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CCTV Cable information

CCTV Power Supply Distance, Cat5 & Siamese Cable Considerations 

Cat5 or Siamese Coax

We experience a number of clients asking about using cat5 cable rather than traditional Siamese coax cable for their camera runs.  Is cat5 heavy¬Ě enough?  Will I be able to transmit video as far as I can with Siamese?  How does the power work with regards to cat5 cabling? 

Is cat5 heavy enough? and similarly, am I be able to transmit video as far as I can with Siamese? 

The short answer is yes, cat5 is heavy enough to transmit video.  In fact, most sources show that the 24AWG (American Wire Gauge) used to make up the cat5 will actually transmit video farther than the RG59 used in the Siamese cable.  One only needs to incorporate an adapter from BNC to unshielded twisted pair (UTP) to make this physical connection work.  Such an adapter in the CCTV business is referred to as a balun, and comes in several different models –  

Wire Gauge and Voltage Drop

For the majority of analogue cameras, Siamese cable is adequate to run both the power and the video.  The most common type of CCTV Siamese cable is a combination of RG59 coax and 18/2 power cable.  RG59 will carry the video signal around 750 ft, so for most runs that will be more than enough.  Power is what will restrict most longer runs.

18/2 cable is two 18 gauge wires.  That is simple enough; if there were four wires it would be called 18/4.  Wire thickness is measured by gauge and the smaller the gauge the thicker the wire.  So, 14 gauge wire will be thicker than 18 or 24 gauge wire. The reason that is important is that a thicker wire will transmit electricity farther that a thinner wire.  Why does this matter?  Because if you have a long run from the power supply and DVR to a camera and there is no way to power the camera locally, you will have to adjust the gauge of the wire to compensate for the voltage drop – View our voltage/amperage quick guide. 

Below we’ve created a chart that will help with planning a long run.  Make sure when calculating that you know the voltage and amperage used by the camera.  Make sure you use the max amps listed on the spec sheet.

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