what size cable for shed ?

Discussion in 'Electricians' Talk' started by paul seabright, Jan 13, 2019.

  1. paul seabright

    paul seabright New Member

    i am a diyer with a bit of site time and i am getting a proper spark to do the job but just need some input from outside . i have a large shed that i will be using the odd power tool drill / bench grinder and will have a tv and electric heater we have got 16mm armoured to run the 25m down the garden . what i need to know is what size cable do i need to run the 6m from my fuse box in my home to the external wall box where we will join to the armoured . i have been told 16mm T&E but then told by another spark this is exssesive and i only need 6mm both qualified sparks but who do i listen too

    thanks for reading and thanks in advance to anyone that takes the time to help a poor diyer
  2. Coloumb

    Coloumb Screwfix Select

    It depends what size the protective device is in the CU. In any case you will want your feed on the non-RCD protected side of the CU so that pretty much rules out using anything other than SWA for the complete run.
  3. sparky steve

    sparky steve Screwfix Select

    Just employ your spark and he will take care of it all for you
  4. rogerk101

    rogerk101 Screwfix Select

    The expensive bit is the 16mm SWA (armoured cable), and you say you already have 25m of that ... enough for the external/underground part of the run.
    The cheap bit is the 6m you need of normal T&E for internal use.
    If it were mine, I'd future proof the whole thing and stick with 16mm throughout, i.e. just bite the bullet and get 6m of 16mm T&E. Short lengths like that can easily be picked up off eBay for dirt cheap and they're unwanted offcuts from longer jobs.
  5. spinlondon

    spinlondon Screwfix Select

    The advice to use 6mm2 cable, must be based on the rating of the over current protective device.
    Wonders why you are using 16mm2 armoured?
  6. Bazza-spark

    Bazza-spark Screwfix Select

    What size do you load and voltage drop calculations indicate?

    Kind regards
  7. unphased

    unphased Screwfix Select

    It is frustrating to read posts like this. They are peppered with so much nonsense its untrue. Who on earth 'told' you to use a 16mm2 armoured cable for a shed? Do you have hundreds of pounds to waste on over sized circuits? Sheds rarely, if ever, require more than 13A, (an extension lead load), to quite adequately power a socket or two and a light. Any decent electrician would be able to calculate the size of cable you would need. All I am seeing in your post is guesses. Guessing on the size of the cable. If you want to guess then you are going about it all totally the wrong way. 16mm2 armoured. What a joke. There is a detailed procedure in BS7671 for how to size a cable and it would take about ten minutes to do it.
  8. Comlec

    Comlec Screwfix Select

    I wonder if the OP has 16mm diameter cable rather than 16mm csa cable.
  9. unphased

    unphased Screwfix Select

    I dread to think. He is only mentioning the cable, as though that's the only consideration.
  10. Hans_25

    Hans_25 Screwfix Select

    Ballpark, 6mm2 SWA is good for 32A on a 25m run. I'd not like to have to terminate 16mm2 cable. Earth arrangements also need due consideration as does termination at both ends and other things that I don't know about.

    Pay for a decent Spark to advise, that's what you pay them for...I'm just some schmuck on an Internet forum.
  11. unphased

    unphased Screwfix Select

    Ball Park is another guess. Work it out, its easy enough.
  12. JP.

    JP. Screwfix Select

    10mm seems a nice size for the average shed in an average garden, it allows a modicum of headroom. Wouldn't go below 10mm myself, and of course if 16mm is indicated do be it..but it's not used much for sheds let's face facts.
  13. Comlec

    Comlec Screwfix Select

    Who needs 15kW in the "average" shed?
  14. JP.

    JP. Screwfix Select

    Dunno really Mr C..10mm is a nice size though..you know people might add extra stuff on in the future, although must say this is not classed as ''future proofing'' a ridiculous term if I may say so.
  15. Bazza-spark

    Bazza-spark Screwfix Select

    I am about to install 70m of 16 mm to feed a screw compactor in a factory requiring a 63 amp D rated (motor) supply. Must be a hell of a shed.

    Kind regards
    Dean DeLuca likes this.
  16. Bazza

    Bazza Screwfix Select

    Ooh look. JP is back:):)
  17. JP.

    JP. Screwfix Select

    Lol..ow u doing Bazz?
  18. Bazza

    Bazza Screwfix Select

    Not so bad. Xmas decs down. Winter draws on, etc.
    How about you?

    CJASENG Member

    As unphased said, calc it out. Think about the total watts your devices will be pulling (say 3kw for heater and 1.5kw for grinder + lights at 100W + tv @ 300W - you'll be drawing about 21.5 Amps) and the distance of wire and voltage drop. There's online calculators to help. - standard 2.5mm T+E will take 27 Amps (6kW) and have a small voltage drop over 6m though - That's what I'd use.
  20. Hans_25

    Hans_25 Screwfix Select

    T&E going to a shed is totally the wrong type of cable is it not? Its either going to be buried in the ground or across the ground, or across a roof.

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