1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Please note - to keep GC running smoothly, from time to time the staff will have to close a long thread and continue it in a new thread. You too can do your bit to help - if you have a long running PM conversation, please terminate the conversation and start a new conversation. For further information, please contact a member of the staff team.
    Dismiss Notice

What size armoured cable for greenhouse electrics?

Discussion in 'Greenhouse Growing' started by Sheps, Apr 21, 2017.

  1. Sheps

    Sheps Gardener

    Joined:
    Mar 30, 2017
    Messages:
    41
    Gender:
    Male
    Location:
    West Yorkshire
    Ratings:
    +63
    Hi everyone,

    I'm going to buy all the bits for my greenhouse electrics in the coming days, so can anyone please tell me what size armoured cable would be best for the job?

    The job will be carried out by a qualified electrician once I have bought all the bits.

    Thanks

    Sheps.
     
  2. Hex_2011

    Hex_2011 Gardener

    Joined:
    Apr 8, 2011
    Messages:
    192
    Gender:
    Male
    Ratings:
    +132
    Cable size will depend on what you plan to run off it and how long the cable is. Cable length affects the voltage drop. This calculator will give you some idea but always best to double check with the sparky before buying
    Voltage Drop Calculator | TLC Electrical
     
    • Like Like x 2
    • Agree Agree x 1
      Last edited: Apr 21, 2017
    • HarryS

      HarryS Eternally Optimistic Gardener

      Joined:
      Aug 28, 2010
      Messages:
      6,761
      Gender:
      Male
      Occupation:
      Retired
      Location:
      Wigan
      Ratings:
      +10,679
      Check with your electrician on the SWA cable size . For the cable , glands , waterproof socket etc etc go to a good electrical factor . This should be cheaper than going to the big sheds. Screwfix prices will be good , but not sure they sell SWA by the metre ?
       
      • Like Like x 1
      • JWK

        JWK Gardener

        Joined:
        Jun 3, 2008
        Messages:
        18,315
        Gender:
        Male
        Location:
        Surrey
        Ratings:
        +16,693
        Personally I'd let the sparky buy everything, they know what they need and saves you having to do the sizing calculation from scratch. Plus they will probably be able to buy it all cheaper from a factor.
         
        • Agree Agree x 3
        • Like Like x 1
        • Scrungee

          Scrungee Well known for it

          Joined:
          Dec 5, 2010
          Messages:
          12,158
          Location:
          Central England on heavy clay soil
          Ratings:
          +18,242
          Do you have a spare way in your consumer unit for this circuit?
           
          • Like Like x 1
          • Sheps

            Sheps Gardener

            Joined:
            Mar 30, 2017
            Messages:
            41
            Gender:
            Male
            Location:
            West Yorkshire
            Ratings:
            +63
            Thanks for the advice, it's appreciated...I think it might be best leaving it to the Sparky :blue thumb:

            Hi Scrungee...yes, I have spare ways in the CU in the house and in the old type fuse box in the garage, I was planning on having the power supply to the greenhouse coming from the garage fuse box, but now that I think about it I might have to have the old fuse box changed out for a new CU before the Sparky will even think about doing the wiring for the greenhouse :yikes:

            Think I might have started running before I could walk on this particular job :redface:
             
            • Agree Agree x 1
            • Scrungee

              Scrungee Well known for it

              Joined:
              Dec 5, 2010
              Messages:
              12,158
              Location:
              Central England on heavy clay soil
              Ratings:
              +18,242
              Are they RCD protected?
               
              • Like Like x 1
              • Sheps

                Sheps Gardener

                Joined:
                Mar 30, 2017
                Messages:
                41
                Gender:
                Male
                Location:
                West Yorkshire
                Ratings:
                +63
                The Consumer Unit in the house is one of the new, 17th edition, metal types and has dual RCD's, with the power supply for the garden / garage running off this on its own MCB.

                So, with that being the case, is the old type fuse box ( pull out plugs with fuse wire ) in the garage protected by RCD? or does this still need replacing with a new one with its own dedicated RCD.
                 
              • Vince

                Vince Not so well known for it.

                Joined:
                Mar 10, 2008
                Messages:
                1,183
                Gender:
                Male
                Occupation:
                Dog Boarding, walking and training
                Location:
                SW Herts / North London
                Ratings:
                +1,366
                Best not say what I do, but it works!:snorky:
                 
                • Like Like x 1
                • Sheps

                  Sheps Gardener

                  Joined:
                  Mar 30, 2017
                  Messages:
                  41
                  Gender:
                  Male
                  Location:
                  West Yorkshire
                  Ratings:
                  +63
                  When first thinking about it I probably had a similar idea, Vince :yikes:...mine was heavy duty rubber pond cable, plug on one end and a waterproof socket on the other, running through some black flexible conduit and into a circuit breaker in the garage :hapfeet:

                  But in the end I thought I better have it done all legal like.
                   
                • ARMANDII

                  ARMANDII ADMINISTRATOR Staff Member

                  Joined:
                  Jan 17, 2011
                  Messages:
                  37,691
                  Gender:
                  Male
                  Occupation:
                  Semi-retired
                  Location:
                  West Cheshire
                  Ratings:
                  +42,308
                  I bought all the electrical gear and armoured cable for installing into my Observatory and carried out all the work fitting it. I'm an ex-RAF Radar Technician and so my certification still stands despite the recent changes in the qualification system. But, even so, I had a friend who is also a qualified working electrician to check my work as it never harms to do so. I'd definitely make sure that the power source is RCD and any sockets you installed are "weather proof" and also RCD.:coffee::snorky:
                   
                  • Like Like x 1
                  • Sheps

                    Sheps Gardener

                    Joined:
                    Mar 30, 2017
                    Messages:
                    41
                    Gender:
                    Male
                    Location:
                    West Yorkshire
                    Ratings:
                    +63
                    Thanks for the advice, Armandii...I'll make sure that RCD's are fitted.
                     
                    • Friendly Friendly x 1
                    • HarryS

                      HarryS Eternally Optimistic Gardener

                      Joined:
                      Aug 28, 2010
                      Messages:
                      6,761
                      Gender:
                      Male
                      Occupation:
                      Retired
                      Location:
                      Wigan
                      Ratings:
                      +10,679
                      For my outside electrics I have RCD protection for each of the three circuits . Last year my new kitchen electrics were fitted and certified by an electrician , we also fitted anew consumer unit.
                      I asked him that with the modern breakers fitted in a CU do I still need RCD protection for my outside electrics ? The answer was not really but it does no harm to have double protection .
                      So do you need RCD protection for outside electrics ?
                       
                      • Like Like x 1
                      • ARMANDII

                        ARMANDII ADMINISTRATOR Staff Member

                        Joined:
                        Jan 17, 2011
                        Messages:
                        37,691
                        Gender:
                        Male
                        Occupation:
                        Semi-retired
                        Location:
                        West Cheshire
                        Ratings:
                        +42,308
                        I think the answer to that, Harry, lies in my left hand where the shape of a male/female connector was burnt to the bones of my fingers and palm of my left hand. Many years ago, while abroad, I was called straight from servicing an aircraft to repair some machines in a Commcen. When getting there I noticed that someone had left a wired connector lying on the floor of a working area. I picked it up only to have it fall apart in my hand.........I still have the scars after all those years and I can still remember the smell of my burning hand. So, you can understand why I trust no one's work but mine and have the greatest respect for electricity.
                        Electricity is not like water or gas. You can't see, smell it, hear it, or taste it.............but you can feel it.
                        You can do electrical work yourself, if unqualified, but you do have to have a professional electrician check and verify your work. That is not as easy as it sounds as most electricians won't verify the work and will want to do it themselves.
                        If the sockets are going to be outside, including in a Green House, then they need, in my opinion, to be doubly safe and going the extra mile to install weather proof RCD sockets is something you won't regret. There is the possibility of other members of the family, over time, going into the Green House and using the sockets so everything has to be doubly safe to give peace of mind.
                        I'm sure the Electrician that Shep will use will do the job to the highest safety level and decide how much he will put in, but I'm also sure the provision of weather proof RCD sockets will meet his approval as an extra safety check. I had my friend check my work as it was a long job and I was also doing several other jobs at the same time and there were several days when I had been working 12 hours on my knees or back to get the jobs done, and that's when you get tired and make mistakes. My friend wondered why I had asked him and I told him about it being a one man job . After inspection my friend grinned and told me I'd put in more safety checks that he might have done when working on a job but approved of them.
                        Are Weather proof RCD sockets necessary?.........the age old scars on my left hand make me nod my head, Harry.:dunno::coffee::snorky:
                         
                        • Like Like x 2
                        • Sheps

                          Sheps Gardener

                          Joined:
                          Mar 30, 2017
                          Messages:
                          41
                          Gender:
                          Male
                          Location:
                          West Yorkshire
                          Ratings:
                          +63
                          I already have one of these in the garden, fastened to the outside of the garage and it has worked spot on for many years.
                          ae235.jpg
                          So, I was thinking 2 of this type in the Greenhouse would be sufficient, giving me enough sockets for a Fan, Heater, Heated Propagator and Radio, but if anyone can recommend a better type, then feel free to comment :)
                           
                          • Like Like x 2
                          • JWK

                            JWK Gardener

                            Joined:
                            Jun 3, 2008
                            Messages:
                            18,315
                            Gender:
                            Male
                            Location:
                            Surrey
                            Ratings:
                            +16,693
                            I don't think you should use a RCD type socket like that if it's already on a circuit coming from a CU with RCD protection.
                             
                            • Like Like x 1
                            • Friendly Friendly x 1
                            • ARMANDII

                              ARMANDII ADMINISTRATOR Staff Member

                              Joined:
                              Jan 17, 2011
                              Messages:
                              37,691
                              Gender:
                              Male
                              Occupation:
                              Semi-retired
                              Location:
                              West Cheshire
                              Ratings:
                              +42,308
                              It only acts as a secondary barrier, JWK, and whether or not a CU has RCD protection is not a problem and in fact it would react a mill-second before the CU RCD.:dunno::snorky:
                               
                              • Like Like x 1
                              • Scrungee

                                Scrungee Well known for it

                                Joined:
                                Dec 5, 2010
                                Messages:
                                12,158
                                Location:
                                Central England on heavy clay soil
                                Ratings:
                                +18,242
                                Which can be an advantage if for some reason you don't want a fault in shed electrics to trip the house CU, but a disadvantage if you have a freezer in there as you will unaware of any power failure in there (unless you have either a wireless alarm or cabled alarm with the cabling laid in same trench as power cable).
                                 
                                • Like Like x 1
                                • ARMANDII

                                  ARMANDII ADMINISTRATOR Staff Member

                                  Joined:
                                  Jan 17, 2011
                                  Messages:
                                  37,691
                                  Gender:
                                  Male
                                  Occupation:
                                  Semi-retired
                                  Location:
                                  West Cheshire
                                  Ratings:
                                  +42,308
                                  Any power sources for domestic appliances should be routed on a separate circuit so that one failure does not affect another.

                                  You're not likely to have a fridge in a Green House, Scrungee:dunno::heehee:, although, granted you might have it in a Garden Shed but, again, they should be on separate circuits.:dunno:
                                   
                                  • Like Like x 1
                                  • Scrungee

                                    Scrungee Well known for it

                                    Joined:
                                    Dec 5, 2010
                                    Messages:
                                    12,158
                                    Location:
                                    Central England on heavy clay soil
                                    Ratings:
                                    +18,242
                                    Replacement of a garage 'fuse box' has been mentioned above, and freezers are commonly located in garages.
                                     
                                    • Like Like x 2

                                    Share This Page