter recorded usage of 15,248 kWh day and 12,372 kWh night. During that same period, my clip-on monitoring system recorded 15,237 kWh day and 12,353 kWh night - under-readings of 11 kWh (0.07%) and 19 kWh (0.15%) respectively.
     
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