What size Armoured cable should I use

Discussion in 'Electricians' Talk' started by An dy1962, Apr 25, 2016.

  1. An dy1962

    An dy1962 New Member

    Hi
    I want to run power down to a summer house could someone advise me please
    Its less than 25m from the house and the cable will be under ground there are 3 double ring main socket and a single light circuit going to a small garage type consumer unit inside the summer house.
    The lights are LED spotlights 4W
    And the plug sockets will run a 2KW heater in the winter
    And I will over estimate another 3KW
    So a 5KW and 22amps draw maximum at one time what size Armoured cable should I use will 3 core 2.5mm be ok or should I go higher, I think the maximum draw will be less that 3.5KW.
    I have done some calculations and 2.5mm should be ok

    Any Advice would be appreciated

    Andy
     
  2. JP.

    JP. Screwfix Select

    Morning Andy. 6mm or even 10mm would be far superior - headroom is the name of the game..;)
     
    parahandy, KIAB and An dy1962 like this.
  3. sparky Si-Fi

    sparky Si-Fi Screwfix Select

    My advice is as follows. .

    All that you surmise to do will be done by your spark as he is the one that will design install certify and notify Building control as all of this comes under the law of the land my old flower and is not a DIY task

    Building control will send a spark out to inspect your job but expect to stump up at least £300.00 for the privilege

    A self certification electrician will be the fraction of the cost BUT will not use his license number for YOUR work you have done yourself

    Do it correctly as you don't want this to bite you in the **** upon the day you want to up and move!

    10+ years down the road and the word has still not gotten round regarding Part P!
     
    nffc and An dy1962 like this.
  4. An dy1962

    An dy1962 New Member

    Sorry should have said I know you election get touchy about this, I will be just laying the cable but an election will make the final connection at both ends as money is tight although I am a fully qualified auto election used to working with looms over 300 individual wires. The cable will be buried at a depth of 3ft on a gravel bed covered in sand then covered with 12inc of soil then a strip of yellow Warning buried Cable tape over the length of the cable then the rest of the soil covering that. I will video the important parts of the cable laying so the election can see how it was done if they want, I want to get this done myself to save a bit of money, would like some advice what size cable to fit don't want to go over the top with the cable as nothing else will be added to this I don't expect the max load will reach 3Kw.
     
  5. An dy1962

    An dy1962 New Member

    Thank you to you both for your help so far
    Andy
     
  6. madhatter1uk

    madhatter1uk Screwfix Select

    How sure are you that you'll not use it as a workshop I'd want a kettle down there or water heater.
     
    An dy1962 likes this.
  7. An dy1962

    An dy1962 New Member

    May be a kettle and the 2 Kw heater in the winter a little radio with a transformer on it plug the lawn mower in but not all at once. it just a summer house I am not looking at spurring off to other builds.
     
  8. madhatter1uk

    madhatter1uk Screwfix Select

    I wouldn't, not at 25metre, I'd go higher than 2.5
     
  9. An dy1962

    An dy1962 New Member

    So trying to keep the cost down would you say I would be ok to run 4mm instead of 2.5mm
     
  10. JP.

    JP. Screwfix Select

    Use 6mm An - its a lot of graft to run the cable. I like the 3 core you portray, cannot stand 2 core with armour as cpc, its not cricket..even though the tables might show it as ok.

    What supply type are you on An?

    And don't forget about discrimination - ie "2.5mm - say 20 amp mcb at db1, then at db2 what are you going to switch? 10 amps? Hence the 6mm. Myself would use 10, but I am only diy.
     
    Last edited: Apr 25, 2016
    KIAB likes this.
  11. JP.

    JP. Screwfix Select

    Nice one Hat.
     
  12. KIAB

    KIAB Super Member

    Someone with brains,it infuriates me as well, it's such a shoddy way of doing it, 2 core with armour as cpc.

    Last lot of swa, I got from here.

    http://www.superlecdirect.com/p-xlp...7-steel-wire-armoured-cable-harmonised-cores/
     
    Last edited: Apr 25, 2016
    nigel willson likes this.
  13. An dy1962

    An dy1962 New Member

    240V straight from main fuse box B40 5940S nothing else will run off so its got it's own dedicated supply
     
  14. An dy1962

    An dy1962 New Member

    I Will only use 3 Core XLPE Cable despite the cost
     
  15. JP.

    JP. Screwfix Select

    An I've got to go but use 6mm - but hey at the end of the day you do what you want to.

    Is your supply type at db1 (house) TT?
     
    An dy1962 likes this.
  16. KIAB

    KIAB Super Member

  17. JP.

    JP. Screwfix Select

    An dy1962 and KIAB like this.
  18. An dy1962

    An dy1962 New Member

    Thank you all for your Help 6mm 3 Core is my best bet then :)
     
    madhatter1uk likes this.
  19. JP.

    JP. Screwfix Select

    Even better - excellent.
     
  20. KIAB

    KIAB Super Member

    nigel willson and An dy1962 like this.

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