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Utility and kitchen circuits

Discussion in 'Electrics UK' started by Homerdoh, 25 Nov 2014.

  1. Homerdoh

    Homerdoh

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    Cracking on nicely with my refurb but need advice on the following before I start phase.
    Do I need to have ring circuits for the utility and kitchen or can I have radials?
    The kitchen will have 5 double sockets, 1 single inside the base unit next to and for the fridge freezer, 1 switched fuse connection unit feeding 1 single socket for the dishwasher. This will run off a 32a mcb.
    The utility will have 2 double sockets above the counter and 1 switched fuse connection unit feeding another double socket under the counter for the washing machine and tumble dryer. This will run off a 32a mcb.

    Not sure if it's relevant but one of the kitchen double sockets will feed the counter top microwave.

    Also, do I need to include the extractor fan in the kitchen radial/ring or does that have its own run?

    Regards

    Homer
     
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  3. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    You can construct the circuits in either the ring or radial method, providing you get the load rating correct for the appliances and the cable rating size suitable for the protective device. You will have to check on any derating factors that may apply, regarding the method of installation, if none do, then 32A on either 4.0mm2 radial or 2.5mm2 ring would be fine.

    Ex-fans can be powered from either a socket circuit, a lighting circuit or circuit all of it's own. But would require down fusing in accordance to manufacturers instructions.

    My concern would be double socket-outlet on 13A FCU, this supplying two kitchen appliances. You will only have 13A available for the double socket, having both appliances operating at the same time could present an overload.
     
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  4. Homerdoh

    Homerdoh

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    Ok so I should have 2 switched fuse cu's one for tumble dryer and other for washing machine.
    It'll be 2.5mm so I guess it's rings then!
    So a spur from the live feed to the kitchen light will be ok for the extractor?

    Regards

    Homer
     
  5. Taylortwocities

    Taylortwocities

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    Subject to the usual load considerations, you could feed it from the lighting circuit.
    It is more usual to power a kitchen fan from a (3A) FCU on a ring final.
     
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  6. ericmark

    ericmark

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    You should have radials if being pedantic because the large items like washing machine, tumble drier, dish washer are all over 2kW and are too heavy to be classed as portable they should have dedicated circuits.

    Often this is not the case. It is common to have conductors in parallel where two 2.5mm² cables feed a grid switch simply because you can't get two 4mm² cables in the terminals of the grid switch. If the cables only feed the grid switch then they are conductors in parallel not a ring which then means the rules for 2kW do not apply. The cables from the grid switch should in theroy be not more than 3 meters. This would be considered as dedicated circuits.

    The ring has to be so the load current in any part of the circuit should be unlikely to exceed for long periods the current-carrying capacity of the cable (Regulation 433.1.5 refers). It is in the main down to the length of the cable to first sockets compared to total length of the ring which will determine if overload is likely. The ring has a problem in sockets near to one end will draw power mainly from that end and a pair of sockets very near to the consumer unit could draw too much current. This is in real terms unlikely but is one reason why we have the 2kW rule.

    Looking at logistics having radials means a larger consumer unit except for grid switch design but means a fault should not cause loss of all circuits. There has been great debate over supply to fridge/freezer if dedicated it is less likely to fail but also you may not be noticed if it does fail.

    There is also debate if circuit includes RCD protection or not.
     
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  7. ban-all-sheds

    ban-all-sheds

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    When you applied for Building Regulations approval, what did you say, or allow to be said or assumed, or by default agree to, about who would be doing the electrical work and how compliance with Part P would be achieved?

    If you promise one thing and then do another you could find that the council won't give you a completion certificate.
     
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  8. ericmark

    ericmark

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    You are of course correct Clwyd no longer exists but Wrexham, Denbighshire, and Flintshire are all Welsh so kitchens still need LABC involvement.

    I found Flintshire were very insistence on qualifications although they also seemed to have no idea what a C&G 2391 was.

    The fee was £100 plus vat for first £2000 worth of work throughout Wales it may have gone up but not fixed by council but Welsh Assembly. Since I was involved the rules have changed and they can now charge for contractors used to inspect and test which means if it fails you also pay a second time for inspection and testing.

    Mothers kitchen I used a scheme member electrical firm just not worth DIY you can basic regard first £200 of sparks labour as being free as you will pay that to council to DIY.
     
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  9. JohnW2

    JohnW2

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    It would certainly be desirable to have separate sockets for the dryer and washing machine. However, you wouldn't really need switched FCUs - there will already be 13A fuses in the appliance's plugs, so there's no point/need for further 13A fuses in the FCUs. If you want above-counter switches, they could theoretically just be (appropriate) switches, rather than FCUs.
    If this work has yet to be done, why does it necessarily have to be 2.5mm²?

    Kind Regards, John
     
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  11. EFLImpudence

    EFLImpudence

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    Wrong way round.
     
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  12. ban-all-sheds

    ban-all-sheds

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    Seems to be a bit of a haphazard approach to circuit design.
     
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  13. JohnW2

    JohnW2

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    It does. However, if there were little to choose, design-wise, between a 2.5mm² ring and a 4mm² radial, I suppose the fact that one had a lot of 2.5mm² cable to hand might become a deciding factor!

    Kind Regards, John
     
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  14. ban-all-sheds

    ban-all-sheds

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    That depends on whether you think any new ring finals should ever be created.
     
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  15. Homerdoh

    Homerdoh

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    I don't really want 2 switches above the counter for dryer and washer but thought it had to be done that way, is there a better way round it?
    Do you mean just a normal switch for each?

    Electrician hasn't started yet but I want to get as much ready as possible including having all materials on site. I already have loads of 2.5mm which is why I thought it'd have to be rings as prenticeboyofderry suggested in post 2

    regards

    Homer
     
  16. Homerdoh

    Homerdoh

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    Is it? I thought the options were 4mm radial or 2.5mm ring?

    regards

    Homer
     
  17. EFLImpudence

    EFLImpudence

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    Yes, but we use 2.5mm² for rings; not fit rings because we don't have any 4mm².
     
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