one of those Balun / UTP and Ground Loop threads

[CraigVM62 0]

I went back a few pages to see if a thread addressed this question and didn't find any so I hope it is worth starting a new one.....

 

In a nutshell, I have an installation with 2 structures approximately 250' apart linked with a dedicated low voltage conduit containing 2 Cat-5e cables dedicated for the CCTV system. One structure "House" has the DVR , power supply and a number of cameras while the second structure "Pool House" will have 3 cameras. One cat-5e will be feeding the remote cameras to the DVR and returning DVR monitor back via passive baluns .

 

Both structures have independent electrical services so my concern is grounding issues.

Would the safe thing be to use the second Cat-5e to feed power to the cameras in the remote structure ? My CCTV distributor has tried to convince me that ground loop issues are never a problem when using baluns over UTP.

 

I would like to install a power supply on the remote structure which will allow me to save the second run of Cat-5e for future expansion. Luckily I have the options of changing from one to the other depending on what works best, but it is nice to have an idea what to expect from others experience.

 

A few details include that the conduit is only 1" and also contains a couple other Cat-5e and Coax runs for Data, CATV and Security. No room for running RG-59 for CCTV

 

Thanks

[Soundy 1]

Actually, the biggest cause of ground loops with baluns *is* a central power supply, at least when used with basic 12VDC cameras that have a common video and power ground. Separate power supplies - including those in separate buildings - should avoid the cause of the issue. Dual-voltage or 24VAC cameras tend to avoid the problem as well, since the cameras isolate the power and video grounds internally. To be safe, make sure the cameras' bodies aren't attached to anything grounded. You might also find it preferable, if you are using DC power supplies, to use transformer types, rather than switching models, as the transformer provides physical and electrical isolation from the source.

 

My CCTV distributor has tried to convince me that ground loop issues are never a problem when using baluns over UTP.

Your distributor is delusional But with good cameras at least, it SHOULDN'T be a concern.

 

One other thought: if you're using 12VDC-only cameras with common video/power grounds, and a shared 12VDC power supply, in the pool house, then you may still see ground loops... again, the solution is dual-voltage or 24VAC cameras.

[CraigVM62 0]

Matt,

 

Thanks for the replay....

I regret the cameras are 12 volt only. I am not certain I know how to identify a Transformer type vs. Switching power supply

 

At the house where there are 7 cameras, I had planned on using a 9 channel power supply such as this

 

 

In the pool house with only 3 cameras, I was going to use a "brick" 12 volt 4 amp regulated power supply as used to power LCD Monitors. I typically pigtail out inline fuse holders so each camera has it's own fuse. Am I correct in this would be a Switching type ??

With as cheap as they are, I could easily install a 4 channel PS like the photo above instead.

 

If I did have to power the remote building cameras over the second Cat-5e I would have used the "brick" power supply while still putting the inline fuses at the other end.

 

Luckily all cameras are mounted onto siding or soffits so not grounded.

 

Thanks for taking time to help !!!

[eos 0]

First time poster.

 

I figure since this scenario is very close to the job we just did, I'll post in this thread. 16 chan ICrealtime Max Dvr is located in a large metal structure used for storage of cars and has 7 cameras with no ground loop issues, the remaining 9 cameras are located in a horse barn (all metal) located 300 feet away using 3 Cat 6 cables plugged into 4 channel passive balun units.

 

Power supply at remote structure is a 12vdc 18 channel power supply. Using test monitor at DVR, connecting only to the bnc outputs on the balun unit, there is no issues. Once connected to DVR, there is black hum bars moving up the screen. Installing ground loop isolators on these 9 cameras at the DVR eliminate most of the issues. However there is still wavy picture quality on some of the cameras. No interference from PTZ control and all PTZ functions work great.

 

I temporarily used a 3 prong to 2 prong adapter on the DVR and Power supply to see if that helped. It did a little. I do know that this horse barn is powered off the main house electrical panel and the "Car" Barn is off a separate transformer from the main street power.

 

The question is what should I do? The cameras in the horse barn are 4 12vdc PTZ's and 4 dual voltage Nuvico bullets and one remaining 12vdc ir dome. Should I screw some wood to the metal behind each camera and mount them to that to isolate them from the structure? Or maybe take an extra cat 5 run between the location and twist all wires together and ground it to the power supply can and the DVR? Or ditch the 18 chan power supply and use separate plug in transformers for each camera? These metal building jobs are making my hair gray.

 

Any help would be appreciated. Thanks in advance.

[Soundy 1]

It sounds like a ground loop typical of using a central PSU and common-video-and-power-ground cameras with baluns... if so, using separate adapters for each camera would clear up the issue. What make/model cameras are these?

[bongofury 0]

agreed.

Separate power adapters on each camera will isolate this.

[eos 0]

Update, noticed problem on the 4 Nuvico bullets got way worse while coincidentally I was pre-wiring a guest house on the same property. No issues on the PTZ 12vdc units (case must be insulated from electronics) and 1 LTS dome(insulated on top of 4x4x2 plastic box).

 

So I disconnected all 4 dual voltage Nuvico bullets and did try separate power supply--no help. I finally screwed the base to the lid of the 4x4x2 j-box (I should have done this at the beginning) and all issues disappeared Since it was a horse barn, the ugly gray j-box was no big deal, however getting some sort of good looking insulator under the camera could be difficult for those residential jobs.