The Pro’s and Con’s of Using Shielded Network Cables

Any products that are powered by electricity, also emit electromagnetic energy in the form of radio frequency emissions, or RF frequency. These signals generally fall in the AM/FM radio range, and can be measured with any RF signal detector. The problem is these frequencies disturb other equipment in the area, causing interference. In video surveillance situations, it could be loss of picture quality in your cameras or monitors. Other devices nearby can also be effected.

In order for these devices to function in an environment, they will have to be Electromagnetic Compatible (EMC), so they do not disturb or disrupt nearby equipment. In order for EMC to work, you have two items, emissions of the RF signals, and immunity from the RF signals. Immunity is the ability of any electronic product to tolerate the introduction of electrical energy from electronic products near by. You should look at both emissions and immunity when setting up a video surveillance network.

The biggest cause of emissions in a network camera deployment would be using unshielded twisted-pair or UTP cables to connect the cameras near RF emissions, instead of using shielded twisted-pair (STP) cables. The difference between the two is that the STP version is a Class B FCC product designed for home use, which will have higher RF emission requirements. The UTP is a Class A FCC rated product with lower emission requirements, meaning higher emission rates that will cause the interference.

The main issue is when you run the UTP in an environment that has other electrical devices like lighting, motors, or other electronic devices that give off RF signals. For example, running a UTP along side or inside a conduit with 12 or 24 volt electrical line to power a light. In this case, you would want to use the STP cable, which will help to block the emissions from the electrical line.

However, when you are just running one cable to one camera and nothing is near it, there is no reason why you can’t use UTP cable, as there is nothing nearby emitting electromagnetic signals. Let’s look at the Pro’s & Cons of STP cables.

The Pro’s of Shielded Twisted-Pair Cable is that it blocks RF emissions so you have less interference problems, resulting in better video quality.

The Con’s are it is more expensive, and less flexible, so installations might be harder & will cost more.

Since you really don’t have to run STP to every network camera, it should not be a huge problem or expense. Unless you see that you have certain camera cable runs that could be an issue with other electronic devices nearby, for the most part, you don’t need to run STP to every camera. Instead, you can install the UTP cables for the rest of your surveillance system, and save the STP for those other areas.

Making sure you are protecting your video signals in areas that have high RF emissions is critical to achieving a successful network camera deployment, so every camera can be seen, and the results recorded for future use.