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DIY domestic wiring to outbuildings

Former Community Member
Former Community Member
Hello, I am new to the forums and would like to introduce myself. In the past I have undertaken a lot of domestic wiring as a DIYer. Most of this predated the Part P requirements. However, in 2013 I undertook a fairly major wiring project at my home that included two new consumer units and half a dozen or so circuits. I did this under building control and they arranged inspection and testing. I secured a full set of certificates to underpin my work. I am about to go through the same process to add in two outbuildings to my set up. I have submitted a building notice and am awaiting to hear from Building Control re appointment of a firm to undertake inspection and testing.

Whilst I gather most DIY work scares many of you you, worth pointing out that whilst I am not any form of electrical Engineer, I do have (from many years ago) a HND in Mechanical and Production Engineering and a B Eng (Hons) in Engineering Technology. Both of these included a significant element of electrical technology and electronics. I have also worked in engineering (aerospace) for much of of my early career and still work in a STEM environment. Further,  intend to do a short course on the latest regulations and may also undertake a C&G course on testing and inspection to possibly get to a point where I can register with one of the governing bodies.

I have come to this forum as I am designing my changes and preparing for the first fix. i have been seeking guidance on the internet and from the regulations themselves. I find the regulations open to many interpretations and the advice on many forums to be wildly different. I really want to get this installation right and will have many questions, most requiring practical experience that I simply do not have. I believe this forum will be able to guide me in the right direction when I need it.


My first question relates to burial of SWA. I had a digger in last week to put in a series of trenches for cables. I intend to do all of the external wiring in SWA and in an ideal world would have buried it at 600mm. However, I have places in the garden where it is not possible to get that deep. For an example, under one lawn I have an underground structure that limits the trench depth to 300mm. What would be a appropriate method for installing SWA at this depth? Do I need to add something to prevent a spade/fork penetrating the cable, if so, what would you recommend? I also need to watch my budget here so looking for cost effective views if possible.


There will be further questions. Thank you.


regards


  • Alan Capon:




    davezawadi:

    This is going a little crazy. . . 




    I agree.Either direct bury it, or put it in a black plastic duct. Simple. 


    Regards,


    Alan. 


     




    Do I sense that that implies a definite no, no to an overhead supply cable then?


    Q. How many electricians does it take to design an underground cable route and method of installation?


    Z.

  • One, the one who asks relevant questions ?


    There are ready made Precast concrete cable covers  which obviously come at a cost, a few footway kerbs with cable marker tape along the top of it would serve the same purpose.


    Andy Betteridge 


  • Sparkingchip:

    Going to the extreme you could have one of these in your front garden 



    Google Earth Link
    https://earth.app.goo.gl/uADkJz

    #googleearth




    That’s the Dudley No.2 canal under the front garden, so mind how you knock that long earth rod in, assuming you need one.


    Andy Betteridge 


  • Sparkingchip:

    One, the one who asks relevant questions ?


    There are ready made Precast concrete cable covers  which obviously come at a cost, a few footway kerbs with cable marker tape along the top of it would serve the same purpose.


    Andy Betteridge 

     





  • Direct bury, warning tape, no problem.
  • Seconded - Design by committee and you end up with a SHAMBLES.

    Get it buried and have done.
  • Get what buried?


    Has anyone asked what these out buildings will be used, has anyone determined the maximum demand, has anyone actually determined the means of earthing required for the new part of the installation?


    Those and numerous other questions need to be answered before the type and size of cable can be determined. There’s lots to do before ordering the cable, let alone burying it.


     Andy Betteridge

  • Sparkingchip:

    Get what buried?


    Has anyone asked what these out buildings will be used, has anyone determined the maximum demand, has anyone actually determined the means of earthing required for the new part of the installation?


    Those and numerous other questions need to be answered before the type and size of cable can be determined. There’s lots to do before ordering the cable, let alone burying it.




    The original question was about burying SWA - things like depth, marking and protection. I think that the consensus is to bury direct in the ground and that 300mm will be sufficient.


    We were also told that more questions might follow. I hope that we did well enough and let's answer what followed!

  • ?


    and went off into the realms of buying a loop tester on EBay to test an earth rod to avoid a £400 re-inspection fee because chalk might not provide a good earth.


    Perhaps deciding what you want to achieve along with how and why would be the best approach.


    Andy Betteridge 


  • Is this going to be living accommodation with a potable water supply, if so is a new plastic water pipe going to be dug in a a depth of 300 mm or is there already already an existing water supply, if so is it a metal supply pipe or plastic and what depth is it buried at?


    Andy Betteridge