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aussie auto loom - What Size fusible link do i need?

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    aussie auto loom - What Size fusible link do i need?

    Iv rewired a whole car with a universal loom and have misplaced the fusible link for the power supply to the fuse box.
    anyone able to give me some info on working out what size i need to replace it with.
    The wire is 3mm core running 1.3/1.4m from the battery to the fuse box.

    Iv got it dummied up with a blade fuse at the moment, but wanna get it sorted properly

    (the company i bought the loom from no longer exists so i cant call them to ask - aussie auto looms if anyone know if they have rebranded/named)

    Thanks in advance
    Gene
    Originally posted by Lobster
    Freeze a gearbox and slide it under his front door

    #2
    Anyone? Any auto electricians?
    Originally posted by Lobster
    Freeze a gearbox and slide it under his front door

    Comment


      #3
      3mm or 3mm^2? This has a good gauge calculator

      https://jaydeeautocables.com.au/pages/cable-size-chart

      Bear in mind that this is max amperage. Far better to add up current draw and install a fuse around that amperage so long as it’s less than the max amperage for the cable.
      Chris
      ------
      The new nugget
      I never saw a wild thing sorry for itself. A small bird will drop frozen dead from a bough without ever having felt sorry for itself. - D.H.Lawrence

      Comment


        #4
        Add up all the fuses the will be fed by that wire, add a bit on top and that's your answer.

        Comment


          #5
          Originally posted by tim510 View Post
          Add up all the fuses the will be fed by that wire, add a bit on top and that's your answer.
          So long as this is under the max amperage for the wire.
          Chris
          ------
          The new nugget
          I never saw a wild thing sorry for itself. A small bird will drop frozen dead from a bough without ever having felt sorry for itself. - D.H.Lawrence

          Comment


            #6
            well if it isn't, there are bigger issues. the whole thing has been done wrong.

            Kind of goes without saying.

            Comment


              #7
              Originally posted by takai View Post
              3mm or 3mm^2? This has a good gauge calculator

              https://jaydeeautocables.com.au/pages/cable-size-chart

              Bear in mind that this is max amperage. Far better to add up current draw and install a fuse around that amperage so long as it’s less than the max amperage for the cable.
              Its 3mm diameter. 7.07mm2 core roughly 9-10AWG
              I dont wanna use a fuse, needs to be a fusible link

              online all i can find is "rule of thumb" type stuff mixed between use a fusible link 2 times smaller (eg if its 10 gauge use 12 gauge) and use a fusible link 4 times smaller (eg if its 10 gauge use 14 gauge)
              Nothing based on numbers though
              Originally posted by Lobster
              Freeze a gearbox and slide it under his front door

              Comment


                #8
                Originally posted by tim510 View Post
                well if it isn't, there are bigger issues. the whole thing has been done wrong.

                Kind of goes without saying.
                Should go without saying, but the main feed for the kit I bought a while back was only 14AWG...
                Chris
                ------
                The new nugget
                I never saw a wild thing sorry for itself. A small bird will drop frozen dead from a bough without ever having felt sorry for itself. - D.H.Lawrence

                Comment


                  #9
                  Originally posted by takai View Post

                  Should go without saying, but the main feed for the kit I bought a while back was only 14AWG...
                  yeah the main feed is only 9 on mine which is far too small to run everything, but its also go another one coming from the alt for when the car is running which would pick up the slack
                  i just wanna protect the wire for what its capable of
                  Originally posted by Lobster
                  Freeze a gearbox and slide it under his front door

                  Comment


                    #10
                    Are you trying to use an old school 'fusible link' - ie bit of wire(this used to be a specific type of wire, and shouldnt really just be a bit of undersized wire), or happy to use a plug in type fusible link? https://www.narva.com.au/categories/...ies/fuse_links
                    The sole purpose of a fuse or fusible link should be to protect the cable that comes out of it. So pending on what that is (and its length) - size the link to suit. Adding up all the fuses etc is just wrong, if a system is designed in that way, the main power cable would be massive. There will be an assumption made of the actual required current of the whole car, and then sized up from there.
                    So - as has been covered before - size it to the cable.

                    Comment


                      #11
                      Conversely, if you don't add up current draw of items in the car then you end up like both my old Mini and the old Jag where you would blow the main fuse if you were driving at night in the rain in winter with headlights on and wipers going along with the fan going for the heater.
                      Chris
                      ------
                      The new nugget
                      I never saw a wild thing sorry for itself. A small bird will drop frozen dead from a bough without ever having felt sorry for itself. - D.H.Lawrence

                      Comment


                        #12
                        yeah you are right, its a combination of the two methods.

                        Max power draw and the max load the physical link can take.

                        I just assumed a pre-made loom is designed so physical link is big enough to run everything flat out (because that's what I do).

                        Most OEM cars I've worked on are like this. Big cable to supply the fuse box, with a fuseable link in between.

                        Comment


                          #13
                          Originally posted by vs355 View Post
                          Are you trying to use an old school 'fusible link' - ie bit of wire(this used to be a specific type of wire, and shouldnt really just be a bit of undersized wire), or happy to use a plug in type fusible link? https://www.narva.com.au/categories/...ies/fuse_links
                          The sole purpose of a fuse or fusible link should be to protect the cable that comes out of it. So pending on what that is (and its length) - size the link to suit. Adding up all the fuses etc is just wrong, if a system is designed in that way, the main power cable would be massive. There will be an assumption made of the actual required current of the whole car, and then sized up from there.
                          So - as has been covered before - size it to the cable.
                          yeah im trying to use an oldschool style fuse wire style link. a lot cleaner and hidden. Plug in probably happy to do if they arnt to bulky that way i can keep a few in the glove box for when driving at night in the rain in winter with headlights on and wipers going along with the fan going for the heater ;P

                          but ultimately im just trying to work out how to size the link. as i dont know how to work out the amps fo rthe feed cable base don its size and length.
                          Originally posted by Lobster
                          Freeze a gearbox and slide it under his front door

                          Comment


                            #14
                            The mains in a house are not capable of having every circuit breaker running at their rated current, nor will the main feed to your fuse box.

                            It's distributed load and maximum demand calcs, and the reason there is actual theory behind designing this stuff and component selection. Not saying that's how Aussie auto looms did it, but it's certainly how OEM engineers do it.

                            If you fuse the main cable at the sum of all downstream fuses you'll likely not protect the cable and potentially damage the insulation or worse in the event of a fault.

                            Fuses(able links too) exist only to protect cables down steam. Work out the cables current carrying capacity and size the fuse just under that.

                            Cross sectional area and strand count should be all you need to determine the current carrying capacity of the cable.
                            Jason Broadhurst

                            Someone once asked me if they could use my mower. I said "sure, so long as it doesn't leave my yard"

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