ground wire question

Dave Hi, thanks for your response, "isolate emi filters in PC power supplies". Is there any way to have this tested?

Thanks, DJ

Important to remember - PC is still powered even though it is turned off. The only fully powered off PC is one with the wall plug removed. Never remove or install anything inside a computer with power plug attached to wall receptacle.

Notice that power switch is push button. There must be electronics to monitor that switch. When electronics sees switch temporarily pressed, then 'monitoring' electronics orders the power supply to turn on. IOW there is always power in that power switch 'monitoring' electronics. Only way to completely remove power from motherboard, power supply control circuit, and some peripherals is to pull power cord from wall.

Remov> Phil

One indication of internal and intermittent wire problems is how severe is the dimming. Placing a heavy load at the end of that circuit may tend to aggravate the problem. With a heavy load, then voltage at end of that wire would be significantly lower (which means of course you have the necessary too - 3.5 digit multimeter).

Heavy load (ie electric heater) at end of circuit would also cause a noticeable dimming of incandescent lamps that share same circuit - if wire in wall is a problem. Dimming of lights means something is wrong or weakened.

Electrician could discover why problem exists. But more important is to first make the problem reproducible - so that you have something to show the electrician. Better you do the easy labor rather than have him do it at electrician rates. Take inventory of what is on, what is off, and what changes (on to off, or off to on) when dimming occurs.

Seriously consider having a new circuit run to that computer so that computer has a safety ground, as computer was designed to need. Safety ground (or GFCI) should also be in kitchen and bathrooms. Additionally, electrician could install the upgraded (required since 1990) earth ground and a 'whole house' protector. Minimally acceptable protector can be obtained at Home Depot for less than $50. Some electricians instead install an undersized Square D protector that costs much more money.

IOW give him enough that he can create and therefore f> "w_tom"

Line filters assume the safety ground (third prong) exists. If safety ground is missing, then sometimes run a finger lightly on metal chassis and feel the 60+ AC volts - a sort of tingle. This 'stray' voltage might cause your power supply control circuit (on motherboard) to lockout. But that would be unique to each computer design.

If leakage is caus> Dave

On Mon, 07 Jun 2004 04:26:09 GMT DJ wrote: | Phil | I have dial-up service, would my PC be at risk here also.

Probably no different than any other connection. Based on my experience, cable TV might have a bit more lightning risk.

On Mon, 07 Jun 2004 04:37:27 GMT DJ wrote: | Phil | I have heard people mention this, "power off" I have always shut down from | within Windows, START, TURN OFF COMPUTER, etc. How would I go about powering | off my PC?

There may be a switch on the back of your PC power supply. If not, there should be one on the power strip. Then unplug when not in use.

| Also, I don't have a reset button.

Some PCs integrate reset with the power button or a keyboard sequence.

The line filter is to keep power supply noise in, not to keep line noise out. It is part of the FCC certification.

You're busily chasing down a "PC problem" when the place you should be looking is in your sentence above.

Forget the PC for a moment. Fix the flickering problem, for

2 reasons: 1) It could kill you 2) It is likely causing the PC problem.

"w_tom" Hi, I've never had any problem with the lights dimming in this room. In the kitchen, the light over the table flickers occassionally, also sometimes when I use the microwave it will make the light over the sink flicker. I will have this outlet checked to make sure it is working correctly, then will let the newsgroup know if I still have problems. My PC doesn't shut down everyday, I never know when to expect it. So it may take a few days before it happens again. Is it possible to add a new circuit with a ground just in one room of the house? if there is a problem with this outlet? We have a new Home Depot close by, so I will check and see if they have the protector you mentioned. Thanks again, I appreciate the help. DJ

Yes, but ground is not your problem. PC's do not need ground to operate properly. PC's are grounded for safety. Consider a laptop - the line cord is two wires with no ground prong - it has no ground connection, yet performs all the same functions as a "regular" PC.

A surge protector won't address your problem, either.

Address the flickering problem first. If you still have a problem with the PC dropping power after the flickering problem is resolved post again.

I think I would take the computer to a friends house and find out if it is your computer or you house.

I have seen where a computer would not work only when plugged into a house where someone had cut off all safety ground wires in the breaker box. If computer comes with a safety ground wire, then computer is designed on the assumption that safety ground will exist. If that safety ground wire is not connected, then stray 60+ voltage might exist - which causes other problem and failures when computer is connected to peripherals.

Some computers have worked just fine without that safety ground. I have seen another fail due to no safety ground. We know (even from the HP Laserjet II experience) that missing safety grounds can cause hardware failure.

Will safety ground fix the problem? Maybe yes; maybe no. Just because a laptop designed only to work on two wires exists does not mean that a computer designed for three prongs will not fail on two prong power. Those two computers (the three prong verses two prong) are designed differently.

A surge protector is not to fix the problem. The surge protector recommendati> Yes, but ground is not your problem. PC's do not need ground to

There is a major difference between dimming verses flickering. This is why any response to your problem can be difficult. No light anywhere should flicker when the microwave is turned on. Was the light flickering or dimming?

You can have a dedicated circuit with ground > "w_tom"

Tom - for lord's sake - he's got flickering lights. In addition, his PC powers off. How on earth can a missing ground casue either one of those problems? Which problem presents greater risk to him?

Your presentation contains no facts, and invalid assumptions. Saying a "stray 60+ voltage might exist" is a non-specific, unsupported speculation. It does not state where the voltage is, why the figure is 60+, where it came from, and whether it is a "bad thing", a "good thing", or an interesting but irrelevant item. Aside from the power supply, the electronics is NOT designed with a three prong plug in mind. That third wire is there for safety. The NEC does not allow you to consider the grounding wires as a current carrying conductor (article 400-5 1999 NEC) - a manufacturer must not intentionally introduce any current to that grounding conductor.

Does he have flickering lights or just dimming lights? Until he answers the question that was posted previously, then do you really know?

In the meantime, 60 Hz AC leakage voltages can cause problems with the power supply controller on motherboard on some computers. I have seen it as previously posted. If you don't why it can happen, well then you were not a digital logic designer (IOW where does that leaking 60+ AC go?).

Instead of invoking the lord, look at the original post. He asked if missing safety ground can cause computer problems. The answer is yes. In addition to addressing the flickering light problem (which was already done and apparently does not occur when computer has problems), he also has a potential problem that is described as quoted:

Yes, a missing safety ground, in some cases, can also create this problem AND cause hardware damage. Will you focus blindly on the flickering lights and ignore all other potential reasons for that computer problem? The flickering lights possibility has already been addressed and is awaiting further information from the OP. No reason for you to now bring the Lord's Sakes into this discussion.

Yes that third wire is for safety. But some designs use it to carry away the 60 hz leakage. You have never seen an > w_tom wrote:

In about a dozen ways - but the main ones goes to the two main reasons the ground exists - short-path and drain.

a) And the effect of the latter becomes markedly significant when the neutral path degrades as opposed to the path opens. And, in the real world, ground and neutral path problems often involve TWO errors of path, not just one. And a problem ground system is rarely steady state, but rather it is unstable, varying due to current in the wire, current density in the connections, mechanical vibration, and even to the shape of the conducting wire and its mechanical and electrical enclosure properties. And finally, seeing 60 vac on a non-peak-detecting meter is not the same as what is in the ground line. b) First, the earth ground lead does NOT just sit there. Second, it does NOT only conduct when the neutral goes to hell.

Anyone who has ever done any work with chassis and earth grounds knows that the earth ground does a HELL of a lot more than wait for a break in the neutral, especially to the low voltages of computer components. Some non-computer specs allow 3 volts between a chassis ground and an earth ground, and the one we use in circuits allows 6 volts between the grounded neutral and the earth ground - try that on an op-amp-capacitor power supply outputting 5 volts on its chassis-earth grounds and see what shuts off.

A poor earth drain can, and does, back-bias amps (including those in the cheap "artificial C" power supplies of the past ten years) and shut down equipment. So the cheap supplies isolate from the earth ground and float the whole supply off neutral - works if the case isn't grounded.

c) And next, then why does a light flicker? Use a fluorescent and drop the voltage across the inputs to 60 volts back and forth a few times by raising the neutral voltage and see what flickers. Plug in an A bulb and drop the voltage to 60 volts for a couple cycles and it will flicker.

The modern op-amp-c computer supplies are so slow they can't even buffer a christmas light flasher spike - why does anyone think they can handle a loose neutral or spiking ground and not shut down the processor?

I snipped most of your rambling post, but the part I left represents the major problem I see with what you posted.

1) His PC is not connected to ground, so we can dismiss a spiking ground as the problem. 2) You kept dragging the neutral in. I never mentioned neutral. In addition, it seems you think that the grounding conductor will carry current when the neutral breaks - you said : >b) First, the earth ground lead does NOT just sit there. > Second, it does NOT only conduct when the neutral goes to hell.

The ground conductor is there to conduct fault current. In the absence of any other defects, the ground conductor will NOT conduct current when the neutral opens.

You mention a break on the neutral, fluorescents "seeing" 60 volts instead of 120 and so forth. I agree - a problem on the neutral can certainly cause the PC to drop power. But the issue is not a problem on the neutral - it is whether or not a missing equipment grounding conductor can cause a PC to drop power. It cannot. You need some other problem aside from a missing egc to cause a PC to drop power when it shouldn't. do with the neutral

He said flickering. Whether you wish to quibble on flickering vs dimming, he's got a symptom that could be a disaster in the making, and is a probable cause of his PC problem. It is the first thing to address.

Again, a non-specific reference to leakage voltages. Specify the leakage: where is it and what causes it? For example, lets say you have 60+ volts on the PC chassis with respect to ground, due to a leaky capacitor. The correct fix is to replace the capacitor. You need to specify what you are thinking of when you talk about "60 Hz leakage voltage"

You may have seen it, but you have not identified the source of the leakage, nor stated where the voltage existed. Where did you connect your meter leads? How did you determine it was "leakage" voltage and what do you mean by "leakage"? How did you determine it was 60 Hz?

If some component is leaking such that it creates a condition where 60+ volts (with respect to some point you have not yet identified) exists where it shouldn't, then isn't replacing the defective component the correct fix? (I mention 60+ volts, as that is the figure you used in a previous post. ) If the chassis of a PC is at 60+ volts (or some other objectionable voltage) with respect to ground due to a leaking capacitor, and that is causing the PC to drop power, installing an equipment grounding conductor very well might make the PC stop dropping power. You haven't resolved the problem, you've only hidden it. The correct thing to do is determine the source of the problem and fix whatever is causing it.

Because you are unable/unwilling to specify what you are talking about, you deremine that someone else is not a digital logic designer (or a piano tuner or a farmer or whatever)??? That makes no sense.

The answer is NO, with no equivocation. You need some condition other than a missing equipment grounding conductor, to cause a PC to drop power when it should not. The NEC prohibits using the egc as a current carrying conductor. Perhaps you don't understand the distinction, since it is NEC terminology. It means that manufacturer and designers cannot intentionally design or build a PC that requires the egc to carry current under normal conditions. It is for safety only.

Look, this should be simple. You claim that some PC's need the egc to avoid the symptom that the OP asked about - dropping power. You say designers use the egc to prevent that. What are the specifics you have in mind? How do the designers use the egc to accomplish this? What is the circuit?

A perception of rambling in a structured document implies a lack of understanding by the reader. So i am sorry you don't have any experience in basic grounding engineering and can't follow a simple engineering conversation on grounding - but since this NG is not a course in fundamental engineering, i would suggest you do as i did when first entering the field, and get a degree in EE, work in the field for a few years (I have over 30 years including groundings on several hundreds of miles of cables in each of several military devices, and I have a PE in NY, CA, MN, and several other states), and successfully fix a few problems using that knowledge and experience, and then perhaps you might understand a NG conversation that only touches on the basics of grounding. I will, however, point out some areas you might check for your further insight.

Rule 1 - grounds ain't what they seem -be they chassis, RF, earth, subset grounds, or drains. Rule 2 - make a schematic - of the grounds, with each wire, part, board, and frame a resistor and antenna, with the air a resistor. It will be incomplete, but it's a start. Rule 3 - Kirchoffs law and the conservation of energy does not stop because it is a ground.

No, you can't - remember that the weak part about theorists with little experience is their absolute beliefs - so we will start with the fundamentals-

Ask which ground? the several machine grounds or the circuit ground? 1. All machines have a reference ground, designated by the tree. The chassis grounds, designated by the antenna, normally spider to the earth reference point. 2. A good ground for one source may not carry ground for a second source firmly attached to the same ground strap. (Particuarly true in RF locations.) 3. Some power circuits do not have a direct ground. ( e.g., type 2)

1. If the two types are connected, there is direct path machine to earth. There is ALWAYS an indirect path form machine gorund to earth ground. Grab a frame of a floating power system with a lead and see if it sparks

-std practice for old grounding engineers - if it does, it is badly indirectly grounded and you then direct ground it - and go back and break up the new loop.

A).back to the existance of a direct connection of machine ground to earth ground - you do not know for certain the direct path does not exist. Are all appliances connected to the computer also isolated? or is one a grounded appliance that has a grounded cable shield and/or phone line lead (modem) that provides a path from the computer chassis case ground to the earth via the appliance (phone, monitor, etc) and its outlet ground?

B) The circuit ground and EFI/RFI -If the circuit neutral is loose "in the wall", or any connection is defective, the current flow is sporadically interrupted. That interruption creates the voltage spikes that are a major cource of EFI/RFI problems, with attendant induced high voltages in any nearby conductor - like those in the power supply, particualrly the slow agc loop of the artificial C op amp. .

Of course - it is the main connector to the machine for current or lack thereof; a path for induced high voltage EFI/RFI; it is the required bridge to the earth ground "after the box" - at the power panel at minimum; it is the storage area for the indirect ground drain when there is no direct ground link; and it is one antenna for any spiking energy induced from nearby sources.

If you mean ONLY then, then you are flat out totally dead wrong.

It always conducts current. I realize this is heresy for residential and commercial electricians, and in the context of it being a conductor of power current, the type a neutral sees, no, it does not conduct current. But any engineer that says it does not conduct current slept thru fields and circuits

101. The earth ground on the machine and in/on the power tray most certainly carries current. It is the primary drain of accumulated charge due to the ALWAYS present induced currents - open the earth and let the charge build up, and you WILL eventually spike a hole in a chip. If you use an indirect ground (e.g., a spike ) in lieu of a direct wire, you had better know what you are doing, and make sure the physical spike is properly sized and out of any other fields, and some tech doesn't take off the sharp thing on the appliance becasue it gave him an "owie". Made them, put back the ones others had installed, replaced them with directs, and fixed the damage.

power neutral, or machine neutral? Or a neutral that is assumed by some newbie design engineer to be a drain when it is not capable and then some poor chip sees the accumulated drain charge as a bias?

I've been at this too long and seen and solved too many problems with other designs to ever discount the basics: charge accumulates, charge flows, voltage varies, and a wire is not the only path to be put on the schematic.