RF shielding the service panel

Hi all,
For the electricians out there:
I recently moved my home office to another part of the house and have discovered a fairly pronounced symptom of RF interference in my pc monitor (occassional wavy lines). Unfortunately the optimal placement of my pc puts it directly above the service panel in the basement and against the wall where the power enters the house.
I could move my workstation to another part of the room but I'm wondering if there isn't something I could do to shield first. I must admit I'm a little concerned about the health effects of this as well.
Thanks in advance,
C.
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ChuckM wrote:

What you are seeing on the monitor is a low-frequency MAGNETIC flux field from the power line wireing, not an RF field. Unfortunately, there isn't any inexpensive and convenient way to shield against 60 Hz magnetic fields. Distance works, and reducing the field (by pairing wires) works. Twisting the paired wires helps even more. As a last resort you might have to buy a shielded monitor - that would be cheaper than installing shielding for the power circuitry.
First I'd try moving the monitor downstairs and seeing if you can locate the exact source of the interference. If you have above ground utilities and the power line isn't twisted where it comes off the pole, that could be one source.
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There is really nothing in a standard computer monitor that would be susceptible to RF interference unless the signal was so powerful that sustained exposure would be dangerous to the human body. And there is really nothing in a breaker panel to generate such RF fields. PCs manage to work quite nicely in virtually every ham radio operator's station in close proximity to powerful transmitters where the perceived danger is that the PC will interfere with the equipment and not vice versa.
I seems more likely that you have an example of magnetic interference. I've seen this sort of interference before where a computer terminal could not be operated at a particular desk in a court office without having the image look like the reflection in a funhouse mirror. I can't remember precisely what the electrican found when he finally tore into the wall beside the desk but it was something like poweful currents being returned through a conduit wall because of miswiring. If your problem is magnetic in nature you should be able to isolate it by turning off breakers to determine where the current flow causing the field is located and then work from there. Rotating the monitor may cause noticeable shifts in the lines. Also, since the interference is only occasional it might be possible to determine what is going on in the house at the time of the interference that is causing it.
--
John McGaw
[Knoxville, TN, USA]
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Let's return to when so many were worried about electricity causing cancer, et al. So the naive (such as local gossip TV reporters) put up pictures of high tension power line towers. Classic of conclusions based only upon speculation. They immediately suspect it must be those dangerous towers without first learning simple facts. You now see an example of the real facts. If AC electric was causing a human health problem, then you now see where that threat was greatest: inside house and adjacent to the breaker box where, both, current is greatest and distance to AC electric conductors is least.
BTW that electric threat was also promoted using junk science. Once the original study's data was obtained, then the conclusion was exposed using flawed statistical analysis.
Monitor is probably suffering from the magnetic fields that are greatest adjacent to breaker box. Not RF interference. Magnetic fields. Many expensive solutions exist. A better alternative is move desk and monitor elsewhere, or maybe buy a flat screen.
ChuckM wrote:

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One thing that I forgot to mention before that w_tom brought up is the possibility of replacing your monitor. If you ditch the CRT monitor and buy an LCD flat panel you will no longer have magnetic field worries. A decent LCD can be had for under $500 and while that may seem expensive it is nothing compared to the cost of buying enough mu metal to shield your electrical service. Look upon it as an opportunity...
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wrote:

Yeah, well I recently exercised that opportunity when I bought a new video card that then "required" I upgrade my motherboard/CPU and RAM. I think I'm tapped out there for now.
Right to all the posters, should've known better. It is magnetic interference. Thanks for the wake-up.
And thanks for the responses. I hoped it'd be something simple like tacking some AL foil up over the service panel in the basement (I'm on the first floor). Guess I better rethink my interior design.
C.
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I had a lab at work that had the same problem. Traced it down to the neutrals and grounds tied together where they were not supposed to be. Check your wiring and make sure that your grounding is up to snuff, less than 25 ohms. My home which I just tested was less than 5 ohms at the service.
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If you are so worried about the health concerns of the magnetic field then maybe you should stop sitting in front of a pc monitor or a tv or holding that phone to your head. Oh yeah scrap the micro wave too. Sorry it just makes me laugh when I hear about the fear of what is comming out of those big bad electric wires but no one ever worries about all those devices that they use everyday that consume electricity
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ChuckM wrote:

In my experience as a computer technician and consultant, the service panel wouldn't be an issue, but the power line entering the house *may* be. Remember that a wire creates a tubular magnetic field around it, whereas a service panel with all its different connections would have a more diffuse and less focused effect. It's the wires and their antenna-like effects you have to watch out for.
But I'd expect the actual placement of the monitor and computer power cables, and the video cable itself, as more likely sources of any problems. Make sure that none of these wires cross or pass too near each other, and especially that there isn't one too near to the rear of the monitor, where the magnetic TV tube is located. Experiment with different positions. In *rare* cases you may want to place the monitor on a power strip leading to a separate receptacle, or use a surge suppressor with isolating receptacles.
At last resort, try moving the monitor to another part of the room. If need be place a dark blue field on the screen and move the monitor around to see what effects you can notice.
Actually, a last resort would be switching to a better monitor, or an LCD screen (unless you're a hardcore gamer).

Shielding is both easier and more difficult than you might expect. Creating a simple Faraday cage between your monitor and the power lines could be as simple as some chicken wire against the wall (you can conceal it behind anything). But completely isolating yourself from interference can be a black hole of maybe this, maybe that trial and error.
http://en.wikipedia.org/wiki/Faraday_cage
The Faraday effect is why buildings with metallic structures can interfere with cell service, even if they have plenty of windows.

Statistical studies show a weak to nonexistent association between power lines and cancer: http://www.mcw.edu/gcrc/cop/powerlines-cancer-FAQ/toc.html#1
There was enough concern in the 80s to lead to thousands of studies worldwide (in other words, it wasn't just a media scare; there were concerned scientists as well), but fortunately, few were able to demonstrate any considerable and consistent danger. The one that is still considered widely applicable is use of old-style computer monitors by pregnant or potentially pregnant women (especially when they sit *behind* a monitor rather than in *front*, as in some secretarial or call center pools), but monitor manufacturers have followed the strict Swedish guidelines for around a decade now.
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