Cable voltage loss

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  • Maxxarcade
    Badcaps Veteran
    • Jul 2006
    • 973
    #1

    Cable voltage loss

    I am installing a CCTV system with 4 cameras, which will be run from the computer's PSU. The siamese RG-59 cables for the cameras have 18 guage wires for the 12v dc, and I was wondering how much voltage drop I would likely have on 20-50 feet of wire if the cameras draw 400ma.

    Should I use an inline fuse for each wire run, or will the PSU shut down if a short occurs at the far end of the cable? I figured it might melt the wires and start a fire if there is enough resistance in the wire
    Tags: None
    • PeteS in CA
      Badcaps Legend
      • Aug 2005
      • 3581
      • USA, Unsure of Planet
      #2
      Re: Cable voltage loss

      Using the wire table here, I figure your voltage drop will be ~.1V-.25V. Damage due to a short will depend on your P/S's current limit (or power limit) point. AWG #18 should handle 10A-12A without getting too hot, maybe more.
      PeteS in CA

      Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
      ****************************
      To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
      ****************************

        Comment

        • MixMasta
          Senior Member
          • Feb 2006
          • 142
          • USA
          #3
          Re: Cable voltage loss

          I hate to say it, but the Antec power supplies with the external 4 pin molex power connector would be nice for something like this...

            Comment

            • Maxxarcade
              Badcaps Veteran
              • Jul 2006
              • 973
              #4
              Re: Cable voltage loss

              Looks like I'm good to go with the new system.

              Got the 8 channel DVR card installed, and I'm going to make a 12v dc bus on the back of the case using a 16 terminal barrier strip. This will give me enough room for 8 camera dc outputs, individually fused at 750ma or so.

              The poor old Athlon 1400 gets brought to it's knees when using all 8 inputs at anything more than 5 frames per second each I'm gonna see if I can get my hands on an Athlon XP 2100+ Palomino for the old Shuttle AK31 motherboard.

              Also thought it was crazy when I saw all the shared IRQ's on the BIOS list... The DVR card adds 16 devices Then there is the LAN, Video, USB, IDE, and a couple other things. Every single IRQ has at least 2 or 3 things on it. Thankfully Linux doesn't care too much.

              In fact, this is the third motherboard and second DVR card I've had in this system, and I haven't even had to repair or re-install the OS

                Comment

                • shadow
                  Badcaps Veteran
                  • Feb 2007
                  • 732
                  • Australia
                  #5
                  Re: Cable voltage loss

                  Originally posted by Maxxarcade
                  In fact, this is the third motherboard and second DVR card I've had in this system, and I haven't even had to repair or re-install the OS
                  That is pretty impressive!!

                    Comment

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