9 February 2011 Comments Off on Security Camera Cabling

Security Camera Cabling

We are specifically going to be talking about cabling for analog CCTV cameras. This consists of power and video cables for all cameras and data cabling for PTZ cameras which are a breed of their own.
IP camera wiring which we will be discussing in a separate article is mostly accomplished with Ethernet cables with both video and power commonly delivered in the same cable.

All fixed analog cameras need two kinds of cabling to function. Power wire and video cable. You need two types of cabling because your power will come from either a power transformer or a central power supply, and your video will go back to a monitor or some kind of quad processor if you are just viewing it, or a DVR if you are going to record the footage being transmitted. Some people think the power for the cameras will come from the DVR which is not correct.

You have distance limitations that we will talk about in a moment that normally dictate which of the following cables you will want to use.

Power Wire

Power Wire

First we’re going to talk about power wire. Most installations use 18/2 (18 gauge -2 conductor) stranded power wire. Using this gauge you are limited approximately to 150’ for most 12V DC cameras and around 650’ for 24V AC cameras.   If you need to go farther distances you can use a larger gauge wire such as 16/2, or power the camera closer to the camera and run separate video cabling back to where you need to view the video.

Coax Cable

Coax Cable

With video wire you have lots of options. Most installations use coax cable that is either RG59U or RG6U.  Coax cable is made up of a center conductor, normally a white insulator (and sometimes a foil wrap), copper braid, and then an outer vinyl shield for protection. The center conductor and the copper braid is actually what carries the video signal, consider it your + and -.   The white insulator around your center conductor (+) is in place to keep the braid from touching that center conductor.  If those two metals touch it can completely short out the video signal, or even create what we call ground looping.  Ground looping commonly shows up as a nasty black horizontal bar that scrolls from the bottom of the video picture to the top.  So when you are terminating your coax with BNC connectors you want to make sure the braid never touches your center conductor or you’ll be chasing it down later when you have a bad picture or no picture at all.

RG59 coax can be used to transmit video up to around 650’.  RG6 is used on larger runs up to around 1200’ but you have better interference shielding with the RG59 coax because the copper braid is a tighter weave.  You will need different sized connectors depending on which kind of coax you select because the size of the outer jacket is bigger for RG6 as well as the center conductor.

Cat5

Cat5

For longer runs or if you have existing wiring in place you can use Cat5 and baluns to transmit video.  Each camera only needs one pair out of the 4 that are in a typical jacket of Cat5.  So you can run up to 4 cameras on a single Cat5 cable.  Baluns are very small adapter boxes that change the BNC connector for the camera into screw terminals for Cat5.  You will need a pair of these per camera, one on each end of the Cat5.

Non-Powered Balun

Non-Powered Balun

Powered Balun

Powered Balun

There are two kinds of baluns – non- powered and powered.  Non-powered are typically used in the same building and distances less than 700’ to 800’.   Powered Baluns are used if you are going between buildings (you have some surge protection built into the powered boxes) and distances longer than 700’ to 800’.   Something that is nice about Cat5 is the twist in the cable.  It actually gives you built in noise immunity due to the twisting of the wires.  You can transmit upwards of 2000’ over Cat5 with the use of powered baluns.

Siamese Cable

Siamese Cable

Most camera installs use something called Siamese cabling that consists of dual cables joined together, which contain RG59 and 18/2 power wires.  The power wires are normally in their own vinyl shield and can be easily separated prior to termination using a pair or wire cutters to snip the ends of the cabling apart.

Pre-made Cable

Pre-made Cable

Siamese cabling normally comes in two completely different varieties – pre-made cabling and a spool of cable along with a toolkit.  The pre-made cables are very easy to use because they are already pre-terminated for both power and video and just connect on both sides with the use of power leads, but they are normally only made in certain lengths. If you have a 70’ run and the only sizes available are 60’ and 100’ you’re going to have 30’ of extra cable coiled up which can cause its own set of problems.

Spool of Cable

Spool of Cable

You can also custom make your cables using a spool of cable and a toolkit and terminate your cables to the exact right length for a perfect fit and a much cleaner install.  This type does have a bit of a learning curve if you’ve never done it before, and it’s not as simple as running pre-made cables with the connectors already attached.

If you have an electronically adjustable PTZ camera you have to power it closer to the camera with the provided power supply (due to higher amperage requirements) and then you will run video and data back to the monitoring station.  Cat5 is what you will use to transmit data, and again you only need one pair per camera.  You can run video and data for 2 PTZs over one piece of Cat5.  You do not want to run power over Cat5.  The gauge is just too small.

Now you need to pay attention to distances, and guessing sometimes will bite you in the behind.  If you use the wrong cable you will not only have extra man hours to pull the wrong cable out but you will have to scrap that cable, buy new, and then run the new lengths.  Needless to say it is time consuming, frustrating and a money waster. Here are a few examples to help you see what kind of cable you might need to use.

  • Your camera runs at 12V DC and you need to run the cabling 250’. You will use 18/2 power wire and an individual transformer and power the camera close to the camera. Then you will use RG59 coax to run it back to your monitor or DVR.
  • You have 8 cameras that are all 12V DC and you only need to run them 50’-60’. You will use premade Siamese cabling and run everything back to your DVR and central power supply (and you will be able to connect them all to a UPS Battery Back-up).
  • You’ve got a 24V AC PTZ camera that you need to run 900’. You will use 18/2 power with the provided transformer and power the camera at the camera, and then you will use Cat5and powered baluns to run both the video and the data back to your DVR.

The most important thing to remember is to talk to the company you are buying your equipment from.  They should be able to tell you what kind of cabling you need and explain to you why it is better than some of the other options.  A lot
of the time most cabling runs are less than 150’ so you can use what is the easiest/cheapest/or just your personal preference.  And sometimes you need a combination of cable types to achieve the desired install.

Here are a few extra hints to help your installation run smoothly.

  1. Siamese cabling is both RG59 U coax cable and 18/2 power wire and can save time and money if all runs are less than 150’.
  2. Low voltage wire CANNOT be run in the same conduit as 110V power. You will get interference into your camera signal EVERY TIME!
  3. If you are using Cat5 for both video and data for a PTZ camera don’t use it for the power. The gauge is too small to power even the smallest infrared camera and you can burn the wires even though it is low voltage.
  4. LABEL YOUR CABLES. Most people when they install a surveillance system do all of one task, like running the cables, before moving onto the next task, such as hanging cameras.  Knowing which set of cables goes to which camera is invaluable. If all your cameras use 24V AC except one camera, and you hook up that 12V DC camera to 24V – you’ll most likely have the privilege of buying a new camera when you fry the first one.  A couple extra minutes can save you money and a huge amount of time when you connect the system.  Not to mention help you troubleshoot months or years down the road if you have issues.
  5. Don’t pull too hard on the cable. The cable is not indestructible and if you pull too hard you can catch the vinyl on sharp objects inside the wall, ceiling, etc. wherever it is running through and you can strip the cabling without realizing it.  This can create ground looping if you touch the braid to metal in the wall, it can short out cameras, you can even break center conductors inside if a kink gets in the cabling and you pull too hard.  Intermittent video and ground looping can be hard to chase down and diagnose even for the most seasoned installers.  So take your time when you install your camera cables. A little extra time can save you a huge headache in the future.
  6. You want to be as exact as possible on the length of cable you run but still have a little extra (several feet is great).   Too short and you have to use barrel connectors on the video side with extra coax jumpers which decreases the  quality of the video at every joiner.  You don’t want to spend $300 on a camera to be thwarted by a cable that is 2’ too short (every connector loses approximately 3db).    Too long and if you coil up the extra you’ve just made one giant antenna that pulls interference directly into your video signal.
  7. If you have to cross video or data cabling with high voltage (110V) power wires cross it at a 90 degree angle. In most cases it will cancel out the interference you would normally pull into the cabling.  It’s all to do with sine waves between the 1V peak-to-peak video and data signal and that of the power transmission.  Just trust me and make a “T” out of the cable.  You’ll thank me later.
  8. If you are using wire staples to fasten your cable to a surface, make gentle turns and curves. A 90 degree bend will not only break the center conductor, but will attract interference from any nearby electrical or RF noise source (meters, lighting ballasts, pumps, etc).
  9. One last hint on the power wiring for your cameras. Treat each camera like it is polarity sensitive even if it isn’t. Keep red as + on all cameras, and black as – .   Consistency is the key especially if you didn’t follow hint #4. (12V DC IS polarity sensitive – it is our #1 cause of camera damage during installation.)

So the moral of this story is – the right cable can make or break a great system. Talk to the manufacturers of your equipment and tell them your situation.  There is no such thing as a “one size fits all” surveillance package.  All of
the equipment from the DVR, to your cameras, to your cables, to your power supply and monitor should match your needs specifically.  A company that takes a few extra minutes to make sure you get the correct cable, and lengths of cable can save you hours / days of hassle in the field.

This article was written by Jennifer Spears – Business Solutions Manager at Rugged CCTV.  For more than 11 years, Jennifer has guided thousands of businesses through equipment selection, system design and initial setup.

Contact email:  jennifer@rugged-cctv.com – Phone:   1-866-301-CCTV.

© Copyright 2011

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