PaulsonLaw 0 Posted May 22, 2012 (edited) (UPDATE) Got another unit in for another gig, swapped DVR's, same nighttime fabric interference. Play around with power packs, nothing, put on one of the new cams for the other unit, perfect.... SO, watch out on energized metal siding/soffit buildings! ............................. So this last job I had posted about a few times... Turns out... The steel siding/roofed 1500sqft pole building that 4 cams were ran out to did not have a bonding ground to the shell... Ran cat5 from house for 4 cams and a panel bonded ground as for 2 different meters.... Problem is, directly behind the garage are some low transmission 69,000v power lines, about 15' away maybe, along with regular lines for pole drops.... Problem was, only after metering metal shell to ground, was that the leakage from these lines was absorbed in the shell & when checked to ground, 750mvAC. This power was sent through the camera mount, down the coax ground shielding, down the cat5, right into the DVR.... This damaged whatever part of the DVR reads the IR Frequency so at night when the IR's came on, the screen was layered with fabric like interference.... So, before ever installing on a large metal building, always check the shell to ground to make sure it's not energized. Edited May 27, 2012 by Guest Share this post Link to post Share on other sites
nDAlk90 0 Posted May 22, 2012 Good idea. So you mean to say the exterior metal siding of the building had some power? Wow... So, before ever installing on a large metal building, always check the shell to ground to make sure it's not energized. Share this post Link to post Share on other sites
Soundy 1 Posted May 22, 2012 Ran into something similar recently... IQA11 dome on the outside of a building would go down... came back after a power cycle... go down again a day or so later. Camera was in the sun and had obviously been running very hot (part of the plastic inside was deformed) so we figured it was hooped and replaced it with a HIK dome. That went down about two hours after I left the site... Came back to site, pulled the camera off... and it came back to life. After much fiddling, it really appeared to be a loose connection, as it would drop off as soon as I twisted the dome into its wall bracket. Then I discovered that it would drop within seconds of even TOUCHING its bracket... which was attached with 3" deck screws through the Alucobond shell, through an air gap, and into the plywood behind (Alucobond is "a light composite material consisting of two aluminium cover sheets and a plastic core"). So I pulled out the multimeter... and found a reading of 8VDC, and 4.5VAC, between the bracket and Alucobond, and the ground on my power connector. Whoa... 12VDC power to the camera is through a 1A regulator board, fed from one channel of the 24VAC power can. Tried removing the ground lug on the power supply's cord, to no avail. No idea where this potential was coming from, but it sure ain't normal. No HV power lines around like in OP's case though. Ultimately, I drilled out larger screw holes through the Alucobond (so the screws wouldn't contact it), put heat-shrink tubing over the upper shaft of the deck screws (to insulate them from the Alucobond and bracket), slipped a rubber O-ring over the screw as well (to isolate the screw head from the bracket), and cut out a cardboard gasket to go between the bracket and the Alucobond. I still had a very small (0.8VDC) potential between the bracket and power ground, but it was sufficiently isolated so the camera worked again... Share this post Link to post Share on other sites
nDAlk90 0 Posted May 22, 2012 So basically to disable an IP camera you just have to apply voltage to its housing... Thats seems like a design flaw... Anyone with a battery can disable the camera when they need. Ran into something similar recently... IQA11 dome on the outside of a building would go down... came back after a power cycle... go down again a day or so later. Camera was in the sun and had obviously been running very hot (part of the plastic inside was deformed) so we figured it was hooped and replaced it with a HIK dome. That went down about two hours after I left the site... Came back to site, pulled the camera off... and it came back to life. After much fiddling, it really appeared to be a loose connection, as it would drop off as soon as I twisted the dome into its wall bracket. Then I discovered that it would drop within seconds of even TOUCHING its bracket... which was attached with 3" deck screws through the Alucobond shell, through an air gap, and into the plywood behind (Alucobond is "a light composite material consisting of two aluminium cover sheets and a plastic core"). So I pulled out the multimeter... and found a reading of 8VDC, and 4.5VAC, between the bracket and Alucobond, and the ground on my power connector. Whoa... 12VDC power to the camera is through a 1A regulator board, fed from one channel of the 24VAC power can. Tried removing the ground lug on the power supply's cord, to no avail. No idea where this potential was coming from, but it sure ain't normal. No HV power lines around like in OP's case though. Ultimately, I drilled out larger screw holes through the Alucobond (so the screws wouldn't contact it), put heat-shrink tubing over the upper shaft of the deck screws (to insulate them from the Alucobond and bracket), slipped a rubber O-ring over the screw as well (to isolate the screw head from the bracket), and cut out a cardboard gasket to go between the bracket and the Alucobond. I still had a very small (0.8VDC) potential between the bracket and power ground, but it was sufficiently isolated so the camera worked again... Share this post Link to post Share on other sites
Soundy 1 Posted May 22, 2012 I suspect the potential in the building was working against that from the power supply - ie. power supply was at 12VDC, but lifting the relative earth ground to 8V meant the camera was only seeing 4V when grounded. Simply applying a battery wouldn't do anything because one terminal of the battery would have to connect somehow to the camera's own power ground... doing that would require access to either the inside of the camera, or the camera's power supply... either of which makes it easy enough to disable the camera without using a battery. Share this post Link to post Share on other sites
dustmop 0 Posted May 22, 2012 I'm filing all this information away for when I have to do work over in the giant metal barns. We have some 69kv lines running right through the property. Thanks for a follow up post! Share this post Link to post Share on other sites
PaulsonLaw 0 Posted May 22, 2012 Good idea. So you mean to say the exterior metal siding of the building had some power? Wow... So, before ever installing on a large metal building, always check the shell to ground to make sure it's not energized. That's correct! The metal siding & and roof! The only thing we can think is leakage off the very nearby 69,000 power lines. 750mv when putting a good meter from the siding hex screw to a copper wire stuck in the ground, opposite side meter/breaker box. Forgot to list how we resolved this... So starters we bonded the roof to siding w/ small tucked away ground wire. The bonded siding near ground to 3' ground rod. The dismounted the cameras & used a piece of composite decking cut down to mount cams to, then mount small composite to soffit. Just to be safe, I'm going to pull the cams back down & shrink tape the BNC connecters so they don't touch the shell while laying up in the soffit.... Glad to see we were not the only ones Sadly, even after that, the DVR got a little jacked, HD is recording real bad & bad "fabric" like interference when the IR's kick in on all channels, not just the 4 on the metal garage.... Share this post Link to post Share on other sites
