Floating the ground will almost certainly stop any and all ground loops caused by the mains. I' ll leave it to othes to explain why it would be the incorrect method of solving the problem?

Alan

Ok, Ok, but whose splitting hairs anyway ?I was just trying to give a general explanation, which I have to do alot, since most of this is way over the heads of a lot of the electricians I have to deal with.

A question on the last couple posts..... I have a system that has the said horizontal line problem, however floating the ground on the projector and running the projector through a panamax line conditioner does nothing for the lines. I have isolated the source of the lines to my 4 Zone Lutron Grafik Eye, which when turned completely off the line are gone or when turned completely on the lines are barley noticeable. However, when the system is set to dim the lines make the system unwatchable. Can someone provide some guidance on how to resolve the problem? I have read the above post, and understand it to and extent, but I dont know (yet) which "phase" (i.e. "leg") my lights and equipment rack are on. They ARE on seperate breakers but I dont know anything beyond that. Any input is greatly appreciated!

Alex

I second that. rigid conduit if you want any rejection.

It is worth repeating that none of these things completely stop signal ground loops. The question is have you reduced the voltage flow to a point where it is no longer causing a problem. If you've done your work properly and the induced voltage is still too high then you bring in an isolation transformer.
For the cost of the Jensen cable TV isolation transformer I think it's a good idea to spec one into every job. CATV is where probably 99% of my problems come from.

For the person with the Lutron problem. I don't think that has anything to do with ground loops. You may want to contact Lutron tech support to see what they have to say. Panamax has many levels of product, what you are using may not have enough filtration to deal with the crap the lutron seems to be putting on the line.

Alex,

Are all four zones on the Grafik Eye configured for the correct lamp type? Do you have any low-voltage loads with electronic transformers on any of the zones?

? Who installed your graphic eye? What’s your total load per each graphic eye zone? Are you dimming incandescent, electronic low voltage, magnetic low voltage lighting, or heaven forbid -florescent?


I have never seen a graphic eye crap out, however, you must keep in mind that you cannot go over 600 watts per zone, you can drive magnetic low voltage directly, but not electronic low voltage without a special booster. If you are driving an electronic load that is burning out, you might get some really weird RF in your electrical. I guess what I am saying is it is probably one of your fixtures that is causing the problem.

I most certainly have seen this although I have no idea technically what is happening. I describe it as a dirty netural. I will bet that at least one of the loads on the Graphik Eye are low voltage. I think we either went the route of an isolation transformer or we used a power conditioner like the Triplitte LC1200.

[Link: tripplite.com]

I suspect it was the power filtering that did the trick.

Alan

David, Im not sure what you mean by configuring the Grafik Eye, I am not aware of any changes you can make to the unit itself, just different modules that are connected to it for different loads. To the best of my knowledge there are no low voltage loads.... 1) 4- Can Lights, 2) 4- Wall Sconces, 3) 2- Step lights on the riser, and 4) Rope lights in the soffitt. I was not working this job when designed so I don't know if the step lights or rope lights are low voltage, but I doubt it.

RTI, I hooked up the Grafik Eye after the electrician installed his switches. My loads are listed above, my total load per zone is probably no more that 250W (~65W floods X4). And again I'm not aware of any low voltage lighting, and certainly not florescent.

Alan, I confirmed with the other system designer that the rope light is NOT LV, so the only zone in question would be the step lights that the electrician installed. I can't imagine them being LV, but i'll look into it. That aside, moving the lighting to different phase/leg in the panel wouldn't fix the issue?

And can you fill me in on the tripp lite piece?

Any other input is welcome! Thanks!

How about a good grounding system for the cable system. I have had problems in the past with not having a good ground on the cable system. I line conditioner is great to have also, but does not remedy a virus like humbar. It must be dealt with in the beggining not at the end.

How does the pictures look if you are only watching a dvd??? Good? Or is it just bad when watching cable only?


BNC

Sure you can get 120 volt rope light, but there is also a lot of rope Light out there that is run off of a transformer.


Pull the graffic eye out of the box and disconect each zone one at a time to see if the problem goes away, of course you should de energize the system first each time you do this. But this will probobly lead you to your solution the fastest.

I know that a lot of electricians like to split the electronics systems when they balance the panel.

They already have a pretty good idea on how to balance the HVAC load, appliance loads, receptacles, lighting loads, etc. from years of repetition...

So all of that happens just like normal, and then they just split these extra receptacles for the electronics system, and they are done!!

Simple!! But wrong.

My #1 recommendation is to find an experienced and open minded electrician in your market who is also very familiar with high performance a/v systems and not just a hard headed contractor who thinks he is always right because he has a card in his pocket. (It's too bad Larry isn't Nationwide)

RTI has you on the right track;

One of those loads is causing noise from or through the Grafik Eye. I'm also highly suspicious of the rope lights, because they usually are low voltage. Even though someone said they aren't, don't trust them totally. The step lights might be LV also. Make sure none of the cans are flourescent.

Once you verify the actual load type of each load and reference Grafik Eye's capabilities, you might have the source of your problem. Find out the actual type of lamp in the fixtures and make sure they're acceptable to the Grafik Eye.

You may need to trace further; if your video source the cause of the problem? Is the Grafik Eye on it's own breaker or shared with the projector or video source? That would be bad mojo.

Great informative thread guys.

I think dealing with the Graphik Eye is besides the point. There is no filter you are going to be able to put on the load that will eliminate the interference. I think that it is a better idea to deal with the consequences than seek out the source. And when you discover the offending load what will you then do? Filter the mains supply to your equipment and you will, in all, probability solve the problem.

Alan

doesn't phase me

The Grafik Eye set-up menu defaults to incandescent and magnetic low-voltage transformers. It has another selection (for each zone) for neon (cold cathode), Fluorescent and for electronic low-voltage. When you are dimming electronic low-voltage transformers from a Grafik Eye you need the remote-mounted ELVI-1000 Interface AND you have to configure the Grafik Eye for an electronic low-voltage load on that zone.

Another question:

Are there any control interfaces connected to the Grafik Eye via the Class 2 PELV terminals on the Grafik Eye that also connect to any of the A/V equipment? Such as the GRX-RS232 serial interface? If so, this may be causing a ground loop from the electrical service to the Grafik Eye to the interface to the A/V equipment and back to the electrical service.

You can also try changing the branch circuit for the Grafik Eye to the other "leg" in the circuit breaker box. That may solve the problem.

Good luck!

By the way, the sconces could have electronic transformers in them, too. What kind of lamps (bulbs) do they have. These electronic transformers are tiny and light weight and easily overlooked. The step lights could be compact fluorescent which (sometimes, depending on ballast type) requires a completely different interface for the Grafik Eye, a different configuration in the set-up menu and a special ballast!

One last thing for everyone:

It's FLUORESCENT. Easy to remember:
"I've got the FLU"
"I'm mining iron ORE"
"I've lost the SCENT"