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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

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    The whole of the new installation needs testing and whoever does that testing can test the rod with the same tester, assuming that you need a rod.


    Andy Betteridge
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    Pretty and functional.


    https://www.eliteprecast.co.uk/service-protection/concrete-cable-protection-covers/?gclid=EAIaIQobChMInqmSztH76AIVAuDtCh3VPg6eEAAYAiAAEgJhmfD_BwE



    Z.
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    Wolfie100:

    Thanks all for replies so far. I like the idea of a hard slab like material above the cable, do you think my BC employed inspector will? I have seen that you can still buy cable tiles, just quite expensive. I do believe 300mm to be within spade/fork depth but agree that a piece of robust slab with warning tape above should reduce risk to almost insignificant. The option of going around the obstruction to avoid areas that may be dug in the future is extremely difficult if not impossible. 




    Why not just visit your local steel stockist and buy some large diameter galvanised pipe for the S.W.A. to run through if it is not buried sufficiently deeply to prevent future possible damage?

    Also, perhaps it would be wise to pay an experienced qualified electrician for professional advice and help to prevent future problems and expense.


    Z.

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    Wolfie100:

    . . .  I like the idea of a hard slab like material above the cable, do you think my BC employed inspector will? I have seen that you can still buy cable tiles, just quite expensive. I do believe 300mm to be within spade/fork depth but agree that a piece of robust slab with warning tape above should reduce risk to almost insignificant. . . 




    Two suggestions here for you. Firstly, draw a plan of the area and Mark your new cable route on the plan. Secondly, for a cover, you could use paving slabs cut in half (or buy some narrow ones). You won’t stop everyone digging through it in the future, but with a paving slab, you will hopefully make people wonder what is there and investigate a bit more carefully. You could use some PVC ducting underneath the slabs if you like, which could make pulling in a new piece later on easier. Don’t be tempted with a metal pipe - it needs to be fairly obvious what is in it. Metal may well get mistaken for an old water pipe and someone just cut through it with a Stihl Saw. At least with plastic, if it’s contents are unknown it can be carefully opened to see what is inside. 


    Regards,


    Alan. 

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     Don’t be tempted with a metal pipe - it needs to be fairly obvious what is in it. Metal may well get mistaken for an old water pipe and someone just cut through it with a Stihl Saw. At least with plastic, if it’s contents are unknown it can be carefully opened to see what is inside. 


     



     




    Who in their right mind would cut through an underground metal pipe if they do not know what it is for? It may contain gas. Anyway if they do and no water comes out that will eliminate that possibility. Hopefully the digger will come across the warning tape before they decide to operate the A.D.S. of the live S.W.A. cable by cutting it through. I normally erect warning notices on small posts or onto nearby buildings warning of a buried cable.


    Z.

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    Thirty years when I worked on new housing sites I sat and had lunch with the two water board guys who cut a hole in a oil pipeline that’s part of the national distribution system, because they mistook it for the water pipe. They said it was very impressive when the Military Police arrived by helicopter fully armed to take charge of the situation.


    ?
  • 0
    I also worked for a builder who had to stop the ground workers trying to smash a big lump of cast iron out of the way, not realising it was the Elan Valley Aqueduct.


    As has been said in the past, don’t underestimate the apparent level of stupidity some people manage to reach.
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    It is worth mentioning that there is a standard for plastic ducting to determine what is in it. The most often used colours are: 


    Black - LV Electricity

    Yellow - Gas

    Blue - Water

    Purple - Motorway Communications

    Grey - Telecommunications

    Green - CCTV, Cable TV, Fibre Optics

    Orange - Street Lighting, Traffic Signals


    Regards,


    Alan.
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    There used to be a small water works about half a mile from where we live, it eventually became an industrial water supplier to factories near Queensferry (Flintshire) until the 1980's. Perhaps just as well it was industrial water, since feeding into it was the outfall from Wrexham - Bidston railway track drain. The site was eventually sold for housing, but prior to this a plot of land about half a mile towards Queensfarry was sold with outline planning consent. The owner of this site was not too keen on some valve gear sticking up out of the ground in what would be the frontage of his planned property.  I looked one day and it had gone.  Cut through and disposed of one of the valves between the water works and the factories. Luckily not in use.  Also running through the old waterworks site is a 27 inch asbestos-cement water main connecting a waterworks (potable water) to a distribution reservoir. Luckily the house builders manged to not put a JCB bucket through it!  For good measure, the other side of the hedge is the Shell Anglesea - Stanlow Refinery oil pipeline, now decommissioned for oil and in use for HP gas.

    Clive
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    Alan Capon:

    It is worth mentioning that there is a standard for plastic ducting to determine what is in it. The most often used colours are: 


    Black - LV Electricity

    Yellow - Gas

    Blue - Water

    Purple - Motorway Communications

    Grey - Telecommunications

    Green - CCTV, Cable TV, Fibre Optics

    Orange - Street Lighting, Traffic Signals



    You forgot brown, which is supposed to resemble the terracotta pipes of old. We all know what's in it. ?

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