Ground Loop challenges

General rule of thumb. Only one power source. Only one ground point. A IR drop is created between 2 grounds. If between buildings, where power could well be out of phase with the power a of another building. The safe bet is either RF or fiber.

john

I do remember about 7-8 years ago using a device from ConnectorsPlus out of Miami for a large camera job. It was a 16-port ground-loop unit for the dv r end, where all the camera wirings went into it. It did come with individu al cables that went into the dvr. Then, at each camera there was an individ ual unit. That was when we still used coax, now only shielded cat5. Hope th at helps you.

Is this coax or cat 5 using baluns? Are the cameras 12vdc or 24vac? Are you using a single power source or individual power sources for each camera?

Doug

Sorry, I forgot to mention that important info, brain was not totally activated.

There is a single power source 120vac for everything with two 16 channel

A few cameras are 24vac but most are 12vdc with a step down inverter at those cameras.

Cabling is Siamese Coax RG59 w/18-2.

As I said above my understanding was the problem is due to an imbalance in voltage at 60 cycles or ground reference between phases from the power company.

But then of course I have to question that since I am on a single power outlet or only one phase of the incoming AC.

Thanks for any input.

Les

I don't know much about this subject but I was under the impression that a "line conditioner" would isolate all those kinds of problems out of an AC power source. NO ?

Hi Jim,

I have been researching this most of the day. What I have found out the only real choice is the single BNC Ground Loop Isolators, which is what I have been using. It seems that mfg's don't think it is worth the effort to put them in a full patch bay of 16 channels. I have given up on my quest for this thingie.

Have a good week.

Les

This might provide you with some useful information. You may want to call them also for their expertise. Toll Free: 877.843.3921

E D,

Thanks for the link!! Very informative!!

Based upon what I assumed and now I am more convinced that the cheap 16 channel power supplies that came with this "donated" system to a "non-profit" may be the biggest part of the problem.

I need to do some math to determine which is more cost effective. Replace the (2ea) 24vac power supplies or load up more Ground Loop Isolators on the system. Very quickly I am thinking the Isolators will win.

Thanks again!!

Have a great rest of your week.

Les

I thought an inverter turned DC into AC. I had bad luck with those AC/DC converters on cameras a while back, and never used one again. I have used several cameras that were AC DC auto switching internally that seemed to work just fine, so maybe I just had cheap converters.

I did try a fairly expensive multi tap ground loop isolator at the DVR once a long time ago. It worked but all the camera feeds were grey and dim. Loop termination on and loop termination off at the dvr. Both were the same. I went to cheap single line ground loop isolators at the cameras after that and they seem to work just fine.

Hi Bob,

I guess maybe the term "inverter" could be the wrong term for this device and you are most likely correct that an inverter is changing DC voltage to AC voltage.

Maybe the correct term that should have used would be "converter" where the voltage is being converted from 24VAC to 12VDC.

In some respects it may just be which side of the Continental Divide you are standing on. :-)

As things always seem to go nuts at the worst possible time, I am presently having a problem with one camera that seems to be blowing the "converter" at the camera. It is either the camera is pulling to many amps when the IR kicks or something like that. It is a new camera and still under warrantee. I just ordered another and before I install I will be taking some volt/amp readings so I can compare values. Also ordered some new "converters" since I am out of stock.

Have a good weekend.

Les