BNC Connector Styles for Coax Cabling
By Jennifer Spears
So you are going to hang security cameras and you’ve decided to pull your own cabling from a spool of cabling instead of going with pre-made cables. Good for you! Promise you won’t regret it. You’ll have a cleaner installation, plus much cleaner video since you won’t have a huge mass of coiled up coax sitting there pulling interference directly into your cable.
The power side of your cabling is normally real easy. All you have to do is strip off the vinyl layer protecting your 2 conductors and then strip off around ½” from the black and red wires. Then connect it to your cameras terminal block or power leads that should have been provided with your system. Make sure and remember most cameras are polarity sensitive for 12V DC voltage. You reverse the polarity and you’ll get to fork over money for replacement cameras.
Now that the power connection is done you are ready for the coax or video side of your cabling. You may have RG59u or RG6u coax cabling. Before you buy connectors make sure and determine which kind of cabling you have because if you buy the wrong kind they either won’t work at all, or will be so poorly finished you’ll have to redo them.
The options you have on standard types of video termination connectors for coax cabling, specifically for surveillance equipment, are two piece connectors, compression fittings, and the dreaded twist on connectors. These are all BNC connectors. Mostly what people terminating cables need; are the male end since your cameras and DVR are already going to be terminated with female ends. The female ends are static and do not move at all or rotate. The male ends should be free spinning after terminated and this is a good test to perform after you terminate a cable to make sure it was terminated properly.
OK so I’m going to talk about the connectors in order of easiest to hardest. None of them are particularly difficult but some do have a bit of a learning curve to get perfect. I’ve made YouTube videos for you to make it much easier to see what you are going to be doing. Plus you can see the kinds of tools necessary as well.
Twist on Connectors – Let me make it easy on how I feel about these…YUCK!!! Simply they are called twist on connectors, because they can twist off just as easily. They WILL NOT last outside, not in wet environments, and the slightest tug on the cable will have them pulling interference in or losing signal all together. These are way outdated, so don’t use them.
Two piece Crimp Connectors – this is my personal choice. Yeah, yeah this is just supposed to be informative and I’m supposed to keep my opinion to myself – NOT! These are fairly easy to terminate, they last a very long time (I’ve got some that are going strong after 11 years after being crimped), and the tools and connectors for that matter aren’t as expensive as the compression fittings.
The connectors have two pieces that when terminated correctly will look like one at the end. Along with the actual connector there is a ferrule or sleeve that slides over the coax, and once the cabling is stripped down properly, the copper braid will be sandwiched between the connector and the ferrule. This is what holds the connector securely in place.
These connectors are much more forgiving on length of center conductor, insulation and copper braid. The margin for error is much lower and people can get the hang of these much faster. Knowledge = money so you don’t go through a bag and half of connectors just trying to learn how to work them.
Here is the YouTube link for Two Piece Connectors – http://www.youtube.com/watch?v=Qzk70QX9Aac&feature=player_embedded
Compression Fittings – these are the style that most professional installers use. They have the longest learning curve, tools and connectors themselves are more expensive, but they are also the longest lasting and the most moisture resistant. You can even get the gel filled variety and then the cables are effectively submersible in water.
The connectors are only one piece normally, as long as you get the kind with the stinger pre-inserted. These are very easy to identify since they will have a color, or more often than not, two color bands around the barrel of the connector closest to the cable insertion end. When the connector is compressed the colored band expands towards the cable and locks it into place. The large colored band disappears when the connector is compressed leaving only the secondary smaller colored band. This is to let you know the compression has been successful.
You have to be almost exact with measurements on the stripped down cable with these connectors. If the center conductor or insulation is two long when you compress the connector it falls off immediately or with a gentle tug. If either is too short you won’t get good connection for your video and you’ll have to cut the end off and try again. Both of these add up quickly, and can suck money out of your wallet when each connector is a few bucks a pop.
Here is the YouTube link for Compression Fittings – http://www.youtube.com/watch?v=PAR87h0irrY&feature=player_embedded
To terminate your coax you will need your cabling, coax stripper, crimp or compression connectors, power wire strippers (you will use these for both your power wire and the coax), crimp or compression tool, and electrical tape. I recommend taping all connections once they have been made and connected into your camera pigtail. It makes for a more secure and cleaner install.
Here are a few things to watch out for no matter which type of connector you use.
Make sure and follow your termination instructions very carefully. Length of your center conductor, insulation, copper braid and outer vinyl are vital to good video signal.
Don’t tug on the cables. Yanking on them will stress the cabling all the way down to the center conductor and can weaken or even break your connection. You can also pull so hard you pull the pigtails out of the camera itself and that is most definitely not covered under warranty.
Wrap it with electrical tape or shrink wrap of some kind. It helps protect the cabling from moisture as well as metal to metal grounding which nasties up your picture.
Make sure before you slide your connector onto your center conductor that NONE of the copper braid touches the center conductor. This creates a phenomenon called ground looping. Ground Looping = Bad Picture and it is incredibly hard to trace.
Don’t make sharp angles with the cable. It will weaken or break the center conductor and then you will have to run a new cable.
If you are running a lot of cable, invest in a coax tester. They are not very expensive and well worth it when you can’t get a video signal. You’ll know in about two seconds if there is a problem with the cable or the camera itself.
As an aside, coax cables can also be terminated with lots of other types of connector styles. Mainly they would be RCA and F connectors. RCA terminations are mostly used in residential grade systems and the equipment in general won’t last as long as commercial grade. F connectors are what you are used to seeing on coax for your cable or DIRECTV connection. They are a threaded connector with a stinger in the middle. It has nothing to do with surveillance equipment and will not be used for your cameras.
Hope this helps!