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#160237 - 08/02/05 05:09 AM CCTV  
poorboy  Offline
Joined: Jun 2005
Posts: 124
Central Maine
Planning a job for a local high school installing security TV. According to the salesman the very expensive cameras can do their job from the 50 ft high roof, aimed down at entrances. This is going to make the coax runs quite long. One may be 500 or 600 feet from the monitor...the others prob about 300. We are using the copper braided coax as we were told that CCTV unlike CATV uses the shield as a conductor.

What length restrictions apply and if a more direct route is impossible what kind of amplifier could be used to make this possible?

The 24 volts for each camera or group of cameras will be picked up near each camera location, as panels are nearby. Camera boxes will have heaters, and I will have to look at them to see what they draw at 24 volts...any input on how near to a group of 3 cameras my power supply would have to be to be OK? Could I go 100 feet to a couple of cameras with 24 volts for camera power and heater power?

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#160238 - 08/02/05 07:12 AM Re: CCTV  
hbiss  Offline
Joined: Dec 2003
Posts: 886
Hawthorne, NY USA
These are all design issues that are best answered either from experience or by the manufacturer. I doubt that you will have any problem signal wise with the lengths you have, however power may or may not be an issue. Do you have the tools and know how to terminate the cables properly with BNC connectors?


#160239 - 08/02/05 07:19 PM Re: CCTV  
poorboy  Offline
Joined: Jun 2005
Posts: 124
Central Maine
Yes. Did a small 5 camera system last year in which cameras were all within 100 ft of the nurses station on a memory loss ward of a nursing home.

The salesman who sold the system to the school is our contact person on this job, whereas the fire alarm techs (whose company provided the system on the memory loss job) gave us the help we needed on the nursing home.

The salesman is no technician and while I am sure he can steer us onto the right people, and we will be including him in our planning of the job, I wanted to get a few facts straight on my own first.

#160240 - 08/03/05 03:41 AM Re: CCTV  
techie  Offline
Joined: May 2005
Posts: 246
palo alto, ca usa
If you are running 24 volts directly to the camera, then you're probably not going to be using the coax to supply power. (there are cameras where the power is provided over the coax, some Sony cameras come to mind.)

You might also look at using baluns and cat5 for the video runs, they may perform better than coax over a long distance.

The catalog that I'm looking at advertises some of the active baluns as being good for 7800'+,
and the passive baluns at 1000', and 1968' with camera power on the same cable.

#160241 - 09/02/05 12:59 PM Re: CCTV  
macmikeman  Offline
Joined: Jul 2002
Posts: 717
Honolulu, Hawaii
Poorboy, I do not wan't this to seem like I am in the business of promoting vendors or manufacturers, but in this one case I will. In my own experience having done over 500 cctv camera's on one job, I found the people at ADI to be extremly helpful on design issues when asked.

#160242 - 09/05/05 09:15 PM Re: CCTV  
JCooper  Offline
Joined: Dec 2002
Posts: 228
Kendall Park, NJ USA
Are you sure the cameras are going directly to the monitor and not to a quad/mux/dvr before they hit the monitor? 500-600' should not be a problem, I assume you are pulling RG-59 to all the cameras. Worst case you can put an amp at the head end equipment if you see some signal degradation. If you wanted to be proactive you could pull RG-11 to the further cameras, RG-59 has a 20awg center core whereas RG-11 has a 12awg if I recall correctly, all you are dealing with is voltage drop in the signal. If the cable is unterminated at this point you should try to install two or three piece BNC connectors, not the twist on types, I have cut off hundreds of the twist ons. You do need a crimp tool for the multi piece connectors, but they are not all that expensive and are can be picked up at almost any supply house or even HD or Lowes. Another option which was suggested was using baluns on some sort of twisted pair, normally CAT3 or better. This can help cut down on the length of your cable runs if they have some house pairs you could cross connect on to. Running a CAT5 to each camera also gives you three extra pairs which could be used if something happend during the pull and you have a bad pair or if they decide to add cameras later on the cable is already in place. I just finished a job at a convention center with 64 cameras on active baluns and there were runs over 2500' with no prolems.

As for the power, if these are fixed cameras with heaters in them and the run is around 100' you should have no problems with 16awg power cable, you should even be ok up to about 250'.

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