Colored Electrical Outlets

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On 9/23/2010 8:34 PM, snipped-for-privacy@snyder.on.ca wrote:

The problem with switchers is what happens when you have a lot of them on a power system. Building transformers, especially those for office buildings have been redesigned over the years to cope with the asymmetrical loads from switching power supplies. Heck, these days noise tolerance is designed into the darned integrated circuits themselves.
TDD
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On Sep 23, 8:34 pm, snipped-for-privacy@snyder.on.ca wrote:

Not necessarily. Boards today aren't as ugly RF wise as they once were. Boards sold to the public (outside systems) must pass an FCC compliance test that only allows 6dB for the case. Even at the worst case, 6dB above the limits, it's hardly "radiating RF all across the spectrum".

T-R packs, yes. Linear supplies, not as much.

Poorly designed ones, yes. Ones that haven't passed conducted emissions tests, perhaps. There are specs for these things too.
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wrote:

Specs yes, but virtually no compliance enforcement. Loads and loads of noncompliant crap come into the country every day - with compliance stickers prominently displayed.
Like I said - I spent 5 years in the computer manufacturing business, and what DID NOT comply was a whole lot more common than what did, component wise.
To make a SYSTEM compliant with non-compliand components is possible, but quite difficult.
We used 4 layer boards even back then - with built-in ground planes in the critical areas - and often the difference between a system that passed and one that didn't was as simple as different PLASTIC on the case front - or changing suppliers of the video card - which had the same part number, and supposedly the same design.
One plastic has RFI coating on the inside, while the other didn't. One vieo card supplier had left off the "non-critical" despiking capacitor or other EMR suppression device - and "might" pass with a well sheilded and ferrited cord to the monitor, while the other, slightly more costly, fully populated board would pass, hands down.
When the accountants started running the company instead of the engineers, all hell broke loose when it came to certifying new models.
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On Fri, 24 Sep 2010 13:22:09 -0400, snipped-for-privacy@snyder.on.ca wrote:

Not unless someone complains (usually a competitor).

Sure, but irrelevant.

I've spent >35 years, most of which was spent designing this stuff.

Wrong! You clearly don't know what you're talking about. PCs have special dispensation. As long as the components are listed (at the 6dB tightened spec) the computer doesn't even need to be tested. Many DO NOT have any shielding at all; all perfectly legal.

It *very* few exceptions, ground planes go EVERYWHERE, not just in "critical areas". Power planes, too. Eight layers (4S4P) was our standard card 35 years ago, motherboards had even more signal layers.

Sure, the PS/2s had a conductive coating on the inside (for ESD as much as for RFI). There is no need for much of that anymore.

That's somehow supposed to be surprising?
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On 9/23/2010 10:10 AM, snipped-for-privacy@aol.com wrote:

OH MY GOD! That computer is soooooo old! 8-)
TDD
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On Sep 22, 11:43 pm, snipped-for-privacy@aol.com wrote:

Funny. IBM uses these outlets in their facilities so the noise wouldn't be coupled back into the mains (also on separate circuits so the cleaning servies wouldn't trip anything important).
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wrote:

Not any one I worked at and I was all over the country. There may have been a few people who installed them but they were not using the IBM Physical Planning manual.
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On Sep 23, 4:29 pm, snipped-for-privacy@aol.com wrote:

They were in every building I worked in. They were up and down the halls, even. Cleaning crews were instructed to use them exclusively.
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wrote:

Old legends die hard. I was an Installation Planning Rep in the 90s and I still ran into people who swore IG was necessary but they were not in the IBM Physical Planning community and it certainly was not in our specs.
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On Fri, 24 Sep 2010 11:34:38 -0400, snipped-for-privacy@aol.com wrote:

Like I said, this was in the lab buildings.
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On 9/23/2010 4:18 PM, keith wrote:

Wasn't it at a hospital in someplace like Bulgaria where the cleaning lady was unplugging ventilators in patient rooms to run her vacuum cleaner?
TDD
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