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Cable for garage and workshop

Discussion in 'Electrics UK' started by Darren9571, 8 May 2021.

  1. Darren9571

    Darren9571

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    Hi
    I have reviewed some previous posts but I am not sure of the size of SWA cable to use for a garage and workshop. I am only planning to put the cable under the floor before some laminate gets laid - I am yet to get planning permission for the garage - but thought I would save an awkward job later accessing the consumer unit.

    The run from the consumer unit will be 14m with most of that under the house and approx 3m underground. The garage/workshop will be running some big tools and ultimately there may be a car charger, so I am happy to over-engineer now just in case and providing that doesn't cause any issues. I thought 6mm or 10mm? Is there anything I need to consider about the cable?

    Thanks
     
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  3. AndyPRK

    AndyPRK

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    people often say there is little cost difference between 6 and 10mm ?
    may as well use 10
     
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  4. flameport

    flameport

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    10mm² 3 core will cover most purposes.
     
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  5. ericmark

    ericmark

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    As @AndyPRK says, but some car chargers need to monitor the power used by rest of house and adjust what charge goes to car so as not cause the DNO fuse to fail, I don't fit electric car chargers, so maybe some one else can advise how the charge monitors total use and if any cables required.
     
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  6. flameport

    flameport

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    Power monitoring can be wired, but plenty are wireless so no additional cables required.
     
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  7. bernardgreen

    bernardgreen

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    Install two ducts, one for the SWA to be pulled through and the second one for any other cables such as data, phone, alarm and car charger control cables.

    If the car charger so monitor consumption in the house and alters the charging rate then maybe a separate SWA cable supplying the car charger with the controlled charging current would make life easier.
     
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  8. AndyPRK

    AndyPRK

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    you don't need 2 swa for car charger
     
  9. AndyPRK

    AndyPRK

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    maybe of interest

     
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  11. bernardgreen

    bernardgreen

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    Very interesting , why is an Earth conductor being switched by 3--4 in that Ktec25 contactor
    upload_2021-5-8_14-56-50.png
     
  12. JohnW2

    JohnW2

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    I can think of reasons why one might want to switch an 'earth' conductor, but I don't think that BVS7671 would ever see eye-to-eye with such a practice, would it?

    Kind Regards, John
     
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  13. AndyPRK

    AndyPRK

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    I think there is a worry that the electrical installation earth, isn't the same potential as the ground by the car. And under fault condtions isolates every conductor
     
  14. flameport

    flameport

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    722.411.4.1.iv.png

    CPC is disconnected as that device is designed to comply with 722.411.4.1.iv as above.
    As installed in the video it will only work if the armour of the cable hasn't been connected to anything at the charger end. If the armour is connected at both ends, the CPC is permanently connected via the metal case of the device which will bypass the contactor.

    Even if installed properly, those devices only detect some instances of open PEN conductors. They are not suitable for use as safety devices, they don't comply with the LVD, and should not be available for sale.

    BS7671 should not include descriptions of such things either, whether they are suitable for use or not.

    The whole of section 722 in BS7671 needs to be completely rewritten. As it is, an installation could comply with every detail of it, and yet still be unsafe.
     
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  15. AndyPRK

    AndyPRK

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    At 4 mins they mention it I think

     
    Last edited: 8 May 2021
  16. JohnW2

    JohnW2

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    Interesting. I hadn't noticed (or remembered!) that and, in particular, not the reference to 543.3.3.101(ii), which says ...
    Do I take it that a device such as the one shown in that video would satisfy that requirement?

    Kind Regards, John
     
  17. flameport

    flameport

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    Very doubtful, it's an off the shelf cheapo contactor available anywhere.
    Proper specifications for it could not be found, including from the 'manufacturer' of the contactor.
     
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