Going Stranded for your IP camera? Make sure you don’t lose your picture
With the increasing popularity of IP cameras and high quality field terminated plugs, there has been a trend to move from solid to stranded conductor cable for horizontal cabling. The use of stranded conductor cabling offers the advantage of increased flexibility when connecting an IP camera with Pan/Tilt functions and removes the need to have a transition point near the camera where the cabling changes from solid to stranded conductor. Instead the cable can be run right up to the camera and terminated with a plug directly onto the camera without the need for a separate wall plate and patch lead saving time and money. Whilst on the surface this may seem like a good idea and an insignificant change, the move to stranded conductor for the horizontal cabling can result in poor or inconsistent system performance under certain conditions.
Within the standards, the transmission requirements for solid and stranded Category cable is for the most part identical with only a few exceptions. One of these, which can have an influence on system design, is that the standards allow for increased insertion loss in a stranded conductor cable when compared to a solid conductor design. The reasoning for this is that both the DC and HF resistance of a stranded conductor are higher than a similarly sized solid conductor and this drives the insertion loss up.
Both the ANSI TIA/EIA 568 and ISO 11801 (on which AS/NZS 3080 is based) permit insertion loss increases of up to 50% on a stranded conductor cable. As a result of this allowance, the distance that a horizontal cable using stranded conductors can run should be de-rated from the nominal 90 metres that we are all familiar with, down to 60 metres. Running distances longer than this puts the system performance at risk due to insufficient signal strength. Furthermore, the temperature variation and long term stability of the insertion loss in stranded conductor cabling is generally higher than for solid conductor cabling, so whilst a channel using 100% stranded cabling may test satisfactorily when first installed, the increase in insertion loss on days of higher temperatures or over time may go over the system limits resulting in signal or picture loss.
Properly designed systems that take into account the higher insertion loss of stranded versus solid conductor cabling can be installed and can fulfil the customer’s brief, but the uncontrolled substitution of stranded for solid horizontal cabling should be carefully considered, particularly when the channel length is over 60 metres.
So the next time you are considering to change from solid to stranded conductor for your horizontal run to an IP security camera, take into account the higher insertion loss that you can expect in a stranded conductor cable and don’t lose your picture.
For more information on Garland Stranded category cable contact your local sales representative.