I once watched the construction of a Tempest-class area: * Commercial metal studs * One layer of metal-coated 5/8" wallboard on each side, metal out * Tape seams with metal tape * Another layer of metal-coated wallboard, seams shifted four feet * Tape seams with metal tape * One layer of regular wallboard for the finish surface * Speakers to play music inside the walls * Motion detectors to detect motion inside the walls
They did the ceiling after the walls closed in, so I didn't get to see what happened there, but I'm sure it was equally impressive.
So long as there is any kind of "connection" a fault will start an arc that will "trip" the CB.
I was installing some foil insulation on a wall with a outlet box. The foil just brushed against the hot wire and FLASH, POP the breaker tripped. I guess the foil had been grounded by another outlet's plaster ears.
Isn't this in the FAQ somewhere? There is no absolute standard, but IIRC red or orange indicates that the outlet is on the UPS system (aka back-up battery/generator system), so it will still keep working when the lights go out. So that is where you want to plug the ventilator and such into.
The shape of the slots indicates the 'heavy duty' outlets. The little side leg on one slot means 30amp, IIRC, but it goes both ways, and normal stuff can also be plugged into there. Numerous web sites have diagrams, if you are curious enough to Google them.
The shape of the slots does not indicate "heavy duty", it indicates the outlet's electrical charicteristics, like voltage, amperage, phase. There are numerous types and shapes of 30 amp outlets, as well as outlets of every other amperage
Furthermore, color of the outlet in computer centers and other locations can indicate isolated ground - a design the reduces surge impact on sensitive devices.
Orange indicates an "isolated ground" receptacle.. The ground pin is a separate insulated ground that goes directly to the panel instead of being grounded to all the other grounds and metal boxes and conduit along the way like the normal ground. Causes less electric "noise" in that particular ground for some electronics that might be sensitive to it.
Per the wikipedia article (FWIW, of course): Color code
The color of a device does not identify the voltage class or power system for the device. Since the colors are not regulated by national standards, the purpose of color-coding a receptacle is set by the building owner. Brown, ivory, white, almond, grey, and black receptacles in the 5?15 configuration are selected to blend with the decor of a room.
Blue receptacles may indicate built-in surge suppressors. * A red receptacle may indicate a special-service outlet such as one connected to an emergency standby power source. * At least one manufacturer makes a yellow receptacle which identifies it as corrosion-resistant. * A receptacle with a green dot is a so-called ?hospital grade? device; such devices are tested to survive harder use than wiring devices intended for residential or commercial purposes. The NEMA standard does not define green as a color for wiring devices.
A receptacle with an orange triangle is an isolated ground device, where the grounding pin of the receptacle is connected to ground independently of the frame of the receptacle and wiring outlet box. The receptacle itself may be any color, but contrary to popular belief, a receptacle is no longer an isolated ground device because the receptacle itself is orange, although this was formerly the case in the United States.[14]
The orange outlets indicate that they are isolated ground, the ground circuit is not bonded to the mounting ears. They are specified for data processing equipment to keep from sharing the ground circuit with possible sources of electrical noise. Red outlets typically indicate that they're hooked to an emergency power source that will continue if the main power goes out. You usually see red outlets in hospital rooms and this is what things like respirators/ventilators will be plugged into.
IBM figured out in the early 80s that this isolated ground boondoggle was snake oil and they stopped including IG in the specs for their equipment. There are some self proclaimed "experts" who still cling to this fantasy but it is finally dying the death it deserves.
A lot of older equipment was susceptible to electrical line noise. Heck, the first personal computers I worked on back in the late 70's and early
80's would conk out due to the static electric charge from you touching the case after you walked on carpet. I'll use the isolated ground receptacles in commercial situations where there a lot of motors and refrigeration/AC compressors on the same power system.
IG will do nothing to stop an ESD hit through the case. The real "PCs were very noise tolerant and by the time IBM came out with the PS/2 they were using a multi layer board that didn't even need external shielding. I made several of them with wooden cases
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).
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.
Computers using the old linear power supplies were VERY sensitive to line noise - which made isolated ground power circuits almost a requirement in many applications.
Switch mode power supplies of today are extremely noise tollerant - but a very large majority of them are also extremely noizy - with little or no EMI filtering to stop the hash from the chopper circuit from radiating back into the power supply, along with the associated harmonics.
That was what I was told but we did do some rudimentary testing with a field strength meter and this was not noisy at all. It was certainly meet FCC class A spec.
What PC used a linear supply? The first PC-1 5150 used a switcher supply and every one after that did too, Virtually every linear supply I ever saw at IMB was ferro resonant and very noise tolerant.
They are all required to have a line filter to keep this out of the power cord. None of this has anything to do with IG. IG is intended to keep noise off the EGC
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.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.