Coax for Analog Cameras

What you need to know about coax cables!

Coax cables can look the same but are they?   Heck NO! This subject can be a bit confusing but it is very important when installing an analog type CCTV system. Coax (short for coaxial) cable consists of an outer jacket, a braided bare wire shield under than, then a plastic insulator (called the dielectric) and finally, one bare center conductor.

The most common cable type used for CCTV is RG-59/U. But to start with the confusion, there are many types of RG-59/U. One is correct and the rest will not work properly. So how do you know which is the right kind? Strip off a piece of the outer jacket and look at the braided shield.   The correct cable will have a very tightly woven braided shield made with copper. It will have the color of a shiny penny. If you strip off the jacket and you see a loose braid made with aluminum conductors and under that, the dielectric is wrapped with aluminum foil, that is cable TV wire and is the wrong coax cable for CCTV use. At a glance they look the same, but in reality will create havoc with a standard composite baseband video signal.   Because CATV (cable TV cable) uses aluminum instead of the vastly more expensive copper material, CATV cable is significantly cheaper. People with think they are getting a bargain until they find out it is the wrong cable ( and the tears begin to flow after realizing that you already installed it in conduit or through the ceiling)!   Don’t make that mistake!   Ask for “RG-59 with a 95% copper braided shield”.

A video signal traveling over the proper RG-59/U coax cable is good for 750’. Will it stop working at 751’?   No, but the whites in the picture will get progressively more gray and your picture will lose contrast overall the further you go.

Need to go more than 750’? Then you should use one of the following:

* RG-6 coax (with same shield) – RG-6 is good for 1500’ of linear distance before signal degradation. It has a larger diameter and a larger center conductor (18 gage instead of 22 gage). This cable requires different BNC connectors to fit the larger diameter.

* BALUN transceivers with UTP unshielded twisted pair cable – Often called “poor man’s fiber”, this setup can go 8000’ or more depending on the BALUNs (slang for balanced – unbalanced) used.   More on this topic later.

* Fiber Optics – great for large distances (miles) depending on the type of fiber and the transceivers used.   Expensive but worth it.

Siamese Cable is a great invention and consists of (1) RG-59/U and (2) 18 gage conductors to carry the power for the camera in the same assembly.   This is very convenient for the person doing the installation and is highly recommended. Buy bulk Siamese in 500’ and 1000’ spools and cut your cable to the length as needed. Putting the connectors on the end is not as hard as you may think. We give you specific instructions on how to do this properly. No special crimp tools are required if you use our “twist on” BNC connectors.

Other types of cables available:

Smaller diameter coax and Siamese cables are hit or miss. These cables are more flexible, thinner and often come with factory installed BNC connectors at each end. Will you see a picture – yes. But what about the quality? Generally speaking, the thinner the cable, the less distance can be run and the potential for electrical or magnetic interference goes up.   10 years ago, we sold a very thin pre-made Siamese cable that was very problematic. Even short runs of 25 or 50’ would be plagued with all kinds of interference usually in the form of jagged lines or herringbone patterns of lines on the screen. The newer cable is thicker and better overall but statistically, has a one in six chance of picking up interference from a multitude of sources in a typical environment (motors, florescent lights, high frequency sources, radio waves, microwaves, poor grounding etc.). I won’t go as far as to say don’t use it, but use caution and stay away form potential sources of interference. I would hate to say I told you so.

Fake RG-59/U – There has been a flood of RG-59/U cable from China lately that does not contain solid copper shield conductors or a solid center conductor. Instead it is “CCS” – or copper coated steel. Yes, they take cheap steel conductors a fuse a small amount of copper to the surface and call it coax. Don’t buy it no matter how cheap it is – period!

It is surprising that I find quite a few licensed electricians that don’t know any of this. Many so called “installers” keep CATV coax in their truck because it can be 60% or 70% cheaper than the proper coax. Then they wonder why the colors are all funky on the screen and there are multiple fuzzy ghost images creating a poor image quality. Maybe they should read this too!

Thanks for reading – leave a comment if you like. More to come in the future. Pro Security Warehouse thanks you for your business.

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Author: dlwyatt1

dlwyatt1 is a 35 year industry professional with a degree in low voltage systems engineering. He has designed multi-million dollar projects for fortune 100 companies and founded Pro Security Warehouse and Integrated Security Solutions 20 years ago.

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