tesc_cctvpro 0 Posted January 15, 2008 I am looking for tips on securing a CCTV system against lightning. embedded DVR, central Power Supply Unit and cameras installed outdoors atop galvanized steel poles. There are many half solutions with no guarantees, is their a definitive , 100% solution? Share this post Link to post Share on other sites
survtech 0 Posted January 15, 2008 No, there are no guarantees. The best you can do is follow good cabling practice and install surge protectors. Unfortunately, lightning can always find ways into a system. Share this post Link to post Share on other sites
tesc_cctvpro 0 Posted January 15, 2008 Ok, So, following good cabling practice will reduce the risk of damge by X%, is their any definitive measure for this. My point is. The risk factor for lightning damage to a cctv system is X%, if I tell my customer to invest a few more hundred dollars on Lightning rods, earth bars, surge protectors, and they ask "so this will protect my system against damage?" --- I have to answer , "no - it may reduce the risk, but there are no guranatee's" , next question is "what are the chances of my system being damaged by lightning?" So. Everything connected to the mains, comes through a surge protector. All video lines are fitted with an inline surge protector, earthed to a earth bar in the control room. each individual camera is fitted with an inline surge protector, eartherd to ground at the camera location. The power supply is fitted with fuse protection for each individual channel, and each cameras power feed is fitted with an individual surge protector, again connected to earth. My understanding is that the power differential tries to balance first within the camera - despite this, and then tries to feed back down the cable to earth. So in addition to the above, all outdoor cameras should be below a lightning rod which is earthed to ground. To be frank -- If I included this in my estimates , and a lot of the work may only be performed by a qualified electrician, I would not win a single bid. Most of my competitors merely exclude this and put a disclaimer about lightning damage in the estimate. While my contracts also stipulate this disclaimer, I don't enjoy the idea of washing my hands when the system , I have installed is damaged. Share this post Link to post Share on other sites
Rooney 0 Posted January 15, 2008 Unfortunately there is no "100%" gaurantee. The method you stated should be an effective measure. I am in a lightning rich environment. When we do installations we do the following: 1. If camera is on a pole install lightning rod above camera and tie to ground rod. 2. Install surge protector on camera power and video feed at camera end and ground to rod. 3. Install surge on video feed at control end and ground sufficiently. 4. If cameras are PTZ also install surge on all control wires at both ends. 5. If camera feeds are underground they should be installed in IMT conduit or better. Conduit should also be grounded to rod at each end. The main thing with lightning protection is BONDING. Anything and everything that has a potential to "indifference to ground" must be bonded and grounded. If you do the above you will help the system through "most" events. Lightning is very unpredictable. You may have a strike that has 1 million volts with low amps one minute and one with 1 million amps with low voltage the next. Share this post Link to post Share on other sites
tesc_cctvpro 0 Posted January 15, 2008 Thanks Rooney, Exactly what I was hoping for -- examples of what others are doing. Just had another major thunder storm as i am typing here Perhaps third one this week Share this post Link to post Share on other sites
Rooney 0 Posted January 15, 2008 No, there are no guarantees. The best you can do is follow good cabling practice and install surge protectors. Unfortunately, lightning can always find ways into a system. I installed a system at an actual lightning testing site a couple years ago. It is still working today with only routine maintenance (i.e. cleaning and occasional power supply or camera problem). A system CAN be made to withstand lightning. The major thing is most installation companies do not understand the science behind lightning protection. They just put a disclaimer or sell the customer high dollar protection and not install it correctly. The main thing with lightning is bonding everything together so there is no potential difference to ground. As the electrons will take the path of least resistance. I have had a camera get struck directly and survive with no problems except the housing had a small hole melted in it. When you opened the housing you could see the line it took to the grounding system. Share this post Link to post Share on other sites
tesc_cctvpro 0 Posted January 16, 2008 With regards to bonding....... What in addition to those steps already mentioned is required to be bonded? Also what would you use for earthing equipment, wire or metal straps? Brandon Share this post Link to post Share on other sites
zmxtech 0 Posted January 16, 2008 fiber optic`s converters will protect the video from the poles to the DVRs using UPS`s and separate supplies etc.. z Share this post Link to post Share on other sites
Rooney 0 Posted January 16, 2008 With regards to bonding....... What in addition to those steps already mentioned is required to be bonded? Also what would you use for earthing equipment, wire or metal straps? Brandon For bonding I use wire (solid 12-10 awg) from the surge devices, and copper braid down the poles from the lightning rod to the ground rod. I then use a copper ground connecter to connect the surge wires from the camera to the braid going to the ground rod. Also bond the camera housing to the ground system. The main thing is you want the resistance to be as low as possible. I ussualy use an ohmeter to test the resistance from the camera to the ground rod. The lower the number the better (less than 1-2 ohms). Share this post Link to post Share on other sites
chanyickwai 0 Posted February 20, 2008 I found another stream of same discussion. viewtopic.php?t=11560 Regards, Dove Share this post Link to post Share on other sites
Joseph 0 Posted February 27, 2008 fiber optic`s converters will protect the video from the poles to the DVRs using UPS`s and separate supplies etc.. z Lightning damage could only be reduced, but can not be guaranteed like "keep away from my device". To fiber optic transmission systems, they usually add independent anti-lightning chips on PCB port, and make sure grounding, so that can reduce the rate of damaging by lightning. BTW, F.O. products designed with surge protection, to provide device working safely in any different current level. So far as i knw, there are only a few Chinese company's F.O. products designed like that, and indeed, their products do good performance in outdoor. Share this post Link to post Share on other sites
crirvine 0 Posted February 27, 2008 We are using GE fiber to copper units 3 ptz's and 1 4 chamera to 1 fiber unit all ptz's are outside on 60 foot rohn 25G towers. The only thing we have to do is reset the power on the fiber units not very often at that. Share this post Link to post Share on other sites
