Subscriber Discussion

Strange Issue Keeps Damaging Cameras: Help Needed

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Alan Dodds
Jan 24, 2015

Hi everyone.

I was wondering if I could get some suggestions or ideas on how to fix an ongoing issue we are having with a CCTV system in a horse ranch in Scottsdale AZ.

I'm a low voltage systems/AV integrator in the Phoenix/Scottsdale area and have "inherited" a client's existing CCTV system. It's been up for over 5 years but the issue is relatively new (at least to the extent that it is now). The system includes 2 IC Realtime DVR's (16CH/8CH) and 24 analog cameras (12V & 24V). It's a fairly large horse ranch in our local desert with cameras spread out throughout the ranch. Wiring is originally CAT5 & 18/2, though the main building uses RG59 as well. Some of the CAT5 outdoor is buried and some is running inside metal fence tubing before running up metal conduit and/or posts.

Back in September, during a rain storm with lightning, 8 cameras went down (a mix of brands and locations). No surge protector was tripped, DVR's kept working, no sign of damage anywhere except 8 cameras were for all intents and purposes "broken". All the cameras were outdoor cameras mounted on poles or metal frames for pens, arenas, fences... After testing all video lines and power supplies, I replaced all the cameras with quality analog equivalents (self-branded by a lesser known reseller in Las Vegas with whom I have done business for a while). Checking the DVR feeds, it was clear that all cameras went down at exactly the same time (during the rain, middle of the night). The picture seemed to flash bright and then went black).

I just got a call from my client a couple of days ago that 6 cameras were out. it turns out all 6 were part of the group I replaced recently. So I went straight to the recordings and again found that all cameras that were recording at the time went out at the same time on the same day. Except this time, no rain, no lightning, and it was during the day at around 4 PM.

Needless to say, after replacing the first batch of 8 cameras at cost or at a loss to maintain a good relationship with our client, I am now very reluctant to proceed with a replacement without figuring out exactly what happened. Again, no surge protection event, no damaged power supply (except for one 24VAC to 12VDC converter).

All cameras are mounted on metal structures with connection to ground. I'm guessing the issue is some sort of strange electrical phenomenon which bypasses the surge protection in place. Perhaps it's from the ground, but note that the cameras are in 3 general locations sometimes more than 100 yards apart.

I hope that's enough background information. Video surveillance systems are a common installation request but are not necessarily our specialty. I'm hoping the wealth of experience here at IPVM can combine to help us resolve this issue once and for all.

Thank you all in advance.

Alan

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Trisha (Chris' wife) Dearing
Jan 24, 2015
IPVMU Certified

Hi Alan, a couple questions that might help:

  1. Does the conduit and/or metal frame connect to the camera ground or camera case/enclosure (if it's metal)?
  2. Is there surge suppression on the AC, the coax, and the category cable?
  3. Is the surge suppression right at the camera or centralized?
  4. What do the the eight/six camera locations share? (Meaning how might they be electrically connected: conduit, power supply, switch, encoders, surge, extenders)
  5. Was a post mortem done on the cameras to determine whether the surge came through the power or the video?

Thanks

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Alan Dodds
Jan 24, 2015

Hi Chris.

1/ Yes. It's been the case from the original installation.

2/ AC only. I'm not sure how I would add it to 24 cameras (CAT5 w/baluns or RG59)

3/ Centralized. Nothing high $, pre-existing my involvement.

4/ Cameras 1&2 share the same 24VAC power supply and are near each other but on different structures; cameras 3&4 have different power supplies but I believe share the same CAT5 for video and are on the same metal post; cameras 5&6 share the same 12VDC power supply and are relatively close but on different posts separated by a gate and some fencing. All power supplies are still OK. There might be some additional shared "wiring" but I can't confirm from memory.

5/ No. I don't believe the supplier has the means or expertise nor do we.

I also know there are some significant voltage fluctuations at the ranch as guests staying at the ranch in an RV (very close to 1&2, not far from 3&4) have reported alerts from their computers' UPS. At this point I have asked the client to hire a licensed electrician to test power in various locations associated with the cameras (from the DVR room to the RV area and the gate/fence area. I'm also inclined to add UPS with Automatic Voltage Regulators on all the camera power supplies. Finally, though I am no expert, there might be "stray" voltage in the ground and I was thinking of totally isolating each camera by mounting them on PVC junction boxes.

I'm willing to take my share of responsibility for the issue here as perhaps best practice would have had me recommend some changes in the original set up and installation, but I'm not sure I should be shouldering the whole cost of this "repair" either. Feedback on this would be appreciated as well.

Thanks again for your help.

Alan

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Brian Rhodes
Jan 24, 2015
IPVMU Certified

Are all the cameras outdoors, or are some indoors as well?

EMI from cloud to cloud lightning or even static from blowing dust could contribute to failures like this, but I've never heard of so many units failing at once. Usually it is one or two, not 6 - 8.

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Alan Dodds
Jan 24, 2015

Yes, Brian.

All the failed cameras are outdoors.

I've never encountered the issue before. With lightning and a rain storm, I could stretch into act of God type of explanation with no expectation of it repeating (since as I said this system is about 5 years old and it had never happened before from what I've been told). But now, though the circumstances are a bit different and the number of cameras somewhat less, it's twice in a few months.

Alan

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Trisha (Chris' wife) Dearing
Jan 25, 2015
IPVMU Certified

Alan, thanks.

Although I am not an electrician, I feel comfortable saying that in order to prevent lightning surges from taking out your cameras you will need at a minimum a coax surge suppressor and a power surge suppressor 12VDC or 24VAC at each camera, each with a good ground connection. Personally I have only used relatively cheap ones, to no ill effects yet, but others cost 2x to 5x more. And they may be worth it. I don't know. I'm sure plenty of members have advice on whether they are and no doubt have war stories to share. But even for the cheaper ones you are looking at $25-50 per camera.

Also you will want coax surge protection for the head-end, though here you can buy a multi-channel one, like your 24VAC power one. As for the conduit, if it itself makes an electrical connection between cameras or other equipment, that path should be eliminated at some point after the conduit is in the ground.

I don't claim this is all you need, but I don't think there is any way to ensure it won't happen again without it. Your client's on-site electrician of course should be the final word...

Also, is there a reason, like distance, that you didn't go POE on the replacements?

As for the money, If your client has seen you replace 8 cameras at your own cost, due to an apparent act of God, he should not doubt your integrity in the least. And since you didn't spec the original system, I don't see why you would be on the hook at this point for the new cameras and added cost of protection.

But in the case of the first failure, where it was clearly a lightning strike, his homeowner's or business insurance would normally cover at least some of the damage, did he not make one or was his claim denied?

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Carl Lindgren
Jan 25, 2015

Alan,

You say this is on a ranch and that the cameras that blew out the second time were all powered by 24VAC? My thoughts on this are that for the two separate instances of multiple camera failures, we are looking at two separate causes:

The first instance is almost certainly lightning. Lightning's effect is completely unpredictable - the only predictable thing is its unpredictability. Since both 24VAC and 12VDC cameras failed, likely a surge was induced directly into the video wiring since the voltage regulation in DC power supplies would typically prevent the voltage from exceeding its setting. Many DC power supplies can accommodate a wide range of input voltages and still deliver the correct output voltage, at least for relatively brief periods (for longer periods they could overheat).

AC supplies have no regulation - they are simple transformers. In an AC camera power supply, the transformer converts voltage on an approximately 5:1 ratio.

Let's say the line voltage spiked. This can happen for a number of reasons, from high power equipment somewhere on the local grid turning on/off to a lineman hooking up something wrong to wind blowing a high voltage wire against a lower voltage wire, etc. If the cameras are powered by a DC power supply, depending on its design and how long the spike lasted, it is very possible their voltage would remain relatively constant. Not so with the AC-powered cameras. If line voltage spiked to 240VAC, camera power would also spike - in theory to 48VAC. Actually, most 24VAC supplies actually provide 28-29V under low-to-moderate loads. Since they are unregulated, the higher the current draw, the lower the voltage so they are typically designed to run on the high side of rated voltage.

Power stability is often poor in rural areas due to the long distances from substations, aging equipment (rural areas are not high up on utility priority lists) and the vagaries of weather.

The only way to tell with relative certainty would be to perform a post mortem exam of the failed cameras to determine what circuit(s) failed.

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Carl Lindgren
Jan 25, 2015

One final point: since you didn't install exactly the same cameras as the original ones, it is very possible the newer ones were more sensitive to voltage spikes. That could be why the first cameras lasted until the system was hit by lightning whereas the newer cameras failed more quickly.

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Undisclosed #1
Jan 25, 2015
IPVMU Certified

The first instance is almost certainly lightning... ...the voltage regulation in DC power supplies would typically prevent the voltage from exceeding its setting.

To be clear, are you saying that devices that use DC regulated power supplies are 'typically' protected from surges generated by lightning?

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Carl Lindgren
Jan 25, 2015

Undisclosed,

Two different things. Since it is almost impossible to predict the path of lightning or its effects, it is also impossible to predict whether DC power supplies would prevent problems caused by lightning. In the case of line power surges, regulated DC power supplies would likely be less prone to "frying" the cameras than AC power supplies.

So in the case of lightning striking the power grid, it would depend on too many variables to predict with any degree of confidence, other than to say that regulated supplies are less likely to spike their output voltage if their input voltage spikes.

U
Undisclosed #1
Jan 25, 2015
IPVMU Certified

Therefore your conclusion that

...likely a surge was induced directly into the video wiring...

does not hold, since it was clearly in reference to the first incident, which you characterize as "almost certainly lightning", yes/no?

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Carl Lindgren
Jan 25, 2015
Whatever.
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Undisclosed Integrator #2
Jan 25, 2015
So before we all jump on Carl, let's look at the help. There is a process of elimination and I certainly would have assumed a lightning strike and replacing cameras seems likely and solved the immediate problem. If the cameras failed due to lightening did the power supplies and cameras get replaced? Just because they work doesn't mean they work correctly. Did someone consider testing the cables against ground using a "megger" to see if maybe the direct burial cable has been damaged? Have we considered the fact that running the cables inside the fence poles could have cut into a conductor creating another source to ground which would induce voltage differences? The new cameras may not have the same transient and surge suppression the original cameras may have had, which Carl stated correctly. At this point I would ask......is this how I would have installed the job to start? What would it take to make it that way?
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Greg Cortina
Jan 25, 2015
Carl, no good deed goes unpunished.
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Carl Lindgren
Jan 25, 2015

LOL. No problem, Greg. The attempts to bait me are a very minor annoyance. The verbiage also reveals that "Undisclosed A" isn't as incognito as the poster would like.

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U
Undisclosed #1
Jan 25, 2015
IPVMU Certified

Nobody tried to bait you Carl, you said before I said anything:

The first instance is almost certainly lightning. Lightning's effect is completely unpredictable - the only predictable thing is its unpredictability. Since both 24VAC and 12VDC cameras failed, likely a surge was induced directly into the video wiring since the voltage regulation in DC power supplies would typically prevent the voltage from exceeding its setting.

Which is, IMHO, erroneous. It is also squarely on-topic, as the OP is trying to determine the cause. Should I have left it have gone unchallenged?

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Mark Bottomley
Jan 26, 2015

Since you mention it is a ranch, are there any electric fences that a horse might push against some metal fence/pole? Might send a nasty shock into the system.

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Alan Dodds
Jan 26, 2015
Hi everyone. Thanks for all the suggestions. I will attempt to fill in more details. The cameras use a mix of 24VAC and 12 VDC power (actually 3 & 3) at this point. Some of the distances are pretty high from the main power/DVR location. I did measure power at the camera locations upon reinstallation and changed 1 AC power supply and replaced a couple of AC to DC converters I used at the camera locations. I changed a couple of power supplies (DC) at 2 locations because the new cameras needed more current. The new cameras were offered to me my the reseller as a gesture of good faith as they were technically better but they are more power hungry and possibly more sensitive, but I don't know that for a fact. I am however getting replacements that are similar to the original ones I had but it might be important to note that after the original "lightning event" back in September, only 4 of the 8 cameras that had to be replaced had been installed by me - the other 4 were from the original installation and were mostly using 24VAC AND of various designs (box/bullet). The steps taken so far is to get replacements that were similar to the cameras I had originally put in in 2013 and to have the ranch owner get an electrician to come and test power issues at the ranch. I'm sure the client will be more than happy to pay for the any additional surge protection so any specifics on what you'd recommend here would be great - Chris, was your recommended hardware installed at the location of the power supplies or at the actual camera locations? Could you share some link(s) to the product(s) you recommend? I would really appreciate it. As far as testing is concerned, I have tested the video lines each time and the voltage output at each camera location."Testing the cable against ground using a 'megger'" is not something I'm familiar with so any additional details/guidelines on this or other possible tests would also be very much appreciated. Finally, there are no electric fences that I am aware of. What would be great is some possibly multi-step solution that would guarantee at 99.9%, given the circumstances present, the cameras are protected: camera location protection, better quality surge protectors with Automatic Voltage Regulation perhaps...? Pretty much anything other than new wire (which would be very difficult labor-wise and probably cost-wise). Thanks again for all the help. It is very much appreciated and needed. Alan
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Brian Rhodes
Jan 26, 2015
IPVMU Certified

'Megger' is a brand of tester, like 'Fluke'. They offer specialty and high-voltage rated testers, but it isn't very descriptive as to what unit or test is actually being run.

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Undisclosed Integrator #2
Jan 26, 2015

I'm not suggesting this exact unit, just the concept of insulation testing.

Megger MIT525 Insulation Resistance Tester | Megohmmeters / Insulation Testers | Instrumart

The concept is that the insulation of the wiring may have degraded due to animals (gofers), weakened insulation from pulling, rocks in ground for direct buriel, etc. It's a lot of work and might not return anything of value.

Here is a link to a manufacturer of surge suppressors for the industry. I can't say I recommend them either, just another option. Isolate at the camera, isolate at the head end, properly ground every device so a single ground source instead of many (if possible).

http://www.ditekcorp.com/product-subcategory2.asp?ProdCatID=17

I wish there was an easy solution that could be guaranteed to work.

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Alan Dodds
Jan 26, 2015

Thanks.

The tester is a significant $ investment. Perhaps I will have their electrician handle that part.

As far as finding a single ground for the whole system, that would be very difficult. There are "remote" locations with power supplies installed nearby (again, original installation design).

For the 6 cameras in question here, power is only split between 2 locations. As a matter fact, managing the video ground loops in the system has been a significant challenge when putting in new cameras. It's been mitigated but never fully eliminated. Thankfully it was already somewhat present and the client has not complained about it.

A camera side protection solution that handles coax and DCV might be the best solution then as it should take care of any abnormal electrical issues anywhere between DVR/Power Supplies and cameras. I have emailed Ditek for a specific product recommendation.

Alan

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Alan Dodds
Jan 26, 2015

I spoke to Bill MacKenzie at Ditek who was very helpful. And these are the products he recommended, though Ditek seems to have many options based on the system/wiring:

DITEK Surge Protection - Products

And at the DVR location:

http://www.ditekcorp.com/product-details.asp?ProdKey=59

and

DITEK Surge Protection - Products

An electrician is on site today so I will post a follow up with what happens.

Thanks again to everyone here.

Alan

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Undisclosed #3
Jan 26, 2015

As a side note, "whatever"-to-fiber convertors can be helpful in scenarios like this. Any time you have a lot of cameras distributed around a property with distributed power supplies as well you can have a risk of all the grounds not being at the same potential. This can cause current leakage in cabling like coax or twisted-pair, which also helps power surges propagate over comms wiring.

Surge protectors will help, but they're not a perfect solution. Using fiber converters for the comms cable gives you absolute electric isolation between the devices. Many of them are fairly cheap these days as well.

Keep in mind, the fiber converters can certainly introduce a new failure point, but if you power the camera and converter from the same power supply and employ a decent surge protector you'll have covered the likely failure scenarios much better than just "lots of copper cable and surge protectors".

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Alan Dodds
Jan 26, 2015

it sounds great but it implies running fiber for my all my video feeds. I'm assuming the cost of the hardware alone is prohibitive for the system I'm dealing with here. Also, running new wiring of any kind would be the last resort based on budget and time. I would still have to deal with isolating the cameras from any metallic mounting location and protect the cameras from issues over the power wiring.

Thanks for the feedback. Never thought of fiber in this application before.

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Undisclosed #3
Jan 27, 2015

it sounds great but it implies running fiber for my all my video feeds.

No, it just means you have a 3foot loop of fiber somewhere.

Yes, cost is an issue, but you could employ this fiber isolation strategy at your current site without having to re-run all the cable.

TC
Trisha (Chris' wife) Dearing
Jan 27, 2015
IPVMU Certified

Or just do optical isolation without any optical fiber at all:

Side Note: In professional audio, ground loops are the devil. Even the smallest differential can cause audible hum in a microphone line because of the high gain used. Because of this, when the MIDI protocol was designed, it was written into the spec that optical isolation was required on every on the input of every MIDI device. Had this not been done, the multipath ground loop scenarios that would have occurred would have been depressing.

i'm not sure what the cost is, but even cheap $100 keyboards have MIDI ports. Maybe analog cctv cameras would have benefitted from the same type of onboard isolation.

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Vincent Tong
Jan 26, 2015

If all the cameras are mounted on metal frames or poles, most likely it is traveling through the metal and inducing to the housing of the cameras. That is probably why you are seeing it fry the camera and not the power supply or the DVR. Insulate the camera mounting with wood or plastic so that the camera's housing has no way of coming into contact with the metal frame/pole.

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Trisha (Chris' wife) Dearing
Jan 27, 2015
IPVMU Certified

What if the pole/box is being used as the camera ground?

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Undisclosed Integrator #2
Jan 27, 2015
Those ground loops may be a piece of the puzzle. To answer your question a good ground is a copper rod driven to a suitable depth based on the soil type. The fence is likely not a great ground.
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Trisha (Chris' wife) Dearing
Jan 27, 2015
IPVMU Certified

Yes, I agree. Also the fact that multiple locations may be electrically connected by the conduit makes a lot of possible paths.

As for the ground, although there are some approaches where the camera ground is floated, generally it seems easier for lightning protection at least, in opting for providing shortest path from induction. Do you agree?

But there are definitely different strategies out there.

@Alan, the way I figured it is you would want the suppression (and ground) as physically and electrically close the the camera as possible, meaning right before entering in. Note that there are different model suppressors required for AC or DC depending. Of course if you want to protect the power supplies you would put it before them, but there would be a small chance of induction between the supplies and the camera in that case.

In any case I think there are more experienced people to answer on this thread than I at this point, so let's see if anyone else has an opinion on it first.

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Alan Dodds
Jan 27, 2015
Thanks guys. I'm definitely planning on isolation all replacement cameras from any metal mounting point at this time. The fiber isolation sounds good, except that there is a chance the electrical issue can come into the system after the device's insertion unless it is at the camera location itself. To be safe one would be needed at the DVR location as well. The Ditek solutions are probably more in line with the budge here. Also I have to consider the fact that if the issue happens again, I might have to replace the protection equipment, so it should remain somewhat affordable. I'm still waiting to hear the results from the electrician's site survey. Then I'll implement the best bet solutions, probably with some degree of redundancy. Alan
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Trisha (Chris' wife) Dearing
Jan 27, 2015
IPVMU Certified

Also I have to consider the fact that if the issue happens again, I might have to replace the protection equipment, so it should remain somewhat affordable.

In the U.S., damage from lightning strikes is usually covered by homeowners and business owners liability insurance. If your client is not, see if they can add it just in case...

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Alan Dodds
Jan 27, 2015

I think they might have used their insurance the first time, but this second time around, there was no lightning involved for sure and 6 of the original 8 damaged cameras went dead.

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Trisha (Chris' wife) Dearing
Jan 27, 2015
IPVMU Certified

Some policies cover power surges as well, although it's rare. However, most policies can be modified or coverage added for non-lightning power surge damage. Ironically, some power companies themselves offer a form of insurance thru a power surge "surcharge".

Also, the power company may also have some incident data related to the surge on the date of the second failure. It might be helpful to know whether the surge came from the grid or was local in origin. Finally, was there any thought to isolating the camera power from the rest of the site by creating a dedicated circuit as soon as possible after power ingress?

Good Luck!

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Mark Jones
Jan 30, 2015

There is some very good advice here. Let me add something please. I saw a lot of this in the Navy. Sensitive equipment on one end of the ship hardwired back to a common point. A vessel is unique in that there really is no ground. The hull is the ground. Ground loops, especially with video, are common.

Your original plan, to isolate the cameras from metal builidings and poles is DEAD ON. Use plastic or molded back boxes, and don't forget the screws/bolts as well. You can find non-metal bolts and screws at most hardware stores. (A quick check method is to use what I call a cheater plug - a three prong to two prong adapter. It will isolate power from ground unless Neutral is being used as ground somewhere, and help you pinpoint your issues, camera by camera). You can't leave it this way, but it is a quick, cheap diagnostic. One on each end, camera power and monitor, and you will be able to see if the bars go away.

As I read this thread I was curious about the quality of the overall video picture with AC and DC mixed on DVR's. It had to be questionable. Factor in what are certainly ground loops and the resulting video quality must have been a "C" at best. I am willing to bet you have some seriously large black bars running on a few cameras, and a ton of half frame video - rolling pictures. Almost no way around it, given your description.

I would certainly insulate the cameras. Ranches and farms are notorious (and have been for years) for having AC power from different transformers at different points. If you don't have a mix of voltages I will be amazed. That difference in voltage is a difference in potential. It does not take a lot to cause your issues. 1-2 volts will cause what you are seeing.

Another idea for you (and the owner) to ponder is this; if you can't bring him to the mountain, take the mountain to him. Instead of recording at one location, put smaller recorders at different points in the field, closer to the cameras. You can still use your existing video wire to run monitors and control back to the home.

I can feel that you are trying your best for this customer, but at some point, you have to tell him the truth. This was a bad plan from the start. There are better ways to have installed it. With prices being what they are for small digital units, I would seriously consider putting smaller, cheaper units in the field, with proper surge protection. You will fix a ton of problems, and he will have a better picture, which is what this is all about at the end of the day.

Good Luck.

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Trisha (Chris' wife) Dearing
Jan 30, 2015
IPVMU Certified

Mark, agree totally that floating the ground is the best way to eliminate ground loops and their resultant artifacts like rolling bars. However, I'm not convinced it's the right thing to do here.

IMHO, of primary importance here is preventing the failure of multiple cameras due to lightning and other abnormal catastrophic surge 'events'. Although irritating and possibly detrimental to the system, ground differences of a volt or two, IMHO, are not the cause of the failures, and can be eliminated when they appear using inline devices. This is not an ideal solution for GL, but is a conscious compromise to better meet the lightning threat.

In your floating ground scenario I assume you still recommend lightning arrestors at the cameras. But this presents a problem in that lightning arresters are normally grounded as close to where they are physically to provide a safe short diversionary path for lightning and other surges.

The very practical question therefore is where exactly does one connect the ground of the lightning arresters in a floating ground scenario?

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Alan Dodds
Jan 30, 2015

Thanks for the additional input, guys.

Ground loops are present but mitigated, usually by minding the grounding point of nearby cameras that share some of the wiring at one location or another. SO the quality is not perfect but no black bars or half frames.

The lightning or inline surge protection components will need to be grounded. Where is a good question. Not to make it a huge undertaking I would use the metal structure (poles/fences/building frames) of the mounting locations. Anything other than that would be a "next step" if required.

I still haven't heard back from the ranch manager regarding the electrician's findings. I've been too busy but I will follow up soon.

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Matt Ion
Jan 30, 2015

I don't know that I have any specific advice that hasn't already been covered, but looking at all the different stuff going on here, I thought I'd share a few of the weird things I've seen.

  • I had one site where I was to replace a failed IP dome camera attached to the Alucobond sheathing of a building (Alucobond is a sheet building material comprised of a light-weight plastic core with thin aluminum skin on either side, making it conductive). I removed the old dome (an IQ-A11), connected network and power (12VDC) to the new one (rebranded HIKvision) and went inside the store to ensure it was working and configure its IP. At that point it was working fine, so I went back outside, mounted it to the wall, went back inside to check the view... and found signal loss.

    Thinking maybe a wire had been pinched, I went back out, pulled the camera off the wall, checked all the wires, then went back inside to check its function - working perfectly. Went out, re-mounted it, headed back inside... signal loss again. ARGH.

    I went through a few other steps I don't recall, until I finally discovered the camera shut down as soon as it touched its metal mounting plate that was screwed to the wall. On a hunch, I pulled out my multimeter... and got a reading of some 40VAC between the camera body and the mounting plate. Something was putting a significant potential into the entire outer wall of the site, relative to the camera's power supply (which if memory serves was a transformer-and-regulator type, which SHOULD keep the power fully isolated).

    In the end, I made it work by cutting out a piece of cardboard to put between the mounting plate and the wall, and rubber O-rings to isolate the screws from the plate, and it's still working today, 3-4 years later. Moral of the story: a potentially damaging voltage differential can exist almost anywhere... and more to the point here, can indicate a far more serious problem somewhere else. And yes, I reported the issue to the site and noted it on the service order for the building maintenance outfit... whether anything was ever done about it, I don't know.

  • I've often had ground-loop issues using video baluns and Cat-5e, and on one site, it finally got to me badly enough that I took the time to figure it out: the problem exists when you put cameras with shared power and video grounds on a power supply with a common power ground for all those cameras.

    The balun essentially puts a coil in-line with the video signal and video ground (two coils, actually, one at each end), which adds a few hundred feet of length to that run, as well as several dozen ohms of DC resistance. When multiple cameras have a common power ground, and a common video ground (at the DVR) that's several times the length and with a lot more DC resistance... well that's a textbook recipe for a ground loop.

    In my experience, the majority of 12VDC-only cameras DO have a common power and video ground internally, whereas dual-voltage AC/DC, and 24VAC-only cameras use an internal rectifier and regulator that isolates the power ground from the video ground.

    That might be somewhere to start for your ground loop problems... not that it's a priority, BUT...

As others have suggested, there may be a causal correlation between the ground loops and the camera failures - ie. the two issues have a related source. One possibility (just thinking out loud) is that a relatively low voltage, say from a leaky power feed to a remote building, is being carried in one of the conduits, and then being carried into a camera mounted to a metal pole... that may then be felt by other cameras via shared video and/or power grounds (or a combination of both!). That potential may not normally be enough to cause an issue, but suppose a power "brownout" (common in rural areas) means an INCREASE in that potential relative to ground, which means a surge fed into the grounds of all those cameras.

Again, this is purely slightly-knowledgeable speculation... but now suppose the original cameras all had solid enough power supplies and video systems to withstand these fluctuations, but those replaced after the lightning killed them do not? That might explain why six of the eight new cameras have subsequently failed where the old ones keep working (note: it might help to know what brands and models both the old and new cameras are).

As for the source of that stray voltage, it's possible the lightning strike damaged the insulation on some of the camera wiring OR SOME REGULAR 120VAC WIRING that is now creating a potential in the metal and then in the camera wiring... that's something for the electrician to sort out, but it's easy enough to test by pulling a camera off a pole, then measure for voltage (AC and DC) between the camera housing and the pole.

Personally, I'd start using all that coax to fish through new Cat-5e so as many cameras as possible can have home-run power instead of power supplies scattered all over the place (with the added bonus of easy IP upgrades later). As has been suggested elsewhere, I'd also look at isolating the cameras from their earth grounds (aka metal poles).

All this, of course, is in addition to the electrician making sure there are no problems with the power source, and adding UPS units where possible to clean up the power going to everything (another benefit of home-running as much power as possible is to get more cameras on the filtered source).

Plus if you want to add lightning arrestors, which by nature need their own earth grounds... maybe THOSE could simply ground to the poles, which by their nature are well grounded. (Note: I've only ever worked once on a system that needed serious lightning protection, so I can't say if that would be sufficient grounding... someone with more experience in that area can correct me if necessary.)

I know it's a lot to read, but hopefully it helps :)

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Alan Dodds
Feb 02, 2015

Thanks Matt.

I appreciate your taking the time to share your insights. Everything is helpful. No steps have been taken yet but I will make sure to follow up when solutions are implemented. I haven't heard from the ranch yet regarding the electrician's findings but will follow up in the next couple of days regardless.

Alan

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Alan Dodds
Feb 03, 2015

So the electric company (APS) sent an electrician who found a "bad neutral" in the ranch's system. He installed a temporary system monitoring device and will report on their 1-week analysis very soon. I spoke to the ranch manager and all-around fix-it man who told me he found a loose and improperly wired neutral in the guest house's panel. It appears that he fixed the "bad neutral" issue and the cause of recurring brown-outs at the RV locations (which apparently was seeing voltage variations between 120 and 89 V!).

Now, the bad wiring has been in place a while now so I'm still planning to remount the cameras fully isolated from the metal structures and posts (I'm not ruling out a stray voltage issue here as well). I will also suggest a quality automatic voltage regulator and UPS at the DVR location (which is where the majority of the cameras pull power from). I will probably hold off on lightning and surge protection at the camera locations themselves as parts and labor makes it a substantial add-on.

I'll post a follow up when I have more info.

Alan

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Matt Ion
Feb 06, 2015

I look forward to the updates!

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