12vdc cameras and baluns ?

[renz05725 0]

Post subject: Re: Ge security systemPosted: Tue Jun 15, 2010 12:36 am

 

I see you posted this on TrailVoy.com too

 

The third is to use twisted-pair cable like Cat3, Cat5e or Cat6, running the video over one pair using baluns on each end, and power down the other pairs.

 

Since you're using 12VDC cameras, you probably want to avoid the balun method, as that will probably lead to ground loops and all sorts of signal quality problems. So then it just becomes a question of what cables are available and/or cost-effective to you.

 

Soundy or anyone else that feels they can answer.

 

Soundy responded to a question about cabling methods earlier this year and had the above mentioned statement about 12vdc cameras and baluns. Can you explain to me why there is a problem with ground loops and signal quality. Would there be polarity issues as well?

 

The reason I ask is simple. We install all of our systems with rg59 cable (siemese) with power supplies that have dedicated fuses for each output. We do this because we do not want to have any issues with quality of pictures or power issues to the cameras. Obviously going with rg59 over cat5e/6 is way more expensive, as well as using the compression connectors over 45 connectors.

We are seeing our competitors going with the cat5e and balum method more and more now. They are able to keep prices lower, as you can buy almost 3 boxes of 1000ft cat5e cable for what you'd buy 1 1000ft spool of rg59. At the same time though I am seeing them struggle with quality of picture, power issues and I've heard some of their technicians discuss polarity issues.

 

Are they using the wrong cameras when going with the cat5/balun method? If going with this method of installation, what factors should be looked at when deciding on cameras, dvr and power supplies? I have heard the distance isn't to big of a factor when using cat5e/6 cable. Is that entirely true?

 

I am the owner of a small Telecommunications and Special Systems company. We have been in business for 2 years now. Originally I was a IT administrator and moved into the commercial sales and led me to this path of where I am now. I have been selling surveillance systems for about 4 years now (thru my company and my previous employeer). I like this site, because it is very informative and allows us to get information we need and learn from what others are doing. While going thru older, posts I ran into your response Soundy and it fasinated me enough to want to know why 12vdc doesn't work well with baluns and cat5/6 cabling.

 

Thank you in advance for any responses.

[Soundy 1]

The ONLY issue I've seen using baluns, that can be specifically ascribed to the use of baluns (that is, not an issue that is caused by something else or could equally affect regular coax installations - like EMI, power losses, etc.) is the introduction of ground loops when using cheap 12V cameras that use a common ground for video and power.

 

First you need to understand what a ground loop is:

http://www.epanorama.net/documents/groundloop/basics.html

 

A ground loop in the power or video signal occurs when some components in the same system are receiving its power from a different ground than other components, or the ground potential between two pieces of equipment is not identical.

 

And what it does:

 

A ground loop occurs when there is more than one ground connection path between two pieces of equipment. The duplicate ground paths form the equivalent of a loop antenna which very efficiently picks up interference currents. Lead resistance transforms these currents into voltage fluctuations. As a consequence of ground-loop induced voltages, the ground reference in the system is no longer a stable potential, so signals ride on the noise. The noise becomes part of the program signal.

 

To understand how a balun creates a problem, you need to look at the design:

 

 

Each side of the signal goes through several hundred or thousand transformer windings, which effectively adds a few hundred feet to the signal path. So a 100' run would translate into several hundred feet of actual wire, with added resistance.

 

Now cheap 12V cameras typically have a single ground connection for both video and power; the cabling just splits that out into two wires, but if you look inside, you'll find the grounds both tie to the same point. But where both runs normally end up being about the same length (usually within a few percentage points) when you have separate coax and power lines, you now have one ground connection that's a few hundred percent longer than the other, with suitably higher resistance.

 

This isn't a problem if you just have one camera connected, because you don't have two ground paths to the same point... but once you start connecting two or more cameras, you start getting all kinds of multiple paths with widely varying resistances, since a camera will have one path to ground via its own power wire, and another path via the other camera(s) - that is, it finds an electrical ground through the its signal ground, then through another camera's signal ground (since the cameras' signal grounds are all tied together in the DVR), and then through that camera's power ground back to the power supply.

 

I've found that you can usually get away with two cameras on one supply with minimal noise, but more than that, things start to get really weird - I've had it where some cameras cleared up and others got worse as the number of cameras increased.

 

So, there are a couple ways around it. One, you can use separate power supplies (ie. wall warts) for each camera. Or, you can use a power can with electrically isolated outputs (rare and expensive). Or you can add ground-loop isolators to the signal lines, which insert a transformer to break the physical electrical path.

 

Better cameras with built-in power regulation, including dual-voltage and 24VAC cameras, avoid the issue, because the power and video grounds are electrically separated - the power ground just goes into the regulator/rectifier and is not tied to the signal ground.

 

Edit: this is also only an issue with passive baluns - active baluns electrically break the signal lines, so using one or both active should avoid the problem as well.

[shropna 0]

Or use passive baluns only on camera side

At "center" side use active twisted pair receiver, with isolated inputs.

Actually, i'm never use passive baluns at "center".....

[rory 0]

I used 2 major american brands of "cheap" $25 Baluns and the quality was awful, never done that again.

Otherwise, the price part does not add up since the baluns themselfs will bring the price higher than using coax.

[renz05725 0]

so active baluns would fix ground loop problems even on cheap 12vdc only cameras?

 

I see baluns priced as low as $9.99 a pair to $29.99 a pair. Now paying more doesnt always mean better, but what i guess would I look for in a balun, if your saying that cheap baluns are the cause as well?

[shropna 0]

so active baluns would fix ground loop problems even on cheap 12vdc only cameras?

 

I see baluns priced as low as $9.99 a pair to $29.99 a pair. Now paying more doesnt always mean better, but what i guess would I look for in a balun, if your saying that cheap baluns are the cause as well?

Not only active. Inputs should be isolated.... Like this:

http://www.nvt.com/content.php?type=product&key=862&cid=root

[renz05725 0]

I went on google and youtube toget a little more info and found a company that says that brown white is industry standard for video signal and that all other pairs must be used for power if u expect the camera to recieve the correct voltage. How true is this? Also coming from an IT background our primary cable is always blue white and then orange, green and lastly brown. I would have assumed that would have been the same here. Soundy seems to put the same in his example to me. R these guys wrong in their standard or is it a simple open base conne t as you prefer standard when it comes to color code on cables?

[Soundy 1]

I went on google and youtube toget a little more info and found a company that says that brown white is industry standard for video signal and that all other pairs must be used for power if u expect the camera to recieve the correct voltage. How true is this?

I've never heard of an "industry standard" for this. I use blue for video, orange and green for power, and leave brown for a spare (future video, RS485, or if a little more power capacity is needed).

 

Most jobs, two pairs are fine for power, especially if you're using 24VAC (current draw is half that of 12VDC; thus, voltage drop is less). Plug the numbers in this calculator and see: http://www.netkrom.com/voltage_loss_over_cat5_calculator.html

 

Also coming from an IT background our primary cable is always blue white and then orange, green and lastly brown. I would have assumed that would have been the same here. Soundy seems to put the same in his example to me. R these guys wrong in their standard or is it a simple open base conne t as you prefer standard when it comes to color code on cables?

It's completely arbitrary; there is no published "standard". You can use whatever pairs make sense to you. For me, orange and green were the most "power-like" colors; blue being the "center pair" on an RJ45 connector made it seem like a logical choice for video. No reason to go that way other than aesthetics.

 

"Cheap" baluns are not a contributing factor, per se. General passive balun design is 1/3 of the issue, coupled with cheap 12VDC camera design, and common-channel power supplies. No one part of the equation is necessarily a bad design, it's just a matter of three particular design concepts that don't get along.

 

Expensive passive baluns will typically have the same issue; cheap baluns generally work fine with dual-voltage or 24VAC cameras. Using individual power supplies with each camera bypasses the problem, too.

 

Otherwise, the price part does not add up since the baluns themselfs will bring the price higher than using coax.

The baluns we use cost $8-$13/pair and work just as well in my testing as the $35/ea. baluns. My cost analysis is based on listed retail prices for Cat5e and RG59, which both cost the same at this particular store; I'm pretty sure our wholesale cost is a good bit less on Cat5e than on RG59. Add the cost of power wire, and the gap narrows even more. Reduced labor costs easily tips the balance in favor of UTP.

 

Keep in mind, baluns will work over just about any wire, every bit as well as they do over Cat5e. I've run video and power on 22/4 Station-Z wire without a problem. They work on Cat3. They work on speaker wire, line cord wire... you name it. If it's ONLY about cost, Cat3 should cost about 1/3 of Cat5e. Station-Z is even cheaper.

[rory 0]

Keep in mind, baluns will work over just about any wire, every bit as well as they do over Cat5e. I've run video and power on 22/4 Station-Z wire without a problem. They work on Cat3. They work on speaker wire, line cord wire... you name it. If it's ONLY about cost, Cat3 should cost about 1/3 of Cat5e. Station-Z is even cheaper.

 

i definitely dont recommend anyone use telco wire for CCTV. (aka Station-Z) Thin cable that can be cut with a butter knife.

 

Anyway, Im not a fan of Baluns and Never will be, cant afford the time to send them back again, and will always go Coax over that unless the application calls for amplified video such as long distances and then I would recommend something in the line of NVT active.

[Soundy 1]

Keep in mind, baluns will work over just about any wire, every bit as well as they do over Cat5e. I've run video and power on 22/4 Station-Z wire without a problem. They work on Cat3. They work on speaker wire, line cord wire... you name it. If it's ONLY about cost, Cat3 should cost about 1/3 of Cat5e. Station-Z is even cheaper.

 

i definitely dont recommend anyone use telco wire for CCTV. (aka Station-Z) Thin cable that can be cut with a butter knife.

As opposed to Cat3/Cat5e - 22ga. vs 24?

 

Anyway, Im not a fan of Baluns and Never will be, cant afford the time to send them back again, and will always go Coax over that unless the application calls for amplified video such as long distances and then I would recommend something in the line of NVT active.

Okay, we get that you're stuck in the 80s down there, technology-wise. For the rest of the developed world, it IS actually a valid option.

[rory 0]

Okay, we get that you're stuck in the 80s down there, technology-wise. For the rest of the developed world, it IS actually a valid option.

Get out a bit and you will see not everywhere is as backward as you think they are.

You have a preference for cat5 and telco wire and baluns, well not everyone shares your opinion and they are certainly up to speed with the latest technology, in most cases more than you are. Personally, I feel coax is for CCTV and it is still the Industry standard, but I wont tell you that you are doing something wrong by using cat5, thats your preference and whatever works for you is fine.

[Scruit 0]

I'm using cat5e and passive baluns. Longest run is about 200 wire feet to the camera. I'm swapping all my old coax to ca5e/baluns because I made the mistake of running rg6 first time round. 7 of my 17 cameras are on cat5e now and I am not having any problems so far.

 

Another reason for the swap is that my DVR is a hybrid DVR/NVR so I can add IP cameras to it. The ca5e that I'm running terminates at a patch panel in the CTV closet punched down to industry standard. When it comes time to go to IP cameras all I need to do is cut off the baluns, put an RJ45 on the camera end and add the POE I'm ready.

 

I'm also taking this opportunity to run the cables better. No more black coax stapled to the ceiling of the garage. All hidden.

[rory 0]

No more black coax stapled to the ceiling of the garage. All hidden.

i only use white coax

[Scruit 0]

No more black coax stapled to the ceiling of the garage. All hidden.

i only use white coax

 

 

No pink?

[renz05725 0]

My whole reason for this thread is not to start an argument, but to look at a potential change for this new year in the way we cable some of the systems we install. We ran 32 cameras at a local buisness here and ended up purchasing 9 boxes of siemese cable at $150 a box (1000ft spools) which if you do the math is roughly $1300 in cable alone. If we had done it in cat5e the cable would have been roughly $600, so there is a $700 difference there. Thing is, we took out 8 cameras from this building that another installer had put in which were all run with Cat5e and baluns that looked like CRAP! The cameras looked goldish green at the dvr with the refresh lines going up and down each view on the cameras. The average run was about 400ft, but we had some cameras at 630 ft.

 

I didn't want to take the chance on this job and put in cat5e cable and have to pull it, because it didn't work for me, the way it hadn't work for the previous installer. So we ran siemese cable with 2 16 channel power supplies and the cameras look picture perfect. Which is what all our customers want and for the most part lets me know all systems are go and the install was a success. If we had run a cat5e cable to the cameras that were 630ft away, would we have had a power problem? What type of baluns need to be used for that type of length?

 

I really want to look at cutting cost this year and it seems one way might be to go from siemese to ethernet based cable on our surveillance system installs. But I want to make sure we know what we are doing before we do anything, because I am not a fan of having to do anything twice and spend twice the amount of $$$ on re-work.

[Soundy 1]

Thing is, we took out 8 cameras from this building that another installer had put in which were all run with Cat5e and baluns that looked like CRAP! The cameras looked goldish green at the dvr with the refresh lines going up and down each view on the cameras. The average run was about 400ft, but we had some cameras at 630 ft.

I've seen a baluns-and-Cat5 install that looked like that... installer used baluns at the camera end but not at the DVR. In fact, rather than use baluns or terminate his runs in BNCs, he actually snipped the BNC ends from the octopus cable and hardwired the Cat5 to it. Solder and heat shrink, mind you... for all the time and effort he put into those connections, he ended up with crap picture for not doing it right. Moral of the story: baluns work IN PAIRS.

 

If we had run a cat5e cable to the cameras that were 630ft away, would we have had a power problem? What type of baluns need to be used for that type of length?

Depends on the cameras, and their power requirements. A 24VAC camera with 200mA current draw would see a drop of about 1.5V at that distance, using two pairs of the Cat5. If it's a dual-voltage camera, that should be no problem, as it's designed to accept input as low as 12VDC (and some of those I've seen will actually handle voltages down to 9VDC).

[rory 0]

Thing is, we took out 8 cameras from this building that another installer had put in which were all run with Cat5e and baluns that looked like CRAP!

That was my experience with well known branded baluns.

[renz05725 0]

Soundy these where Digital Watchdog Cameras and yes they are dual voltage cameras. Actually they are fairly decent priced cameras with great output from my experiences with them.

 

rory, Im not sure what type of baluns they used, I'm pretty sure we have them in the boxes we took out of that site. But I guess part of the problem is they used cheap Hawk-I security cameras and some CHEAP video card that was installed on a PC that was used on a daily basis for work related operations as well. In all honesty the original installer simply didnt know what they where doing at all. It was the electrical contractor that thought it be easy to pick up that work and the low voltage network cabling as well in his contract. Only thing is, you have to know what your doing when picking up either one of those types of work and they didnt. We got the clean up work and full new install on a bigger surveillance system and the testing and recabling of the voice/data cabling which was GREAT!