Power Over Coax (PoC) CCTV Explained - What It Is & How It Works
If you’re about to have a new CCTV system installed or are in the market for a new one. You may come across the term PoC camera or something similar and wonder, what is PoC? In this article we discuss what it is, the advantages and disadvantages or Power Over Coax and compare it to other systems like Power Over Ethernet (POE). Without any further ado, let’s begin.
What Are POC Cameras?
A POC camera is one that doesn’t require a separate DC power connection as the DC power for the camera is provided via the same coax cable that provides the video images. This is a similar concept to systems like line powered TV amplifiers and Power Over Ethernet. The advantage of this type of system is that the only connection that is required at the camera is the RG59 BNC connection, which can make for an easier and tidier installation with less material costs.
DVR Must Also Be POC Compatible
To use a POC camera, the DVR must also be POC compatible. If it isn’t and with no separate DC power supply to the CCTV camera, the camera will not be powered and will not work. You must also ensure within the settings of the DVR that the POC function is switched to on to ensure that the DC voltage is provided to the camera.
POC Camera Power Supply Unit
At the time of writing this, I have yet to discover a manufacturer or supplier that provides a separate PSU for the powering of PoC cameras like you would do with a PoE injector or a PSU for powering TV masthead amplifiers. I’m sure that they do exist somewhere or will be brought to market soon. An advantage of this type of system is that if you only have a coax cable at the camera position but do not have a PoC compatible DVR, a separate PoC injector/ PSU could be installed to make this set up work.
What Voltage is Power Over Coax CCTV?
Hikvision CCTV systems that we work with work over 48V DC for distances up to 200 metres, which is switchable from within the settings of the DVR. Other manufacturers such as Dahua use a 12-36V DC. Non PoC cameras (with a separate power supply) are suitable for use with PoC DVR’s but you should make sure that you switch the Power Over Coax function to off to prevent any stray voltages at the camera.
Power Over Coax (POC) vs Power Over Ethernet (POE)
Both of these protocols are similar in what the achieve but Power Over Coax is a 48V DC power connection (other manufacturers other than Hikvision may use different voltages) provided down the same cable coax cable that carries CCTV images. Although the technology has been about for several years now it has only recently started to be rolled out on CCTV installations.
Power over Ethernet is much more established and used across a wide range of sectors including, CCTV, data/ networking, WIFI, access control, and many more. For CCTV PoE primarily used for IP CCTV installations where the power is either provided directly from the NVR or via a PoE injector or PoE network switch. This means that only a single data cable, like a Cat5e or Cat6 cable is required at the camera position. Power over Ethernet works by providing a DC power connection down an data/ network cable, there are many standards now but usually this is either 24V DC, 48 DC, or 54V DC. It’s important that when using PoE products that you ensure you are providing the device with the correct supply or it will not work and you could cause damage to the equipment.
What Cable Is Required For POC CCTV?
The cable used for Power Over Coax is RG59 like other analogue CCTV systems with the cable terminated in a BNC plug at both the DVR and camera positions. You could also use a larger cable like RG6 for the installation which would also be suitable for carrying the DC over the coax, but this type of cable doesn’t fit the crimp on plugs BNC plugs that are used for CCTV so you will most likely need some adapter plugs to make it fit, like an F to BNC or coax IEC to BNC for example.
Advantages of Power Over Coax CCTV
The obvious main advantage is that only a single coax cable is required between your DVR and camera, no extra DC power cabling or “shotgun” cable is required. This makes for an easier installation, with less cabling costs (probably offset by the additional cost of the DVR/ Camera) and a tidier installation. I would suggest that the latter is perhaps the main attraction to PoC systems as it can get a bit messy behind some DVR’s with all the cable connections, DC plugs, excess cabling, etc and just having the coax can really tidy things up. It also means that one less mains electrical socket is required for the system which could be used for something else.
Disadvantages of Power Over Over Coax CCTV
I have to say, the biggest disadvantage I have found with POC CCTV systems and the reason I mostly stopped using them, is the loud noise of the DVR. I have found that with the extra power being supplied to the cameras comes with additional fans to reduce the temperature of the CCTV DVR. Although not the best idea with domestic CCTV systems, it is common practice to site the DVR near a TV so it be used as a monitor. A noisy POC DVR within a lounge is completely unsuitable I would suggest. This is not as much of a problem however with commercial CCTV installations for business, where often the DVR will be sited within a lockable cabinet, Comms room, or similar. If you have the skillset you could always swap out the fan inside the DVR for a quieter one, but be mindful that doing this will likely invalidate any warranties that you may have.
CCTV Power Questions
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Until next time,
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