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60 V .3 MA from PSU on all rails is this normal?

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July 12, 2006 8:27:49 PM

I can sometime feel a current from the metal parts of my case. I meassued this with a multimeter and found it to be about 60 V .3mA AC.

The measurements are with me holding one prong and touching any wire from the PSU, or any conductive part of my case.

I checked and you need 16mA-110ma passing through your chest to pose any risk. http://www.cdc.gov/niosh/elecovrv.html

I get the same results from any of the rails when the PSU is on, but the system is off.

I get the similar results for multiple PSU plugged into multiple outlets while not connected to a motherboard and without shorting the green pin to start the PSU.

So either this is normal or my appartnemt has a wiring problem.

I would appreciate it if someone with a multimeter handy would tell me if thier PSU outputs any AC current when the system is on or off?

Or is someone who knows more about housewiring than me can tell me know how to test to see if my outlets are wired properly with a multimeter.

More about : psu rails normal

July 12, 2006 9:12:06 PM

It soulds like you have a house wiring problem, Proably the earth ground. The earth ground is used to dispate stray current.

If you live in the US and have a 3 prong receptical. The 2 vertical slots are the main power, Line and netural, with the earth ground the round below them. You should measure 110-120vac across these (line netural). The Netural is the Longer Slot. If you measure from netural to the earth ground (round, below the slots) you should have 0 vac. Earth ground to Line should measure 110-120 vac. There are some cheap line tester that sell for $10-15 at your local hardware store. They have 3 lights which will give you the results and or problem.

Depending on the age of your house it was comon back in the 60's and 70's to try to use the metal box for ground, with out connecting it to the receptical. Then there were cases where painters would cut them off and not even connect them up. They also used and still do use the Quick connect connection. Never have liked these, over heat when exposed to high loads.

My dad's house (tree 10 ft from house) was struck with lightning bridging to his underground feeder to shop and to house plumbing. Blew out many breakers, connetions inside receptical boxes and Burned out the earth ground for his panel. With a scope connected across the earth and neutral it looked like a capacitor building up and dispating.

AC will take the path of least resistance, and want's to return to the source. Either your panel or line transformer.
July 12, 2006 9:14:43 PM

There's two answers to this question. If you live in the UK then in theory you should never get built up charge on the metal casing as it should be grounded though the wall outlet. If you do live in the UK and are still getting this, try testing a new power wire on the computer, or, if you are an expert in electricity, check the wiring.

If you don't live in the UK then you won't have a grounding feature in your wiring and although build up of charge can mean faulty equipment, it's something you often have to live with.

0.3mA isn't enough to kill you. High voltages can cause burns and high currents can disrupt the heart but you aren't in any danger from either. I once experienced this build up of charge on objects when I went to france. The lamp in the hotel room became live with a small current, when I was turning on the lamp and put my feet onto the concrete I jumped about 5 feet in the air.

The PSU in your computer is encased in metal and touches the metal of your case. All it takes is for one piece of the PSU to touch the PSU protection and you get the build up.

**EDIT, just seen your post that the US uses grounding.
Related resources
July 12, 2006 9:19:22 PM

The higher voltages in the UK are actually saver than the lower ones in the US. Voltage 220 and > are powerful enough to knock you clear. 115 here in the US just makes you hold on, and will not knock you loose.
July 12, 2006 9:34:45 PM

You didn't said how you take the measure. One probe to the case and the other? To the ground mains wire? To the PSU ground plane? To what?
July 12, 2006 9:36:33 PM

Do ALL of the testing on the WALL receptical.
July 12, 2006 11:13:24 PM

I held one probe while touching the other to my case to measuse the voltage and current I was recieving when touching the case.

Zero difference between that and simply touching the case, only this way I get a measurement.


I did the same with the power rails. Every line coming out of every PSU connected to any outlet has 60 v .3 mA AC.

I live in an apartment my outlets were all 2 prong but two were upgraded to 3 prong by someone who may not have know what they are doing.

Which maybe be why there is no difference between using a three prong outlet and 2 prong outlet via an adapter.

I just got a Black and Decker Home Wiring book from the library. By tomorrow I will know how to test and be able to correct any simple wiring errors.
July 12, 2006 11:45:02 PM

You held one probe in your hand, and touched the other probe to the case?

That will measure nothing.

Quote:
I did the same with the power rails. Every line coming out of every PSU connected to any outlet has 60 v .3 mA AC.



You're probably not measuring it correctly.

If the boxes behind the 3 prong outlets are metal boxes, then simply screwing them into the box will probably...probably... ground them sufficiently. It is not ideal and they should be physically tied to the metal box, but the screws will probably tie it to ground.

Now, lets talk about your house. For you to actually feel a voltage while touching the case, you yourself would need to be grounded [or touching some other potential]. It's sort of like a bird sitting on a power line. They are sitting on thousands of volts of electricity, but they aren't dead. Why? Because there is no current path. So, in order for you to feel the electricty, there has to be a path. Are you standing on a concrete floor in bare feet? On carpet? Wood? Are you sitting down? What kind of chair?
July 13, 2006 1:43:19 AM

Quote:
You didn't said how you take the measure. One probe to the case and the other? To the ground mains wire? To the PSU ground plane? To what?


I will make it simpler for you.

Set you Volt Meter to Volts AC range 0 - 200v

1. Unplug your computer from the wall.

2. Stick you probes in to the 2 Slots on the wall plug.
(slot to slot) Write your reading down.

3. Now move the Short slot Probe to the round hole.
(long to round) Write your reading down.

4. Now move the Long slot probe to the narrow slot.
(short to round) Write your reading down.

Post Results.
July 13, 2006 2:41:55 AM

Basically, here's what I got and what it should be. I used to have this problem all the time at my other house, come to find out it was because the outlets weren't grounded properly. At that time, I was seeing anywhere from 60vac to a full 115vac from the computer case to the common. Solution? The house ground was bad. The way the electrician fixed it was by joining the common (aka Neutral) and the household grounds to a water pipe.

Visit this website

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/hse...
July 13, 2006 2:53:49 AM

Grounding to pluming is no loger recomended. Mainly due to the use of pvc piping. My dad was grounded that way and a by ground rod, when lighting struck a tree near this house. Bridge over and burned holes in the copper pipe under the slab. Expensive repairs. Use ground rod only from your distribution box.
July 13, 2006 10:58:22 AM

It is code in my area that you must be connected to the cold water pipe and 2 ground rods. Most areas bring water into the house via copper, and the code specs to connect to that copper pipe within so many inches or feet [I forget the code] from where it enters the house. This is obviously because, as you said, you don’t know that all the copper in the house isn’t broken by pvc, so you have to go back to where it enters the house and attach the ground there.

As for testing at the outlet. You need to measure if the ground and neutral are tied together, i.e. you need to measure the resistance between ground and neutral. Measuring voltage between neutral and ground will not tell you if the ground lug is actually tied to ground....unless of course there is some voltage on it. If it's floating, you won't know it by measuring only voltage.

It is still possible that the earth ground at the panel is broken, even if the neutral and ground appear tied together at the outlet.
July 13, 2006 1:26:40 PM

Pain, I have given him detail instruction on what to measure. I do not know or think he know what all of the terminology is. The first time He was tring to measuring the computer.

I worked on power distrubition systems from 110 to 13.4 KV and helped another person that did 134 KV. 134KV will make your hair standup if you get near it on humid days. DID NOT LIKE IT AT ALL. Hated going in to the sub-station to roll feeders.

PS require a reference to ground, or they float. It's posiable that he has a PS in the process of failing. But Can not know that till the source is checked.

It is highly possiable that his line and neutral are swaped.

If he had a Newer APC UPS he would know this, because they check the source. A light will come on saying Check Wiring.
July 13, 2006 1:37:22 PM

I never said you didn't give detailed instructions.

I did say that code in my area requires ground tied to the cold water copper from the outside of the house. Basically for conversation, but whatever.
July 13, 2006 2:05:52 PM

I think the codes changed with in the last 2 code releases (6yrs). I took a course for the Journmans Liencen 5-6 years ago, passed 1st try. They were talking about the change then. They covered your area and all older house requiring 2 grounding rods. The code books are only update every 3 yrs. Most cities run 1 - 2 books behind. And add other requirment to the code. My house uses the under ground conduct that the main feeder comes in with. Have not found where or if it uses the plumbing. A lot of panels have a bridge tying the Netural and earth together. Based on weather it is a main or sub.

I'm not sure of Codesmiths intention. He did ask for help. Then proceded on his own direction. Must be a geologist, there trouble shooting skills are backwards.
July 13, 2006 2:31:40 PM

heh.

Yeah, I just replaced my panel and had to use 2 rods and a #4 copper to the cold water line, clamped above and below the pressure reducer. I have above ground service.

I have to add a subpanel in my house and replace the one in my garage too, and yeah, the main panel has the neutral and ground tied together, the subs have them seperated. That's so if you lose the neutral in the sub you don't have the possibility of current flow through the ground, but you know that. :wink:
July 13, 2006 4:49:07 PM

I have a friend that has a house that is so old it was wired with just 2 wire, no ground.

He had to replace all the breakers with GFCI, you known that was expensive.
July 14, 2006 6:19:14 AM

The 60VAC is caused by an ungrounded wall outlet connection and a pair of 5nF capacitors connected between each line and the case ground. Both capacitors conduct equally and therefore divide the 120V in half where they meet.
July 16, 2006 7:26:24 AM

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Stop and think for a moment. Anytime you can feel electricity, you are completing a path to ground and therefore you can use a multimeter to measure it with a multimeter by holding one prong and touching the other to the source.

(Assuming the current/voltage is withing the range of your multimeter and it lasts long enough)

60 volts of electricity is more than capable of flowing through a mans arm, down his body, through his shoes and carpet, through the carpet mat, wood flooring .....

---
Anway I know how to use a multimeter, and I know the basics of electricty from my physics classes,

So I understand volts, ohms, wattage, ohms law, flux, electromagentic fields ...

We never covered capacitance, impedence and AC current, nor did I know anything about how houses were wired until I got a book from the library.

Which is why five years ago I had my friend who has a 2 year Electronics degree put in some three prong outlets near my computer.

He knows that the bare wire is usually the grounding wire, but neither of us can remeber if he tested the outlet to see if it was properly grounded.
----
I read half the Black and Decker book and have tested all my outlets with a multimeter.

The three prong outlets that a friend put in near my PC have hot to ground 75v, neutral to ground is 44v.

It may not be connected to anything, or maybe they used repurposed the grounding wire for the doorbell or thermostat?

The only outlets in the appartment that are grounded properly are the GFCI ones in the kitchen that were recently upgraded due to a change in building codes.

With the other ungrounded outlets I get 40-60v hot to the center screw and 0-5v neutral to center screw.
---
I used an 3 to 2 prong adapter so nothing connects to the grounding wire as a temporary fix.

When I finish reading the home wiring book I will cut the power and take a look.

My guess is what I will find is what should be the grounding wire is connected properly, but its not actually grounded to anything.
---

I also know nothing about how powersupplies actually work other than what they due, convert 120 V AC to various DC voltages and keep those voltages steady depsite a constantly varing load.

So I am not sure what is ment my a Power Supply "floating".

Does that mean I should expect to see a small, but measurable current leaking to ground when connected to an ungrounded recepticle, or does that indicate that my PSU is somehow defective.

Sometime this week I am going to take a bunch of PSUs into the kitches, connect them to the properly grounded outlest via a 2 prong adapter then measure the voltage between the casing of the PSU and the grounding pin of the outlet.

If they all leak a small amount of current to ground then I will assume that is its normal for a PSU to do so if ungrounded.

---
July 16, 2006 9:21:13 AM

Hey Pain, I totally agree mate. There is no reference for a true voltage to be measured..
Current is measured in series with the device and voltage is measured across (parallel) the device.
Holding one probe gives no true reference point.
July 16, 2006 12:20:12 PM

Quote:
----
Stop and think for a moment. Anytime you can feel electricity, you are completing a path to ground and therefore you can use a multimeter to measure it with a multimeter by holding one prong and touching the other to the source.

(Assuming the current/voltage is withing the range of your multimeter and it lasts long enough)

60 volts of electricity is more than capable of flowing through a mans arm, down his body, through his shoes and carpet, through the carpet mat, wood flooring .....



That's what I said about a current path, but I don't think you're getting any usable reading by holding a probe in one hand and touching the other to the case.

If you want to know how much voltage is on the case [or anything else for that matter] then measure directly from a known ground connection, to the case. I've done enough electrical/electronic work in my life to know that 60V isn't enough to pass through all that stuff and give a valid reading, or give a shock. If you were standing on a concrete floor in bare feet, yes. On carpet over wood with shoes on, no...unless everything is soaking wet. :wink:

With that said, I'd check it out immediately or get an electrician to do it. Often, if there is a float [or open circuit] you'll get various readings with a digitial multimeter. It doesn't necessarily mean you are reading all those various readings you say, but in any case, you need to have it checked ASAP just to be exactly sure what is happening.
July 16, 2006 1:33:32 PM

Damn good advice. ALWAYS better to be safe than ... 8O
July 16, 2006 7:17:23 PM

Sorry I didn't mean to imply I was getting an accurate measurement of what the PSU was actually leaking to ground.

I ment that my method is giving me an accurate measurement of the voltage and current actually passing through my body I when touched grounded metal on my case on my case. (grounded in the sense that it is connected to the ungrounded grounding wire)

It was constant, but very weak and didn't feel strong enough to be dangersous, but I wanted to measure it, not guess.

---
I have been wondering why I get shocked sometimes and not others. Now I think I found the answer. For example I don't think I was shocked once all winter.

I seem to only get shocked or have measurable current on days when it is extreemly humid.

Thursday and Friday it was extremely humid and I could feel and measure current from four different PSU's that were plugged in to a 2 prong outlets, but otherwise "off". (I wasn't shorting the green grounding wire). I also could get a shock from one monitor's signal cable, but no the other.

The results varied from .2 mA to .4 mA but managed to convince me that there was nothing wrong with my PSU other than it being connected to an ungrounded outlet.

Today I can neither feel nor measure anything. I even took the PSU's into the kitchen and took measurements using the ground from a properly grounded outlet. Whatever current there is its below the .1mA my meter can reliably measure.
---
I asked my appartment manger about getting the outlets near my PC properly grounded, but its not going to happen.

I can't even convince them to enlarge the slot on the outgoing mailbox so that my netfix envelopes will fit.

If I want properly grounded outlets I will have to move to an apparment complex with modern wiring.
July 16, 2006 7:40:40 PM

The only way to get protection with a 2 wire (No earth ground) is with a GFCI. If you have access to the breaker for that circuit, you could take a look. The ground may have just been clipped and not connected. It was common pratice 30 yrs ago.

If they used metal conduct, as in commercial buildings, the conduit can be used for earth ground.

Without a earth ground a UPS unit will not work correctly. Has no path to ground. What a bummer.

Some old UPS units that were not switchers generated their own ground. Don't see these units any more.
July 16, 2006 7:52:24 PM

Quote:
Sorry I didn't mean to imply I was getting an accurate measurement of what the PSU was actually leaking to ground.

I ment that my method is giving me an accurate measurement of the voltage and current actually passing through my body I when touched grounded metal on my case on my case. (grounded in the sense that it is connected to the ungrounded grounding wire)



If you want an acurate measurment of the voltage on the case, measure to the case from ground. Your method isn't measuring anything.
July 16, 2006 8:05:02 PM

If is digital VM doesn't have a high impedence meter it want me accurate anyway. For measureing floating currents you need 200+ Meg-ohm min and a pico amp meter.
July 16, 2006 8:59:26 PM

Yeah. And, we could get scientific about how to measure to get various readings, and have discussions on what is actually being measured by holding the probe in one hand and touching the case with the other, but the bottom line in my opinion is that there is nothing of any value at all being measured that way. :lol: 

Now, if you want to have some fun, shove a ground rod up your butt, and put your tounge on the power outlet, and have someone measure the voltage on your body at various possitions between your butt and your tounge. :D  8O
July 16, 2006 9:49:31 PM

Yea, there is all kinds of stuff that can be done, But I can't be shocked any more because it may blow out my Neuro-Spinal Stimulator used to help control pain. But you can experience the feeling while walking through a sub station during a thunder storm holding a condutive flag pole.

The facts are he has a 2 wire (line, netural) no earth ground to bleed off stray currents. The impact to his computer may be mixed. Static can knockout componets. He may be able to use a 2 to 3 adapter, connecting the ground to the plate screw. Which will only work if the building has used metal boxes and conduct with no breaks to the panel.

Pain you and I both have more knowledge than the average person when when it comes to electrical systems. But our knowledge will have no impact on his apt wiring. Now if he is having problems with ouput voltages knocking out componets we may be able to suggest a fix.
July 16, 2006 10:44:50 PM

No, holding one end while touching the case with the measures the current/voltage from one lead to the other, which is the same as the current/voltage travelling into my body when I touch the case.

I have no idea what you are talking about when you say it measures nothing.

Do you mean

1) No electricty actually flows into the human body when it comes in contact with a 40-60 Volt AC power source and so there is nothing to measure?

2) That they my multimeter can't be sensitive enough to measure a constant AC current strong enough to be felt by a human? (My multimeter meassures AC current at .01mA resolutoin with +/- 1.2% accuracy)

3) When a human body completes part of a circuit the laws of physics no longer apply so that the electricity travelling through the multimeter magically doesn't have to equal to the electricity travelling into my body.
July 17, 2006 12:01:00 AM

Are you measuring voltage, or current? You can't do both at the same time with a typical multi-meter.

What I am saying is that you probably aren't measuring correctly.

If you want to measure voltage, then your will measure from ground to the case.

If you want to measure current, then you will put the meter in series, but like I said already, if you are standing on carpet over a wood floor, wearing shoes, then you aren't going to have a path for current unless it's a huge voltage.

With all due respect, you sound like you don't know much about electricity/electronics. It's OK that you don't and I mean no offense, but you aren't measuring anything that means anything with the way you have described you're taking the measurements.

With all that said. If you have a house that uses BX type cable [or conduit] meaning that there is a ground connected to a metal box, then it is possible the metal box is grounded. Have an electrician look at it to determine if you can sucessfully add grounded outlets without rewiring the house.
July 17, 2006 12:06:58 AM

Point 1 says (and to a degree, is correct in this instance).
No current is flowing through the body from the meter because there is no circuit made, unless you consider the continuation through your socks, shoes, carpet etc back to ground a complete circuit???

Point 2 is totally irrelavent and is nothing to do with the points you are trying to make (nor anyone else for that matter)...

Point 3 EXACTLY "When a human body completes part of a circuit". you are not completing a circuit, you are just a loose, floating, unconnected extension of the meter probe...

To measure current, the circuit is broken and the Ammeter is inserted to reinstate the circuit.

To measure voltage of something in a circuit (to tell you how much voltage is being applied to it), you simply need to connect your voltmeter (or in your case, multimeter) across it's terminals (one to each, lol, sorry).
July 17, 2006 12:19:22 AM

To expand on what Steve said. Lets assume you are measuring voltage.

You want to measure voltage from a known potential [ground, usually] to an unknown potential that you actually want to measure. If it's the computer case, measure voltage from a known ground to the case.

If you don't know what potential on the case, then measuring to your body by holding one probe and touching the case with the other isn't going to tell you any meaningful information. Why? Because you don't know what your bodys potential is. And, with you standing on a stack of insulators (wood, carpet, socks, shoes, dead foot skin cells) your body is basically floating electrically. The voltage reading you are getting is more than likely caused by EMF in the house, not by any real reading you might think you are getting.

If you want to measure current, then now your body is a big resistor, and you might be able to see some kind of current through your body, but from what voltage, i.e. what potential? And, what is that voltage? To get the voltage reading you need to measure it properly.
July 17, 2006 2:06:59 AM

I 100% agree that what I did tells me little about how the actual voltage and current being leaked to ground. (I do believe the results obtained can be assumed to put a floor on the possible range of the cases actual potential)

I thought that as long as I was the only path to ground available the voltage reading via the multimeter would be reasonably accurate as well, but I was wrong about that.


I plugged a PSU into a grounded outlet in the kitchen, shorted the green wire and measured red to black and got 5.25v. Then I measured the voltage from the red wire to myeslf and got 2.3 to 3.7 depending on how and where I stood. Repeated readings were consisitent as long as I kept my feet in exactly the same spot.

Somehow I am splitting the voltage with another high resistance pathway to ground? I am not sure :( 


But I do remain convinced that my multimeter readings are an accurate measure of the electricity currently passing into my body when I am feeling a shock from my case.
July 17, 2006 2:32:34 AM

If I recall each limb of the human body is estimated at 250 ohms each + 250 for the body. So your measurement is going throung a 750 ohm resistor. But since the reading is AC, the impedense drop calculation is a little different. GFCI trip at 30ma delta between netural and line. With 115vac 30 ma is enough to kill you in the right condition. A gfci will trip before the duration is long enough to kill you.

Since you have felt a shock through you case, I would test the cover plate screw to see if a ground is present. If so use an adapter and connect to it. If not I would find another outlet to use.
July 17, 2006 11:26:35 AM

Quote:

But I do remain convinced that my multimeter readings are an accurate measure of the electricity currently passing into my body when I am feeling a shock from my case.


You've not actually confirmed if you are measuring voltage or current. If you are measuring voltage, then you are wrong because you aren't making the measurement correctly. To measure voltage you must go from a known potential [ground] to the case. One could argue that if your body is in good contact with ground then you may get a valid voltage reading from your hand [ground] to the computer case. I would argue that you aren't in good contact with ground...see below.

If you are measuring current, then I would be totally amazed that you are able to get a reading under the circumstances you've described, standing on a carpeted wood floor, while wearing shoes. IMO there wouldn't be enough voltage to overcome all those insulators, and if there were you wouldn't want to be touching it or be capable of breathing after you did.

Because of those 2 things, I don't think the results you are getting have any meaningful information, but it's really a moot point. You need to check the wiring yourself or have it check by an electrician.
July 17, 2006 1:07:42 PM

Ok man, I have been an electrician for a very long time now. First throw your multimete down, got to Home Depot & buy yourself a plug-in tester for $6 with 3 lights(preferably the one that you can test GFCI's with too). This will help you in several ways: 1) tell you if you have an open ground
2) tell you if you have an open nuetral 3) tell if you have the hot & the nuertral reversed....or any combination of the above.

My gut is telln me you have an ungrounded system & if you live in apartment, might be tough to fix if you arent an electrician. DO you know if you residence is in conduit, romex, or bx.

If you want, pm me & i can walk ya through some things.

I have seen alot of crazy things in houses over the years when people do their own electrical work over the years.
July 19, 2006 12:55:47 AM

I cut the power and took a look and the outlets are wired correctly, I turned on the power and carefully tested the copper grounding wire and it isn't grounded.

I think until I move to another appartment I will just not touch any bare metal on my case when the humidity is above 85%.

I will buy one of those testers and bring it when I check out appartments.

I wanted more room for storage and a backyard where I can grill, this just give me an excuse to start looking.
July 19, 2006 2:19:38 AM

If you got access to the panel, pull the cover off and take a peak. There should be 2 grounding bars, 1 for earth (bare or grn) and 1 for neutrial (white). There should be a #4 or #6 (green) gage wire running to the earth. Or a tye bar.

Or take a picture of the panel and bars and send them to me. And I will give you my 2 cents.
July 19, 2006 9:24:14 AM

I carefully read everything people suggested as to why my numbers would be meaningless, and used them as the basis for further reading about electronics and the effects of electricity on the human body.

If you are curious about it here is the best link I have found so far on how electricty flows through people.

http://www.allaboutcircuits.com/vol_1/chpt_3/4.html

--
I also discusses your points for some time with a friend who has a two year Electrical Technition degree from DeVery and 2 years of experience troubleshooting $10,000 AC boards for lucent mostly with a rather expensive multimeter.
---

The fact is I have several websites that say if I can feel the current its at least .3mA AC.

I have a $50 crasftman multimeter that claims to measure AC current with resolution of .01mA and an accruacy of +/-1.2% in the 0 to 20mA range.

I took each multiple measurements and got consistent results, when I raised one foot off the ground and got a different set of consistent results.

I also know how my multimeter behaves when something is either out of range or is fluctuation to erratically to measure.

I even tried measuring the potential between the hot of a 120v outlet to a metal sheet on I placed my rug. Trust me rugs can conduct electricty better than you would expect. I didn't test the amperage because I didn't want to endanger myself or the rug.

Point is until I come across some relevant principle governing the flow of electricty or the operation of multimeters that someone has yet to mention I am going to trust my multimeter.

--
I was interested in discussing the reliablity of my measurements because I like to learn things. I almost chose Electrical Engineering over the philosophy/computer science degrees I picked up.

However since its gotten to the point were some are repeating previous remarks without elaboration and others are thinking about foriegn objects in my backside, I think I am at the wrong forum to get the answers I want.


Several of the electronics site I have visited have forums and the people there are probably used to carefully explaining things such things in sufficent detail to satisfly me.
---

PS I am still interested in my original problem. That being ground wires in my outlets are connected correctly, but not actually grounded to anything, and my PSU is leaking a perceptiable amout of current to ground, as does another PSU and one of my two CRTs, but not enough to be painfull and apparently only on days with extreemly high humidity.


Unfortunately since none of the outlet center screws are grounded (except the two properly grounded GFCI outlets near the kitchen sink) I am not optomistic about there being a solution that won't involve me either knocking holes in wall to check connections or opening up the main breaker box, which I wouldn't be comfortable doing in a rented appartment.[/u]
July 19, 2006 11:00:24 AM

Look. With all due respect. you go right ahead and believe what you want to believe. I asked for clarification on several points in how your were doing the measurements and told you how to properly measure the voltage on the case, and all I get back is that you've talked to 'someone' with 'some experience' and therefore you must be
right. OK, then you're right.

There are certainly situations where one might want to use unconventional procedures to make certain measurements, and there are certainly times where reality defies conventional wisdom, but I would still recommend starting with conventional procedures to make the measurements before jumping to the unconventional. If you want to know how much voltage is on the case, then make the measurement correctly. I would also recommend starting with understanding how the outlets are wired and if they can be easily grounded, and not how much stray current you have between the computer case and a houseplant. :wink:


Quote:
However since its gotten to the point were some are repeating previous remarks without elaboration and others are thinking about foriegn objects in my backside, I think I am at the wrong forum to get the answers I want.




Um, that was a joke and I wasn't even talking to you. But, if want to learn, then think about what I said. Your body is a big resistor and if you have a potential from your butt to your head, then you could measure different voltage at different points of your body.

I will be happy to go into more detail, but I will not do it if you won't respond to questions and give details when asked. That's why we're repeating information to you because you aren't responding to questions except to say you must be right. You also must understand that if you have a power problem, your best advise is to call an electrician because you may have serious, potentially dangerous problems that need to be resolved by someone who can look at your situation in person, and not try to decipher the problem from an internet forum.

I'm glad you have a friend with a degree and experience. I have a degree and experience too, more than him. Woot for me.
July 19, 2006 11:32:37 AM

Quote:

I'm glad you have a friend with a degree and experience. I have a degree and experience too, more than him. Woot for me.




:lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol:  :lol: 
July 19, 2006 11:34:59 AM

Having said that, I probably do too although I don't practice it anymore lol
3yr City and Guilds T224 Electronic Servicing. Sorry, I can't translate that into an American equivalent. :lol:  :lol: 
July 19, 2006 2:50:47 PM

Sorry, I did in fact assume that you were making a joke.

There is too many topic going on here.

We got my grounding wire that isn't very well grounded. We got ungrounded PSU leaking current when the humidity skyrockets.

And finally we got more than one person giving reasons why some numbers that really don't have a lot to do with the other two issues may me meaningless.


As far as improving my understanding of electronics....

My point is that we are obviously thinking about things in different ways and we don't seem to be getting any closer to identifing in what percise way our understandings differ.

Rereading my physics textbook, playing with a 300 in one project kit and visiting a few websites doesn't make me think I am an expert. I learn quickly but not that quickly.

My friend is intelligent, smart enough even to realize what he didn't learn earning his 2 year degree at Devry is a lot more what he did learn.

We even discussed the posiblity that he is misundertanding something and passed that missunderstanding on to me when he explained some things I was having trouble with.

Right now I would say I am about 60% certain I am right.

Mainly because I had been waiting weeks for my case to start shocking me again so I can run tests and when I could just barely feel a current the reading I got was .3mA. I just now discovered that the limit at which a human can detect an AC current at 60hz is .3-.4mA. When I make the measurement I had no clue what to expect, so if my method is flawed its quite a coincidence.

Anyway as far as my interest in understanding electronics better goes the conclusions are less important that the reasoning.

Even if I knew I was wrong it wouldn't help me unless I could find out exactly what I was misunderstanding.

Even if are 100% correct in your understanding it doesn't mean you can quickly and correctly identify the percise source of my misunderstanding then come up with a way of explaining it that I will understand.

We could probably have it sorted out in less than 30 minutes of real life interaction with a chalk board.

Anyway posting on an electronics forum has yeilded a lot of links to reference matterial that is few steps beyond my level of comprehension. I am going to have to hit the books to even fully understand the following.

Quote:
A leakage current tester measures leakage while simulating the impedance of a human body, generally about 1,500 W in parallel with 0.15 µF


Reading just a few pages has revealed more than a few gaps in my knowlege that I will to fill before I can move on.
July 19, 2006 3:32:51 PM

Quote:
Even if are 100% correct in your understanding it doesn't mean you can quickly and correctly identify the percise source of my misunderstanding then come up with a way of explaining it that I will understand.

We could probably have it sorted out in less than 30 minutes of real life interaction with a chalk board.



Precisely.

I think all this talk about current and voltage is all beside the point and really does little good to help you solve the problem of having poor grounds in your appartment.

Get an electrician to look at it, or at the very least put a GFI outlet in the outlets you use often, and that will prevent you from killing yourself until you can move to another appartment.
July 20, 2006 3:29:59 AM

There is nothing to add to this :
Quote:
I think all this talk about current and voltage is all beside the point and really does little good to help you solve the problem of having poor grounds in your appartment.


But any jolt you can feel is enough to kill if the condition and time (duration) is correct. Alway play it safe, the other option is not good.

If I can help in any way just contact me.
July 20, 2006 3:33:14 PM

GFCI's will only work if hooked up to a properly grounded system. The new GFCI's out will not even work if they are hooked to an ungrounded system per the new UL requirements.

GFI's sense a varience from hot to ground ( varience of .006ma..if I remeber correctly ). One of the reason why you shouldn't hook up refrigerator up to a GFI, you will get nuisance tripping.

Just wanted to clear that up.
July 20, 2006 4:12:39 PM

His only option would be a GFCI Breaker.

They are expensive, around $50, but it's cheeper than a 911 call.
July 20, 2006 4:22:55 PM

Again, the GFI breaker will not do any good on a circuit that isn't grounded sufficently.

I do side work...lol....where does he live?
July 20, 2006 4:29:37 PM

I thought they sensed the difference between hot to neutral, not hot to ground. If you don't have as much current in the neutal as you have in the hot, then you have a leak to ground [outside of the outlet] and the breaker trips. I thought that was the whole point of a GFI.

The point is taken that you still want to have a properly grounded system. I'm going to test it by dropping the ground off a GFI and see if it trips the breaker, because what you say is one of those things that defies logic....but doesn't mean it's not true. :D  I guess they might have done that to make you absolutely have to have a grounded outlet, else the gfi will trip and you won't have power. Too bad some people might then just say screw it and remove the GFI. Sort of defeats the purpose of the GFI, IMO.
July 20, 2006 4:40:36 PM

He has the ground bars in the breaker box. And he has a 3 prong recpt GFCI in the kitchen. So it's proable in the breaker box. Like you said he has the GFCI requires a earth ground to work. The kitchen works.

Pain you are right with the montering of the current between the line and netural. I belive the threshold is 18-25 ma delta, but I may be wrong on the values. But they use a earth ground to trip the gfci. Once the gfci is wired corectly then only the line and netual is needed. Which is what I think you were tring to say.
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