UTP ground loop issue, suggestions welcome!

[humanparody 0]

This will be my first post, and first cctv(wired) so be gentle

 

The problem I am experiencing on this fresh install is what I am assuming are 60cycle bars (white bars slowly scrolling up the screen).

 

I bought the system about a year ago after a neighbor's house had been broken into and had not done any research prior to the purchase other than it seemed like a reasonable price for a decent amount of features. The system is a Q-see DVR with 4 cameras included (yes...yes....I know)

 

So, the guy was caught and the cameras sat a year until I got bored. Upon settling on the best location for each of the cameras, it became clear that I couldn't make the 60' cables go the 525' I needed and so began my research on how to make it work. Luckily I have a friend who does security systems for NSA and he got me pointed in the right direction with UTP and baluns. unfortunately he is currently unreachable so he I am.

 

Enough back story, here's the specs:

3 cameras mounted in trees, 2 on one tree approx 325'(wire length) from the house(DVR is here), and the third is another 200' away, running from the same wire.

 

The wire is cat5e unshielded, and is in conduit from point to point...water tight, I could pressurize it. Along with the cat5 is a seperate 18-2 for power(direct burial irrigation cable...this is my real profession).

 

The cameras are 12vdc, and after running the voltage drops for each camera, I realized that 18-2 would not cut it. My solution was a Honeywell HPTV2404-E which is a 24VAC(25.5 actual), 4-output(each fused at 3A, and a 5A main secondary fuse).

 

To provide 12vdc to the cameras I purchased 20-36vAC~DC to 12vDC adapters located at the cameras. As best I can tell, the power end of things is functioning as designed..23ish VAC at the input, 12vdc coming out of the output while the cameras are on and using IR.

 

I am using passive baluns, made by APEC, model ATP-1A, with built in transient surge protection.

 

The cable drop can be divided into sections.

Starting from the DVR:

cat5e and 18-2 for 325' to junction boxes(two single gang outdoor boxes sitting side by side connected by a 1/2" conduit 6" long.

 

For the 2 cameras in this tree, I used the supplied 60' cable to run down the tree in a plastic conduit.

This cable is a single solid wire in the middle and contains a yellow(video+), shielded by stranded wire(-), and red(+). The ends splt into two terminations for power and video, both sharing the same ground. I spliced the baluns in one box, and the power converter in the adjacent box.

 

I know I will get flamed for this next part, but I didn't know any better. I cut the cat5 at this box and continued a new run along with the 18-2 to the next tree 200' away. I used a plug and jack rated for cat5e and only had the blue pair continue, as the green and brown were used for these two cameras, and the orange still remains unused.

 

In this second 200' leg I also ran another 18-2 as a spare....so to sum up, in this conduit, one cat5 with only the blue attached at either end and two seperate 18-2's(one carrying power, the other not attached to anything)

 

I wired things differently for this last camera. In the single gang box at the ground, I used the 24/12 adapter and pulled out the orange pair(coming from the camera) to carry the 12vdc 20' up the tree to the camera, I severed the green and brown pair, and left the blue untouched on its route to the camera(fool me once.....) and the balun is enclosed in the tree mount box.

 

Only thing that I would consider out of the ordinary on this run up the tree, I encased the cat5 in 1/2 copper(approx 20') for both vandalism resistance and that it blends into the tree once it turns brown(this tree is at the end of my driveway next to the road). The bottom of this copper does extend 6" into the ground before it switches to pvc. It is also anchored at several points with stainless mounting hardware.

 

I used the same tree mounts for each camera, which are aluminum junction boxes with a brown powder coat, typically used for landscape lighting, but hold the camera just the same and are discreet. These are also mounted to to the tree with stainless stand-off bolts to allow for growth.

 

OKAY...that was a long read, right?

So here is the issue:

 

I was unaware that ground loops existed until I saw them on the screen...did research...found the most probable cause...and applied said solution.

 

Obviously I realized the potential to have a seperate ground where the camera case contacted the aluminum enclosure, which on one tree was securely screwed deep into a tube of water with leaves.

The other was secured to the tree AND a perfect grounding rod(copper pipe, forehead smack).

 

What I have done thusfar:

I seperated the camera on the far tree from its enclosure with a 2" PVC nipple and made sure nothing metal inside came in contact with the inside of the juntion box. I also made a small PVC transistion from the copper pipe before it entered the junction box.

 

I checked to make sure that all the other junction boxes had no contact with any of the splices.

 

I have yet to isolate the 2 cameras on the first tree from their enclosure, but as you will see in a minute, it wouldn't have helped anyway.

 

 

Here is the weird issue I can't figure out. If I disconnect the plug/jack for the far camera(power still continued on through 18-2), the 2 close cameras come in loud and clear(only the SLIGHTEST of bars that are completely livable...that I attribute to the tree anchors.

 

If I disconnect the baluns for those two trees(power still connected), the far camera comes in loud and clear(no bars at all, perfect picture)

 

BUT, if I have all three connected at the same time, terrible bars on all three, and the far tree is almost at the verge of dropping out completely.

 

I have checked the polarity, voltage, soldered all wire connections(except the plug/jack), made sure I didn't untwist any pairs beyond the 1/2" needed. I have individually checked each camera feed with a balun and portable TV while the others were connected. The video is fine on the portable TV, while the other two would show terrible bars back at the house.

 

I even tried completely diconnecting the power and cat5 from the first 2 cameras, and wired in the spare 4th camera on the ground, and made absolutely SURE it was not grounded anywhere.

 

As soon as it is connected, the clean signal from the last tree goes to crap as well as the spare camera(which also works fine if I disconnect the plug/jack for the far tree)

 

On a side note, just to be sure you have all the details, I have the DVR and the Honeywell box plugged into the same surge protected power strip. I connected the 18-2 to output 1 and left the other 3 open since I was only drawing like 1.5a on a 3a circuit.

 

I have tried reversing the 24VAC connections into the converters in every combination, and the results are exactly the same.

 

As best I can tell, my cameras are "floating" and the only ground is the plug the power strip is plugged into.

 

Just a quick note on environmental factors. The 200' run to the last camera runs along side the power line that feeds my house, before it hits the transformer. It is a good 5'+ away, and since that camera when attached alone actually has the cleanest signal, in my mind at least, it has been ruled out(but what do I know)

 

From the house, the conuit runs about 3' away for a 10' section next to my Cable TV lines(2 of the thick black coax lines that they use these days laid together) and then later on just before it reaches the first tree it passes 8' away from the transformer feeding my house(200 amp service). There are no other potential sources for interference that are in the ground, and at the DVR/location, there is a 42" flat panel display(same power strip) and cable box(same power strip) in close proximity. But again, I can get a clean signal from one tree or the other, but not both, so I ruled out all of these as the cause(but what do I know).

 

 

 

 

 

 

I am lost, as you can tell by my first book "DO NOT TRY THIS AT HOME".

 

If you have read this far, I applaud and thank you. What am I missing?????

 

Thanks in advance for ANY information you can offer.

[ilk 0]

I would suspect you are getting cross talk on the CAT5 cable.

 

Try getting hold of some good quality cable (no joins) and run it on the ground between first the furthest camera and connect using the existing baluns.

 

I would guess that this clear up the camera signals.

 

Your option is to then either run a new cable to utilise two CAT5s or to try to minimise the cross talk interfernce by remaking all joints & connectors maintaining the twist to industry specs. A following move would be to upgrade the baluns to a higher quality active units perhaps with opto isolation.

 

Ilkie

[humanparody 0]

Ilkie,

 

I appreciate the reply. Although you would certainly know better than me, I wanted to add a little more info on tests I tried last night.

 

I added my fourth camera, which was on a completely separate run of cat5 in a different location(this attached to the house). This one, like the others, works great on it's own. If attached at the same time as ANY of the other 3, it as well as the others get the lines.

 

It seems the only two that work together at the same time are the two that are connected at the first tree. One thing that strikes me as the probable cause for this is the cable lengths coming down the tree are exactly the same length(measured them out on the ground) as well as their path back to the DVR(Cat5 and power).

 

I was reading some other threads on similar problems and read that the problem with common video/power grounds on cheap cameras when used with baluns is the two separate ground paths of different resistance that it can take which create a ground loop within the wire itself.

 

I don't know what action though is allowing the two close pair to work without a problem, but another one at a longer distance on the same cable introduces a problem if used at the same time, and yet another on a completely separate cable does the same, but all work fine alone.

 

I have connected a battery powered monitor at the DVR and had a perfect picture on the two close cameras on the monitor, and a clear picture on the portable unit for the far camera. As soon as I touch the ground of the far camera to the DVR connection, I get bars.

 

It seems if I measure out an identical length of cat5 that runs from the 2 harmonious cameras to the far camera and put in in the line to add the extra resistance that the 3rd camera has, then they should all 3 work harmoniously like the 2 do now.

 

The cat5 I have already so that is the free option if I could get some consensus that it would work.

 

The only other option I have is I guess some sort of ground seperation at the DVR, which I was also looking for suggestions on. I've already dumped too much money into this so the cheaper the better.

 

It would need to be a solution for the house mounted camera that is on a separate cat5 run and is PoE, and the single blue pair(farthest camera). It seems that on separate grounds at the DVR, everything is happy.

 

Also, and this is just for curiosity sake, what exactly are these 20-36VAC to 12VDC regulated adapters that I am using. I can't help but think that they are similar to what is in a 25VAC camera that everyone says don't have ground loop issues and thr maybe I can utilize them somehow to resolve this issue.

[Blake CCTV 3]

Sounds like you need some video isolation transformers these are basically an evenly matched transformer that allows the signal to pass without the physical connection thus keeping the earths separate you will need one on each camera that has noise on it. Try them at the DVR end first although sometimes they work better at the camera end.

[Blake CCTV 3]

Just another thought this may be a pain but worth doing remove all of your cameras and connect them to the DVR locally all of your pictures should be fine.

[humanparody 0]

Okay, update. Got the 4th camera working with the first 2. Only the far camera is having an issue at this point. I wanted to know thoughts on the following wiring scenario.

 

Since the loop is forming because I have two grounds(power and video) of two lengths(one on a line from each twisted pair, and one of the wires of my 18-2).

 

What would be the harm in simply using BOTH wires(or even just one really) from the 18-2 for (+) and allowing the (-) from my pairs to serve as my only ground? It is basically that way anyway right, seeing as the power ground is already connected to the video ground at the camera?

 

I know the obvious solution is to power the cameras individually, but I'm stuck with this first run as I only have the single 18-2 in the 325' house to first tree run. It would be almost impossible to pull a new 18-2 in the conduit.