What Killed My CCTV System? Guess Right And Win

I received a call from a customer to say their CCTV system had stopped working, on a very stormy night with strong winds and heavy rainfall, and could I fix it? The problem is now solved but I thought I'd pose the scenario here as a bit of fun to see what others think might have happened. I'll post the solution in a couple of days.

The customer has an 8-channel Dahua HD-CVI DVR connected to 8x HD-CVI 1080p cameras. The power to the DVR, to the attached Samsung monitor and to the 8 cameras is protected by a UPS which provides 20+ minutes of battery power. An ethernet cable connects from the DVR to an ADSL router/modem which is not protected by the UPS.

The customer reported that his monitor was black and he couldn't see any camera feeds on screen. I attempted to remotely access the DVR and found I was able to connect but all the cameras showed black. This meant the DVR was still alive which was good news. I found the DVR was recording black video. Next I went back to the last occasion on which the DVR had recordings from the cameras. Every camera showed similar symptoms. Here is the view from camera 8.

The first second or two show the normal night time IR image. Then the picture starts to break up. What struck me as particularly odd is that parts of the corrupted image cycled through scenes from several of the other cameras, and not just from camera 8. How and why would that happen, I wondered? After a few seconds, the image went black and stayed that way. The same symptoms could be seen on all 8 cameras.

Question: What was the cause of the black video problem and what is the solution? Sorry I don't have any IPVM lanyards to give away as prizes!

I'll post the solution in a couple of days but know there are some members who love troubleshooting and might have a little fun working out the problem and solution. Feel free to ask questions if more information is required.

Luke, thanks for sharing! Great idea!

We'll figure out a prize and some recognition for the first (non-Dearing :) person to solve this.

Thank you John!

In retrospect, I should have increased the drama by starting with, "It was a dark and stormy night ...."

Thank you in advance to all who post answers to this whodunnit. I'll hold off commenting on any responses for a couple of days but look forward to your detective work.

NTSC vs PAL settings got changed?

DVR did not like the square wave output generated by the cheap UPS when the power went off

The Modem and patch cable are good because you connected and stayed connected - Check.

The DVR showed previous playback - Video output is good - Check.

Still have video on the hard drives - Hard drives good - Check.

All cameras showed the same symptoms at the same time - Two things that are common to all cameras at the same time are power and video input card (Unlikely that cable all went bad at the same time).

Unlikely that all inputs died at the same time. Individual cameras dying would indicate a single video input lost on a card. All dying at once, with the same symptoms would indicate your power supply probably blew a fuse or tripped an internal breaker, depending on what kind it is. Power is common to all of your cameras.

- My 1st. guess: since all BNC ports on the DVR's side combine and end in one single daughterboard circuitry, a surge in voltage running through the wire from any camera to DVR (storm and heavy rainfall; lightning strike will find it's shortest way to ground through any piece of metal in the ceilling or conductor wires that are in it's path) simply messed up with the channels and it just "went completely crazy" and that "crazyness" showed on-screen in the monitor. Signals meant for channel 1 showed up in channel 8 and viceversa. And then the first or even a second voltage spike fried either the camera or the daughterboard.

- You didn't say if coaxial cable end-to-end, or ethernet Cat.5/6 cables with video baluns were used in this case. If it is ethernet network cable with video baluns, consider yourself "luckier" if the VIDEO BALUNS sacrificed themselves ($12 dollars or less a pair, way much cheaper to replace than any DVR or camera) by taking the surge strike themselves and protecting the more expensive components by frying it's own (meaning the BALUN´s) internal circuitry.

- The camera view from the video you uploaded seems to be an indoor scene. If the camera's bracket was drilled directly to the wall inside the house, the wall's material typically will either conduct electricity very very poorly or none at all. You didn't say if the camera is installed touching or near a metal beam. If that is the case, then my guess is the voltage surge used the beam as a path to the camera; and continued to the DVR.

- My 2nd. guess: the customer simply did "something", which could be anything you can imagine. (In my years of experience in the field, many cases involve finally the end user themselves). They touched or clicked or disconnected something they were not supposed to, and when they messed up and cannot undo it, they call you to say "it just happened and now it is like that" : (.

P.S. By the way; I've seen that more than 90% of customers have the perception that simply adding a UPS battery will solve all their power backup (in case of a power outage blackout) and surge supression (in case of a hight voltage spike) problems. But maybe (partly because of the great marketing job some manufacturers are doing, partly because we integrators ourselves simply throw-in a UPS to the project for this purpose without further thought) that solution will only give them a sense of false protection / flawed peace of mind, because if the UPS doesn't cut off the voltage spike NOT ONLY COMPLETELY but also AUTOMATICALLY 100% of the time, or burne itself, or burned it's integrated fuse, then the UPS is simply an expensive 6 outlets power strip providing a couple minutes of extra power.

Hi B, thank you for having a go. In answer to your questions:

1. yes, coaxial cabling was used to all cameras.

2. The camera was not touching or near a metal beam.

3. The customer did not fiddle with the equipment at the time of the problem. The DVR setup is just off-camera and I would have seen the customer in the video if they had walked over to the DVR.

That's interesting information about being overly reliant upon a UPS. In this customer's case, the mains power is unreliable with semi-regular blackouts and power surges. So far, the UPS has done a great job at smoothing out the power reaching his CCTV system.

One big clue must be the time stamp which goes from :13 seconds for the opening scene on View 'A' to :19 seconds for View 'B' and then continuing to oscillate between forward and backward time stamps. Since we assume these CVI cameras don't keep time individually but rather only one time is kept on the DVR, this time-traveling interleaving seems perplexing.

However any good mystery watcher knows that seemingly unimportant facts like 'the ADSL modem not being connected to the UPS' are key. Therefore that plus the fact that it seems well nigh impossible for a sequential stream to have frames anything but appended, no matter what the source, indicates that the NTP connection was possibly syncing and freewheeling as the connection to the Internet was lost. Perhaps in the waning moments of power, the video threshold voltage dipped and resurged causing the cameras to re-order themselves in their dying gasps?

Actually I have no idea.... :)

Luke one question is one about how specific your solution is, i.e. does your explanation account 100% for all weird behavior, without fail? Could you replicate this failure at will?

Can you post another camera's clip before going black? Also when you say the Samsung monitor was black and the views were black, do you mean the monitor was off? Do these cameras keep their own time and create their own overlays? I would think not, but who knows?

Hi C,

Thank you for your detailed reply!

Here is another clip before the cameras went black.

"My solution" simply got the customer's CCTV system back up and running and doesn't account for the weird video prior to the cameras going black. That's why I only posed the question about what was the cause of the problem rather than why the weird behavior was seen. As the customer is remote from me, I don't know if I could replicate the failure at will as I would need to be onsite to perform that test reliably.

Your question about the Samsung monitor is a good one. When the customer said the monitor went black, that wasn't quite right. There was still the basic grid or matrix of where the cameras should appear on screen along with the overlays including the camera name and the time stamp. However the video was just black. The cameras do not keep their own time. The time is provided by the DVR and the DVR provides the overlays.

Thank you for your probing questions!


I don't know but I'm hoping it involves bears.

Are you using an offline UPS?

DVR and CVI cameras were out of sync when the power outage happened. (swithed to battery power with inverter)

Hi D, yes, the customer is using an offline/standby UPS.

Time stamp and camera overlay continues to work(this overly is not coming from the camera), therefore the Hisilicon DVR chip was encoding and storing to disk properly. The reason you are seeing multiple cameras on "one" channel is that the video input to the Hisilicon DVR chip is getting confused - it gets multiple interleaved channels from the HDCVI video decoders into its video port(s). The DVR chip is intermittantly losing synchronization. So now we've isolated the problem to the HDCVI decoder chips. So either they have gone on "walk about", or something from all the cameras have caused all the decoder chips to lose their minds.

The analog portion of the DVR (the video decoder front ends, which connect to the cameras) should have a common ground connecting the DVR and cameras (but they should have some ESD/Lightning Strike protection diodes). Additionally, the analog portion of the video decoders will have a common power and ground plane that is DIFFERENT than the digital power/ground planes that the Hisilicion DVR chip uses.

So my supposition is either a) lightning strike messed up the common ground between cameras/DVR or b) power spike affected only the analog power/gnd portion of the DVR, causing the HDCVI video decoders to stop working.

Either way, the fix would be a simple reboot of the DVR and cameras (assuming nothing was damaged). If, however, the analog power/gnd portion of the DVR got toasted, you probably replaced the DVR?

It is *possible* that all eight cameras got damaged, but I don't think so.

Robert, with regard to the overlays, is it correct to assume that there is only one system clock? Not time on each camera, just the Dvr? If so, even with a haywire walking cpu, why would the overlay time jump around, back and forth?

Also the overlay for camera # stays on camera 8, indicating that the confusion happened before that overlay was imprinted but after the time overlay, no?

Hi Robert,

Thank you for your insight. That's very interesting information about the weird video and I greatly appreciate it.

I did remotely reboot the system but the cameras remained black.

Remote rebooting might only do a soft reset of the DVR chip. Unless you power-off the entire DVR system, you won't reset the HDCVI video decode chips, and they might remain scrambled.

Anxious to hear what the REAL problem was, and how you fixed it.

It's still possible that the cameras themselves are not damaged, only the DVR inputs, right?

Though I am thinking that yours and B's Lightning strike guess is looking more likely all the time.

Btw, re the overlays, the time on the overlays changes when the 'other' camera scene comes into view, sometimes there is as much as 7 seconds difference, then it goes back when the scene switches back. This back and forth continues thru the first 2/3 of the video, which each seperate 'clock' advancing its own time. It's hard to catch at full speed, you have to scrub it to really see.

Good point Robert! When remote rebooting didn't help, I did ask the customer to power off everything and then power on again but the problem remained. Mind you, it's amazing how often that does solve problems :-)

The DVR chip will have only one clock. It will place the same timestamp on all channels if it is turned on. It can be turned off if each camera is providing its own timestamp - but HDCVI probably doesn't have time metadata in their analog stream yet, so you set up the DVR to provide the camera number and the timestamp.

From what I can see in the video, the overlay is not from the camera, it is generated by the DVR chip. I see the timestamp change from bright to dark (called Alpha-blending) depend on the background, but I don't see the actual timestamp jump around - it counts forward from 21:49:13 to 21:49:28, with maybe some jitter to it (could be how Youtube plays it or how it was uploaded).

The label "Cam 8" is also probably generated by the DVR chip - labelled when setup accured. This stays consistent regardless of what scene is shown, telling me the video is getting mixed up prior to the DVR chip applying the timestamp. The timestamp typically happens after the video is captured, but before it is compressed using H.264.

So I still think something is wrong in the HDCVI decoder chips and their sync/connection with the DVR chip or the cameras.

Of course, I could be wrong...

Hey Luke, can you confirm or deny Robert's and B's lightning theory as the cause of the blackness, as well as Robert's cold boot as the solution?

They both seem most plausible, but if they were ruled out then that might inspire a new round of wildly speculative and highly entertaining scenarios. ;)

Hi C, I like your mischievious spirit!

Cold booting was tested and did not resolve the problem. I do not believe lightning was a factor. The customer was asleep so I cannot totally rule it out. However I reviewed video recordings on all outside cameras for the 20 minutes prior to the camera blackout and could not see any illumination caused by lightning. There was only torrential rain and high winds.

The possible scenario may be as follows

(a) It appears that the power source for camears and DVR are different. Thus the power supply was intact for DVR and the power supply for cameras might have got disrupted

(b) The breaking of the images may be due to short circuit and the time intervening between tripping of MCB and fluctuation in the voltage.

(c) Another possible cause may be due to lightening strike the Power source for Cameras.

As brought above I feel the black out of cameras may be due to complete disruption of Power supply.

Capt Ravinder

My guess is that the power went out, the system then kicked onto UPS only. The UPS voltage then went low scrambling the cameras. Cameras kicked off first (IR uses more juice). Then the monitor was using minimal power (only displaying the minimal DVR frame and black leaving even more battery power for the DVR to hang on (which was using nearly nothing as processors are idling). Then possibly the DVR was powering the modem through the network port (unless modem was on another circuit that stayed alive and it was somehow powering the DVR? or the DVR itself is POE?) Solution: hit breaker which tripped in storm or wait till power company crawls out of bed). It seems in the video there are no devices powered on in the house (no appliance LEDs lit up in frame that I could see anyway).

I posted this a half hour ago or so I thought.

Ok, I'm gonna go for

  1. Power outage
  2. UPS kicks in for 20 min IR starves camera chips as UPS fails
  3. Cameras go black
  4. Power comes back on with a surge, damages UPS
  5. Bad power from damaged UPS still runs DVR, but cameras can't sync/genlock
  6. Solution: Disconnect UPS, run power directly to devices...

My guess is the video card. My experience when we used DVR's was whenever I heard or saw "camera bleed", (Camera 3 showing up or blinking when viewing camera 1) it always turned out to be a video card issue. The old Integral units I used this happened when the card wasn't seated properly or was about to fail. Even happened on new units the card would get jolted in shipping.

If that's not the case my second guess would be some strange power issue with that brand cameras.

I am going to vote for a short in the monitor or associated cable. I have experienced this before and replacing one or the other solved the problem. Disconnecting the monitor from the recorder restored remote images to their proper display.

I have also seen the recorder itself take a surge and exhibit similar symptoms and the recorder had to be replaced.

My guess would be water leaking into a camera connection and shorting the 12vdc to a video input - fixing meant disconnecting inputs one at a time until shorted input lifted.

Firstly, thank you to everyone who joined in on this whodunnit. It has been fascinating to read so many different approaches to solving the same problem. Some of the responses were quite detailed and a lot of thought went into them. While I posted this just as a fun challenge, I've also learnt a lot from the many knowledgable contributors, especially about the inner workings of a DVR to explain why the video went so weird.

And the winner isMark Jones! More about Mark’s answer in a moment.

What was the cause of the problem?

The cameras were all supplied power by a single AC/DC power adapter which was connected to a UPS. The AC/DC power adapter died with only a few seconds of warning so all the cameras stopped working. The green LED on the power adapter was no longer lit so this made it easier to confirm the fault.
The DVR had its own power supply so it kept working and simply recorded black video.
The monitor had its own power supply and was working despite the customer saying that it had gone black and wasn’t working.

What was the solution?

The solution was simply to replace the inexpensive AC/DC power adapter.

It’s difficult to say why the power adapter died. It cannot have helped that the electrician, who originally wired power to the cameras, mistakenly thought they used AC power. There is a green LED on the power adapter and it switched off when camera power connections were connected with the wrong polarity. It’s possible this shortened the life of the power adapter although I was more worried about the impact on the cameras at the time! It was this same LED which helped confirm that the power adapter was dead.

The Winner

Not only was Mark Jones the first member to identify the failure of the power supply to the cameras as the likely cause of the problem but Mark’s detective work was elegant in its logic and simplicity. He identified the components making up the CCTV system, and systematically eliminated all that he could from being a cause of the problem. He narrowed this down to one likely candidate and he was right. Congratulations Mark!

Challenges in solving the problem

In retrospect the problem and solution are simple enough but there were a few challenges to finding and confirming the problem.

  • The customer site was remote from me so I could not just drop in, check out the equipment and find the problem myself.
  • The customer was non-technical so my troubleshooting questions needed to be straightforward with no jargon.
  • The customer did not speak the same language. I suspect the reference to the monitor going black may not have been an accurate translation. While I always take note of what customers tell me, I also try to find ways to verify the information they give me without causing offence! In this case, I was able to use Skype video to see the DVR interface showing on the attached monitor but all camera feeds were black.
  • It was unclear if lightning was involved in affecting the CCTV system as the customer was asleep at the time. I checked the camera recordings for the 20 minutes before the camera blackout and found no evidence of illumination by lightning so I ruled it out as a probable cause.
  • I also wondered whether there had been a general power outage but as the customer had been asleep, no outage was noticed. By taking remote control of a computer at the customer’s site, I was able to access the admin interface to the customer’s ADSL router/modem and check it’s “up time”. The admin interface showed the modem had been connected since well before the camera blackout event and was still connected. Given the ADSL router/modem had been working the whole time even though it was not protected by the UPS, I ruled out a power outage or power spike as a probable cause.

By ruling out some nasty scenarios, it quickly seemed likely that the cause was limited to internal problems and not caused by outside influences. Asking the customer to check the green LED on the cameras’ power supply rapidly confirmed the simple cause of the problem.

I get a kick out of solving technical problems when they happen and I hope you’ve found this fun too!

Wow, eight cameras on one power supply. Maybe one like this?

Congrats Mark! Thanks Luke!

Hi C, yes, exactly like that. That's a good picture. Thanks for posting it!

The power adapter had plenty of spare power beyond what the cameras required so I wasn't concerned about overloading it. I had considered using two power supplies with 4 outlets on each supply. It has some merit but also adds some complexity. Given the non-technical nature of the customer, I figured it was better to install a simpler system and leave a spare power adapter if ever it was needed, especially after the original one had clearly been tortured by the electrician. Explaining (via the translator) which component to replace was a simple matter and the CCTV system was back online very quickly. A spare adapter has been organized just in case this should ever happen again.

Aaahh, the power brick.

Sadly the weakest link in way too many security systems.

Sadly the weakest link in way too many security systems.

What 'weakest link' do you prefer? ;)

Thank's Luke, it was a fun exercise. To be honest, I did not notice that the first post was a video. I thought it was just a picture. Once I watched it I began to have a few doubts but decided not to let electrical goblins change my mind. As my reward, I will post one back. We had a good one recently.

Thanks everyone!

Mark, congratulations! Luke, thanks for doing this - it was fun!

We'll recognize the both of you in Sunday's newsletter blast and I'll contact you both individually to see what other bonus we can give the two of you!

Hi John, thank you for your recognition. That means a lot to me.

If Mark is the winning troubleshooter, I guess that makes me the troublemaker.

Hi Mark, that's fantastic and I'm sure everyone will look forward to your technical challenge! Hopefully this is just the start.

I was just reading yesterday on ways to make physical security a more fun topic. There is very little out there. Everyone is so serious! This "tech-challenge" is a good idea Luke.

what is the power supply Ampere ?

and this problem on morning only or morning and night?

Hi Mohammed, that's a good question! The power supply was rated 5 Amps which was more than enough for all 8 cameras at maximum power usage. The problem occurred day and night.

Mohammed, It was only first noticed last Thursday morning. Given the nature of the actual problem, it was morning and night. Other doors locks from the same power supply functioned normally.

Hi Mark, I think Mohammed was asking about the first CCTV tech challenge on this page and not your new and improved Tech-Challenge #2 :-)

  • you can use power supply more than 5 amper and test again
    or use this power for 3 cam or 4 and test
    when ir enabeld in night the camera used max amper .

Hi Mohammed, while one can always use more powerful power supplies, the existing one had been running well for a year so I have no reason to believe a more powerful unit is necessary. If this was a new installation, then I would also wonder if a more powerful power supply should be used. However the camera load on the power supply was well within the specifications of the power supply.

What exact model CVI cameras were they? Several IR ones that I see are 7.5 W, which is the right at the Mendoza Line for 5A power supplies. ;)

A spare adapter has been organized just in case this should ever happen again.

Either way, why not use both the 'spare' and the production one together, with 4 cameras on each, to take a load off, so to speak?

What exact model CVI cameras were they?

Hi C, the specs of the power supply adapter are 12V DC, 5A, 60W.

Six of the cameras were model HAC-HFW2200E which each need a maximum of 4.5W.

One of the cameras was model HAC-HDW2200M which needs a maximum of 6W.

One of the cameras was model HAC-HFW2200D which needs a maximum of 8W.

Therefore the total maximum required power is 41W. The power adapter can provide almost 50% more power than the most demanding scenario required by the eight cameras.

why not use both the 'spare' and the production one together, with 4 cameras on each, to take a load off, so to speak?

One could take that a little further and use individual power supplies for each camera so that the failure of any one power adapter would only affect one camera. If the setup was mission critical, that is what I would do. However I considered the following in choosing to use a single power adapter for all 8 cameras:

  1. The customer is elderly and not technically inclined.
  2. The customer is remote from me so I can't just go on site and fix the problem.
  3. The customer does not speak the same language as me which means any troubleshooting advice has to go through a translater which can cause meaning and details to be lost in translation.
  4. The power adapter was rated well in excess of what was needed under a worst case scenario. There was no need to take any load off.

For these reasons, I chose to keep the setup as simple as possible. The customer only had to find and swap out one power adapter rather than having two or more power adapters to sort through. Working out the probable source of the problem took only 10 minutes. The time to get the cameras back online was almost an hour due to having to talk the customer through the solution via a translater. I was quite happy it only took 1 hour to fix a remote residential CCTV installation and deal with a language barrier.

By the way, just thinking about your question of splitting the HD-CVI camera power load over two power supplies, would you use two 4-port PoE switches to power 8 IP cameras or would you just use a single 8-port PoE switch?

By the way, just thinking about your question of splitting the HD-CVI camera power load over two power supplies, would you use two 4-port PoE switches to power 8 IP cameras or would you just use a single 8-port PoE switch?

Luke, I wouldn't have said anything except that you said you were going to have TWO power supply units on-site, a working one and a spare, and you had not posted the camera models nor their power usage yet, so its only natural to consider using both, even if under the max power draw of one.

Still if I had a power supply that was running at 'almost' 70% capacity, and I had another in a box at the site, I would certainly consider instead running them both at 35% to extend their life. Also, if one died you would still have 4 cameras that would continue to function, instead of the whole system being down until the user notices and performs the swap out.

In the case of dual-use power, instead of swapping out an old unit, the user would just transfer the 4 from the one to the other while waiting for a replacement.

Of course they both could go at the same time (lightning, surge), but then one would expect to have other failures as well (DVR power, UPS) that would prevent the system from functioning at all. I'm not saying its defintely the way to go, but its worth talking about right?

One other thing about the power Luke, how long are those eight 12v runs? And what gauge wire are you running them on?

Thanks for making me think with your insidious challenge!

you had not posted the camera models nor their power usage yet

I had thought this question might have arisen while the challenge was open. However it was only open for 2 days so maybe it wasn't open long enough to reach this level of questioning.

Still if I had a power supply that was running at 'almost' 70% capacity ...

The cameras are not constantly running at 70% of the power adapter's capacity. That 70% figure is based upon on the most demanding conditions. All these cameras have Smart IR so they vary their IR output depending upon available light. Secondly they are only running at 3fps. 70% is a safe maximum load and the reality is it's going to be significantly less than that figure and I'd rather keep an unused power adapter as a spare so as not to shorten its life. The simplicity of the system was a key requirement which outweighed the need for some of the smart options you have proposed. For a different kind of customer, I might well have chosen to implement it with the two power supplies as you have suggested. And yes I am glad you raised it because it is most definitely worth talking about and thinking through. Thank you for raising those ideas!

how long are those eight 12v runs? And what gauge wire are you running them on?

I wish I knew! The house had been prewired with coaxial and power cabling. Given the dimensions of the house, the cables could not have been any longer than 100 feet. The cabling was questionable and the electrician's termination of cables was a great source of concern to me. The fact that the whole system has been running so smoothly is a testement to the robust nature of HD-CVI technology. I remember when IPVM first reviewed HD-CVI and mentioned it worked perfectly even with poorly terminated cables, I was overjoyed as I knew this should give me a reliable solution for sites where I did not have the option of installing new cables myself.

Thanks for making me think with your insidious challenge!

"Insidious: proceeding in a gradual, subtle way, but with very harmful effects." I was thinking that was all OK until I got to the harmful effects part ;-) Thank you for putting a lot of thought into your questions and asking some of the questions that hadn't been asked before.

Luke, unfortunately it is not enough to simply add up the power requirements of all the cameras and buy a supply based on that alone. You need to take into consideration the power dissipated by the power cables themselves due to their resistance, as well as the effects of the resultant voltage drop on the equipment.

This amount of loss depends on multiple things, three key ones are:

  1. the length of the cable (longer=more loss),
  2. the cross-sectional area of the conductors (smaller=more loss),
  3. the voltage amount and type (lower=more loss)

Based on what we know, I would say there could be significant loss in transmission.

BTW, 24v AC has far less loss, this is why it's typically used in cctv. It also explains, (though does not excuse), your electrician's initial confusion. Many CVI cameras are 12-24 dual-voltage, are yours? I'd rather not speculate too much on what the effects are, without knowing the lengths and the gauge, but you absolutely could be pushing the power supply to the edge, And it did die, right?

It's possible also that the cameras continued to function fine but the IR was starved a bit. You might not notice this. To know for sure you will have to measure the draw, preferably each camera individually, though you can get a rough estimate by measuring the AC inlet power using a consumer kill-o-watt device, that you could send your client.

There are many voltage drop calculators on the Web you can use to estimate as well. I have a 4amp brick that I can play around with and I will report back.

unfortunately it is not enough to simply add up the power requirements of all the cameras and buy a supply based on that alone ... Based on what we know, I would say there could be significant loss in transmission.

Hi C, this is a good point and would definitely have stirred the debate during the tech challenge. Power loss is a given but as the house was new, and did not rely upon ancient cabling, I believe the cables themselves were of reasonable quality even if the workmanship on display was of concern. I can't prove this either way but I doubt that power loss lead to the short life of the power adapter. The documentation with the cameras only indicates that they accept 12V DC. The power adapter really was dead and wouldn't even power a single camera during the day time.

I've used the same kind of power adapter elsewhere and they are still running fine. Of course, every installation is different so it's hard to compare with this case. I believe the power adapter to be a good one but some failures can be expected. That leads me on to a bit more of this story.

I was asked to provide a 5 camera solution for this home with 4 cameras outside and 1 camera inside. Therefore I chose an 8-channel DVR. I had very rough information to go on so I took several types of cameras with me totalling 10 cameras. Some had different lenses and some had more powerful IR. I had to carry the DVR, 10 cameras, a UPS, 24" monitor, power adapter, power connectors, tools and more because this kind of equipment was not readily available at the destination. Getting all this equipment through customs was interesting!

When the customer found out that I had 10 cameras, he said that's what he wanted! I explained that he could "only" have a maximum of 8 cameras as that's all the DVR would support. The power supply for the cameras had been based upon being overly generous for the 5 cameras. So too had the UPS. However increasing the camera count to 8 and using some of the more powerful IR models meant the allowance was no longer as generous as it could have been. In addition to the spare power adapter, I ended up leaving the 2 spare cameras with the customer in case any of the cameras failed. So far that hasn't happened.

It will be interesting to see how long the replacement power adapter lasts. Next time I'm over there, I'll investigate the power usage and loss further. Thank you for your ideas!