GFCI Ground Fault Circuit Interrupter Inline C13 to C14?

| Here are my thoughts: | | Theoretically, one could argue that an individual grounding conductor from | each device back to the main bonding point would be the most reliable, since
| nothing that happens anywhere else could adversely affect any other device's | ground integrity. Obviously, this is impractical in terms of the number of | grounding conductors. You grouped things as appliances, raceways, etc, which | is a compromise, and I am not sure it accomplishes anything. It reduces the | number of conductors, but is still probably impractical. I am of course not | addressing systems such as hospital patient care with isolated grounds, etc.
The hospital case varies substantially, not only based on constant human contact to equipment, but also issues like perceived liability, as well as operational interference to very sensitive and life critical devices.
| Current industry design practice in the US is to properly bond every exposed | surface to a common egc system. Certain requirements, such as using pigtails | at receptacles and switches, prevent the most common possible interruptions | of that grounding system, but do not eliminate every possibility. Using | green wires instead of relying on conduit connections alone is a big | reliability improvement. I have not seen any studies or statistics proving | that our current industry practice is inadequate based on the number of | electric shocks/electrocutions on properly grounded systems. These accidents | more often appear to be the result of improper grounding.
I've been looking for an AC/MC cable that includes a conductor in continuous contact with the inside of the outer metallic armor, while also having a green insulated inner conductor. It seems all the cables with the contact conductor expect it to also be used as the grounding conductor. It seems all the cables with a green insulated conductor don't have an armor contact conductor. The reason I want both is to not depend on the armor as the grounding, but to have it well grounded anyway. This is for RF purposes so that the cables exhibit a consistent behaviour in radio fields.
| The "double framed" appliance concept is an interesting one, but certainly | not one that can be universally implemented. I am not sure it is necessary | if you prevent exposure to the live conductor to begin with. Remember that | typically a fault occurs within the appliance. We already have double | insulated appliances which accomplish the same thing except when they get | wet! In that case, the "double framed" would offer an advantage of a | grounded barrier to prevent a conductive water film on the outside.
I really don't see that many double frame or double insulated appliances. That is, unless they count paint as insulation, in which case there are a few more.
| Given a choice of using solid copper wire or a GFCI to protect a receptacle | or appliance, the solid copper is preferred over an electronic circuit. The | GFCI is acceptable practice where there is no copper ground (ie. older | two-wire systems), as it is better than no protection at all.
Agreed. But I'd still prefer separate conductors, one for the ground pins of the outlet strips (fed through the UPS if there is one in the cabinet), and one separate one for the rack cabinet frame itself. But having only one in common is better than none. And having two with both meeting at a subpanel in the computer room is better than having only one alone (IMHO).
| The bottom line is that I believe the current grounding practices are | adequate, when PROPERLY executed. I have seen older systems that were well | grounded because someone took the care to do it right. The biggest issue I | see is when poor workmanship or improper installation compromises the | grounding system. Even in industrial environments there are | "do-it-yourselfers" who don't have a clue. You won't eliminate this type of | problem by designing a "better" more expensive and complex system that won't | get done right anyhow.
One problem I have seen in more than a couple computer room installations that were grounded is that the rack ground wires were run separate from the power conductors. In some cases I found that instead of grounding them at the electrical panel (which was present) they were grounded by other means. In one case, grounded to a building beam by means of paint scraped off and using a clamp. In another, grounded to a water pipe (it was copper where atatched, but I could not verify if it was copper all the way, or commonly bonded with the electrical system very well). And in yet another, grounded to the A/C freon line. Luckily, I've not yet seen a case of grounding to a natural gas line. All these cases would definitely fail to come close to "adequate, when PROPERLY executed". Sadly, people thought they had grounded things, as they are often told to do that, but not how. And they wonder why they are getting such high error rates on ethernets, etc.
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snipped-for-privacy@ipal.net wrote:

IT people have no concept of proper grounding techniques. There is a common misconception that separate grounding electrodes should be used as the sole grounding means for sensitive equipment. I have seen it done, based on manufacturers instructions, in industrial PLC systems. Ground rods sticking up through the concrete right next to the panel. Not only does it violate code by not being bonded to the rest of the system, but as you point out it actually worsens the very problem they think they are solving.
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Benjamin D Miller, PE
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| snipped-for-privacy@ipal.net wrote: |> One problem I have seen in more than a couple computer room |> installations that were grounded is that the rack ground wires were |> run separate from the power conductors. In some cases I found that |> instead of grounding them at the electrical panel (which was present) |> they were grounded by other means. In one case, grounded to a |> building beam by means of paint scraped off and using a clamp. In |> another, grounded to a water pipe (it was copper where atatched, but |> I could not verify if it was copper all the way, or commonly bonded |> with the electrical system very well). And in yet another, grounded |> to the A/C freon line. Luckily, I've not yet seen a case of |> grounding to |> a natural gas line. All these cases would definitely fail to come |> close to "adequate, when PROPERLY executed". Sadly, people thought |> they had grounded things, as they are often told to do that, but not |> how. And they wonder why they are getting such high error rates on |> ethernets, etc. |> | | IT people have no concept of proper grounding techniques. There is a common | misconception that separate grounding electrodes should be used as the sole | grounding means for sensitive equipment. I have seen it done, based on | manufacturers instructions, in industrial PLC systems. Ground rods sticking | up through the concrete right next to the panel. Not only does it violate | code by not being bonded to the rest of the system, but as you point out it | actually worsens the very problem they think they are solving.
As an IT person I ... see this a lot. Not grounding at all is most common. Ground WRONG is 2nd most common. And this is before we even consider the issue of surge protection (worse).
One thing I have noticed is that radio and TV stations generally do a much better job of grounding. When you have grounding issues that effect the performance of equipment, you readily hear and see it with analog sound and video. With computers, there will be data failures, but it won't be obvious what the cause is. With radio and TV switching over to digital, there is a good chance that new or modified installations there will become increasingly poorly grounded (especially those with no engineering experience from the analog days).
I think one thing where people get confused is thinking that the ground wire on the electrical panel is somehow "dangerous".
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Will wrote:

You are probably having problems because of the asymmetrical loads from switching power supplies. For grins, try plugging in a noise filter between the GFCI and the power strip for the servers. Tripp-Lite Isobar strips have noise filters built in. http://www.tripplite.com/EN/products/product-series.cfm?txtSeriesIDt&CID=1
http://tinyurl.com/6pvh5q
[8~{} Uncle Monster
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Doesn't the power cord have a C14 on one end and a normal AC plug on the other end? Wouldn't it be easier to put the GFCI on the AC plug end?
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I think you are right. It would make more sense to have a GFCI at the base of the power cord, presenting 5-20R to the 5-15P or 5-20P plug of the power cord.
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The purpose of a GFIC is primarily to protect people not property. The way you describe your installation, the same result should be achievable if you can be certain that all conductive surfaces people can come in contact with are grounded.
Any leakage to ground can increase probability of trip. This leakage can arise from capacitance to ground, electrical leakage to pumped fluids, etc. The more devices in parallel, the greater the problem. I have had situations with pumps where leakage to the protective ground caused trips, probably from inductive kicks, when the pump was switched off.
Bill
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Believe it or not, Wal-Mart will sell power strips with GFCI plugs.
Just power each PC (or small cluster) with it's own power strip and you are home free.
The ones I have seen only have #16 wire so the continuous load should be kept around 10 amps although it's rated for 15 amps.
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| Believe it or not, Wal-Mart will sell power strips with GFCI plugs. | | Just power each PC (or small cluster) with it's own power strip and you are | home free. | | The ones I have seen only have #16 wire so the continuous load should be | kept around 10 amps although it's rated for 15 amps.
He seems to have a rack cabinet cluttering problem with just his cords (if they are getting in the way where closing a door could pinch one). Adding a power strip for each 10 amps worth of computers could make this worse.
It sounds like he needs a bunch of short cords. There are places that sell 1 foot long cords. These are good for rack cabinets with outlet strips that run vertical in the back on both sides.
And he needs to ground all the cabinets together solidly and connect them to a ground feed. Then if someone does cause damage to a cord, he can catch the culprit red-handed.
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