Surge arrestors

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  • Isetech
    Platinum Member

    • Mar 2022
    • 2274

    #1

    Surge arrestors

    If you install a T2 surge arrestor in a domestic property, do you connect it directly after the main switch, using a 16 mm wire and no fuse or,

    do you install a 32 amp mcb and wire it with 4 mm wire?
    Comments are my opinion, unless regulations are attached to support the comment. This is social media, not a court room.
  • GCE
    Platinum Member

    • Jun 2017
    • 1473

    #2
    Originally posted by Isetech
    If you install a T2 surge arrestor in a domestic property, do you connect it directly after the main switch, using a 16 mm wire and no fuse or,

    do you install a 32 amp mcb and wire it with 4 mm wire?
    Normally a surge arrestor has 125Amp protection rating requirement .Some are different.

    If it was 125Amp rating and my main switch is 80Amp protection , I would leave it at full rating.

    If you stick a 32 Amp C/Breaker in it may trip on a surge that it is trying to clamp and then letting the rest of the surges through which kind of defeats the object.
    I would rather let the surge arrestor take the surge to earth and if it is a big surge trip the 80Amp supply - That way I ensure the client is disconnected from any further surges .

    Comment

    • Isetech
      Platinum Member

      • Mar 2022
      • 2274

      #3
      Originally posted by GCE
      Normally a surge arrestor has 125Amp protection rating requirement .Some are different.

      If it was 125Amp rating and my main switch is 80Amp protection , I would leave it at full rating.

      If you stick a 32 Amp C/Breaker in it may trip on a surge that it is trying to clamp and then letting the rest of the surges through which kind of defeats the object.
      I would rather let the surge arrestor take the surge to earth and if it is a big surge trip the 80Amp supply - That way I ensure the client is disconnected from any further surges .
      The big unit we install in the factories have 125 amp fuses and wired accordingly.

      I have decided to mount the unit next to the main switch and using the busbar at the top to feed the L of the surge arrestor which will have a 16 mm supply cable, which reminds me I must check the main switch is not identified line and load, because the line will be in the bottom. I will also fit a tag on the main cable identifying line and load.

      I am using a little T2 10 ka CBI unit.

      I am told the surge arrestor will not carry any load it is a transient over voltage protective device.
      Comments are my opinion, unless regulations are attached to support the comment. This is social media, not a court room.

      Comment

      • Isetech
        Platinum Member

        • Mar 2022
        • 2274

        #4
        Comments are my opinion, unless regulations are attached to support the comment. This is social media, not a court room.

        Comment

        • Isetech
          Platinum Member

          • Mar 2022
          • 2274

          #5
          This is another topic which we should discuss in a lot more detail. I normally contact the specialist in JHB, but he has retired and only works as a consultant now.
          Comments are my opinion, unless regulations are attached to support the comment. This is social media, not a court room.

          Comment

          • Isetech
            Platinum Member

            • Mar 2022
            • 2274

            #6
            The manufacturer indicated that no circuit breaker is required and a 16 mm wire connected to the top of the surge arrester and a smaller wire for the earth (no size indicated , so we will use a 6mm) would be the preferable way to wire it. Than k goodness I have a busbar on the top of the breakers which are not on earth leakage, so installing a 10 or 16 mm bridge across the top should be fine. The supply breaker is 60 amps.

            I think it might be batter to get it in writing.
            Comments are my opinion, unless regulations are attached to support the comment. This is social media, not a court room.

            Comment

            • Justloadit
              Diamond Member

              • Nov 2010
              • 3518

              #7
              Originally posted by Isetech
              The manufacturer indicated that no circuit breaker is required and a 16 mm wire connected to the top of the surge arrester and a smaller wire for the earth (no size indicated , so we will use a 6mm) would be the preferable way to wire it. Than k goodness I have a busbar on the top of the breakers which are not on earth leakage, so installing a 10 or 16 mm bridge across the top should be fine. The supply breaker is 60 amps.

              I think it might be batter to get it in writing.
              What qualifications does the person have who passed this information to you?
              The earth wire is one of the key elements in the operation of a surge arrester.
              Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
              Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

              Comment

              • Isetech
                Platinum Member

                • Mar 2022
                • 2274

                #8
                Originally posted by Justloadit
                What qualifications does the person have who passed this information to you?
                The earth wire is one of the key elements in the operation of a surge arrester.
                I suppose it is like asking the counter salesman at the wholesaler what size wire you need to connect a 7.5 kw motor.
                Last edited by Isetech; 18-Jun-22, 08:37 AM.
                Comments are my opinion, unless regulations are attached to support the comment. This is social media, not a court room.

                Comment

                • Isetech
                  Platinum Member

                  • Mar 2022
                  • 2274

                  #9
                  Would you install a surge arrestor at the main DB and the essential supply sub DB (after the inverter)?

                  I am wondering if it would be necessary after the inverter, considering the inverter offers a pure sine wave and should have some form protection built in.

                  It is a requirement to install DC surge protection in a combiner box for the solar power.
                  Comments are my opinion, unless regulations are attached to support the comment. This is social media, not a court room.

                  Comment

                  • Dylboy
                    Gold Member

                    • Jun 2020
                    • 777

                    #10
                    I would say no as you say the inverter does all that

                    Sent from my CPH2197 using Tapatalk

                    Comment

                    • Dylboy
                      Gold Member

                      • Jun 2020
                      • 777

                      #11
                      Another question if I may:

                      They say the Type 1 must be installed at the main switch which I think would be near the MP by the supplier connection.

                      How ever that is not always possible in those spider boxes.

                      Can the Type 1 be installed with the Type 2 next to each other in the main DB of the house?

                      I know there is a combined 1 and 2 but those are extremely expensive.

                      Sent from my CPH2197 using Tapatalk

                      Comment

                      • Andrew_van_Zyl
                        Bronze Member

                        • Mar 2022
                        • 131

                        #12
                        Originally posted by Isetech
                        If you install a T2 surge arrestor in a domestic property, do you connect it directly after the main switch, using a 16 mm wire and no fuse or,

                        do you install a 32 amp mcb and wire it with 4 mm wire?

                        Comment

                        • GCE
                          Platinum Member

                          • Jun 2017
                          • 1473

                          #13
                          Originally posted by Dylboy
                          Another question if I may:

                          They say the Type 1 must be installed at the main switch which I think would be near the MP by the supplier connection.

                          How ever that is not always possible in those spider boxes.

                          Can the Type 1 be installed with the Type 2 next to each other in the main DB of the house?

                          I know there is a combined 1 and 2 but those are extremely expensive.

                          Sent from my CPH2197 using Tapatalk
                          You can mount the 2 next to each other , type 1 first
                          It is best to use a combination type when installing together.

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