CCTV Systems
By John W. Colley

Grill The CCTV Expert
December, 2003 Issue

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John W. Colley

What should our sales engineers look for when the customer asks for alarm call up of preset positioning of the video system?

Each manufacture may address the application differently the one I am familiar with approaches the presets with local call up of up to 16 presets for the pant, tilt, zoom and focus functions. The optional unit should have sixteen dry contacts are available to make connections to a corresponding preset position. It is important to research the pan, tilt receiver has preset positioning capability.


When our company is specifying and an exterior power supply for video or card access applications what should we consider a sufficient product.

Our first consideration is the manufacture and what has been the record of accomplishment of this company in supporting the products they offer. Once a business decision has been made we proceed in the specific product selection.

An exterior power supply should offer a weatherproof linear supply and charger. Why a charger and not just a power supply? Many customers want their CCTV System to operate even if the power goes off. The charger and battery option is a low cost alternative to running emergency power to all camera locations. The customer will need to decide the amount of power back up time is required versus the expense.

The power supply would include an 115VAC power source, 60 Hz at 9.5 amps. Output options should include 24 VDC and in some cases is 12VDC or both. The continuous supply current will be in the .5 amps area. We have found filtered and electronically regulated outputs provide better performance.

Built in-charger would be able to charge sealed acid stand-by battery. All inputs should be fused to protect the battery. The manufacture offering must include and electronic switch over to battery stand-by In addition, the power supply should a field LED indicators whether the power supply is working to assist your field technicians.

Our technicians are always running into field issues with 12VDC or 24VDC power. The sales team always mixes product either in the choice of cameras or the power supply. Is their field device we can purchase off the shelf that gives us more flexibility between 12VDC and 24VDC applications?

Yes product is available to answer a common dilemma we all seem to get ourselves on projects. We the engineering team recommend a power conversion module. The module converts 24VDC to 12VDC or vice versus to switch VDC. Our choice includes a 1-amp output, built-in overload protection, which is electronically filtered and regulated. The size of the unit allows us to mount in convenient locations and offers modular connections for ease of installation.

Our technicians were discussing the quality of recent video installation and were confused why they had two cameras the same quality in the same lighting but different distances and one camera looked different. The customer has come back to the salesman and asked him to either fix the problem or take the CCTV out. Why do we have this issue?

First area to look at is the cable installation. Make sure that a quality choice of coaxial cable was used. You should use a minimum of RG 59U with copper braid. Next, look at the connectors to make sure the connections are made properly. If these are correct, check the power cable. You will need to make a judgment of the power requirements usually before the installation but in this case, I will give a typical calculation that may be causing the issues.

An example of using 16 AWG versus 22 AVG:

16 AWG Example: Power Source (120 AMPS), Wire gauge (16 AWG) length of cable (500 feet) voltage drop (480.18 V)

22 AWG Example: Power Source (120 AMPS), Wire gauge (22 AWG) length of cable (500 feet) voltage drop (1921.4 V)

As you can see, selecting the right gauge wire for the power cable distance is important. Please check you installation and see if this is your CCTV issue.

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John W. Colley is president of Integrated Security Systems, Ltd. and has been in the security industry for over 25 years, beginning his experience in the CCTV segment of security and gaining knowledge through field experience, manufacturer training and designing systems to meet customer needs. Colley started his security integration firm 18 years ago, providing design, engineering, installation and service to commercial accounts using integrated systems. Send your CCTV/Surveillance questions to jwc@securityiss.com.