Type of cable to run to workshop.

Discussion in 'Electricians' Talk' started by AshRich, Sep 3, 2020.

  1. AshRich

    AshRich New Member


    Sorry, I know this question comes up a lot but I can't find anything that answers my particular problem. As I the distance and power consumption

    My workshop (to be) is around 60/70m from my house/consumer unit. I want it to be future proof..ie, welders/compressors. I will be getting a spark to actually do the work but I want to get a head start with the run..so I would like to know what cable to use... preferably It will be buried.

    Thanks very much!
  2. I would suggest you talk this over with your electrician before you do any spade work so the trench is where he or she needs it and not where you think it should go, or you dig out far to shallow and have to go in again :)
  3. AshRich

    AshRich New Member

    Thanks, Tuxornot!

    I'd rather just have an answer to the question!
  4. unphased

    unphased Screwfix Select

    Demanding answers to your 'problem' is not the way to go about it. Its not a problem at all. Its very easy for an electrician. Quite frankly I don't know what people mean by future proof either. Its a stupid term. How can anybody prove anything about the future? Good luck.
  5. Comlec

    Comlec Screwfix Select

    #AshRich you could contact your local DNO and ask for a new 3 phase supply to be installed - this should give you all the "future proofing" you need.
    You can find your DNO here
    Hans_25 likes this.
  6. You want a head start with the run, preferably buried....
    That's a few times that phrase has appeared recently, I don't have a scoobies why, lt must be this weeks trend, my crystal ball must be playing up, missing the trend, wont allow me to see a theoretical cable run over a strangers land........:rolleyes:
  7. AshRich

    AshRich New Member

    I asked a question. A pretty simple question according to you..but instead I'm getting directed to my electrician. What is the point in a forum that you can't ask a question on? There are various reasons that I want to get the cable before speaking to my electrician which I don't have to go into...yes, I agree it is a stuid term but I also told you what I wanted it to supply so it's hardly hard to figure out..
  8. nigel willson

    nigel willson Screwfix Select

    185 mm2 4 core xlpe. Pair cores up . TT at workshop end. Bury at 600mm
    Dx80 and Bazza like this.
  9. Peterdevon

    Peterdevon Screwfix Select

  10. Run a twinwall duct with a draw rope in it, buried 18" deep and come up at the point you want the DB in the workshop. When you have built the workshop the Electrician can then work out swa size and pull it in.
    nigel willson likes this.
  11. unphased

    unphased Screwfix Select

    "... I will be getting a spark to actually do the work ..."

    It is ridiculous to come on a forum and get advice when the spark you hire is going to be the one who does the work, designs it, calculates the cable size. Just ask him. We cant design it for you. There are too many options to give answers anyway. There are literally hundreds of power to garage/shed/summerhouse questions on this forum.
  12. Bazza-spark

    Bazza-spark Screwfix Select

    You asked you question on the forum, and you received an answer on the forum. I would call that a success.

    The fact it wasn't the answer you wished for is your problem and there are various reasons that you got that answer, "that I won't go into."

    If it isn't hard to figure it out then crack on fella!
  13. rogerk101

    rogerk101 Screwfix Select

    When I converted my garage into a granny flat, I called my spark and asked him for his guidance on the cable that I was going to need. I was already digging the trench for taking water down there and wanted to use the trench for the cable and the ethernet at the same time. Given that I wanted to be able to use a lot of power for electric heating, instant hot water heating, induction hob and oven, and I didn't want a huge voltage drop, we agreed that we might as well run 35m of 25mm2 two core SWA and use a TT earthing arrangement (earthing rod at the granny flat). I could have 'got away with' using 16mm2 cable but for the relatively small difference in price between 16mm2 SWA and 25mm2 SWA, I am now a whole lot more 'future proof'.
    Your run is twice as long as mine, so I would recommend using 25mm2 in your case as well. You certainly don't want to have to dig it all up and change a 16mm2 cable to a 25mm2 cable, as the price difference between the two cable types is less than the price of digging it all up again.
  14. 70 meters is a fair run, welders and compressors are a big load, the cable required will be calculated on that so will be big and that's one hell of a pull if you dig and lay ducting, your going to need big arms and after digging that trench as well, that's if its in the right place, your going to look dam silly if your appointed electrician decides its in the wrong place, going the wrong way or decides the proposed load may require a totally new supply installing.

    But if you want to dig then dig but don't get all weepy when it all goes wrong.

    Now if you where just changing a light fitting or something simple then you would get as much help and advice as you can handle, I personally don't know you but it would be a bit mean to let you go ahead and faff up a big job without offering modicum of advice.

  15. unphased

    unphased Screwfix Select

    There will be dozens of electricians wanting this job. It costs nothing to invite a couple round to have a look at it properly and suggest what would be best. That's the best answer I can give you. Everything on the forum would be pure guess work. We don't know what the access is like to the job, where the supply is located, what the earthing system is, what the ground looks like, (hard paved, concrete, soft earth?), what is required for the connection to start the supply off. There is a hell of a lot more to a job like this than knowing what cable size is needed. 70 odd metres of 25mm2 3-core is mighty heavy. May need a forklift to drop it off and then roll it to the start point. Then how easy or difficult is it to run it the rest of the way?
    nigel willson likes this.
  16. Hans_25

    Hans_25 Screwfix Select

    Whatever people say on this forum...you're going to need a bigger cable :D
  17. AshRich

    AshRich New Member


    Thank you for your replies.

    I will get some someone over. I am in favour of getting someone to look at it. I did however just want to look at getting the cable which was my original query. I'm a ship engineer and work with 3∅ 440 but unsurprisingly have never had the need to run a 70m cable to a workshop. Just because someone asks a question about something, it doesn't make them completely clueless.
  18. nigel willson

    nigel willson Screwfix Select

    I’ve already said 185 4core
  19. Bazza-spark

    Bazza-spark Screwfix Select

    This all assumes that your main incomer will take the extra loading.
  20. sparko69

    sparko69 Screwfix Select

    He's just answered your question with good advice.
    If you want to know something specific just ask a specific question... for example..'what size cable do I need" or will 1.0mm be ok for my welder"

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