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Electric current coming in PC and other electronic devices.

Last response: in Components
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May 10, 2011 8:01:05 AM

Hi
For 2 days(after the rain),I am noticing that electric current is flowing throughout the cabinet of pc(sometimes) and also in my xbox 360 console(always) :( 
I felt a shock when i was trying to connect my console with my monitor.Even the current is flowing through the vga cable of the monitor.The whole setup is connected to a ups and then the power strip extension board.

Its wierd to have such problem as that may damage my devices.
So is there any device i can use to avoid this.Such as a belkin surge protector or so?

Please guide
a b ) Power supply
May 10, 2011 1:19:35 PM

(1) Adding a Surge protector will not help. Your UPS should have one built in.

(2) The problem is with your earth ground. Explaination (Using US wiring).
3 wires. One Hot 120 VAC, One nuetral Tied to Earth ground at some point before it gets to house. and the 3rd wire (round prong) is tied to earth ground at the House. This 3rd wire (ground) should be attached to the Case of of all electrical units that have a 3 wire power cord. Quick reason - Prior to this it was possible to revearse the Hot so that one case ie Refidge was tied to nuetral and a 2nd unit, say toaster was tied to the Hot - Wfe would get hit with 120 VAC if touch the case of both, or in tis case if barefoot she touched the toaster - Lost a few good ladies. So way back the earth ground was required Now if the Hot got reveased, you just blew a fuse.

Now to your problem - You have a poor-to-no earth ground. As I mentioned the earth ground goes to the "earth" at the home. It may tie to water pipes (metal) or a stake in the ground. Sometimes this provides a poor ground. Florida is a problem area in general, the ground has a high sand content. There are cases where a lighting has melted the sand round.

A second problem is defective wireing, ie the earth ground is open, or even worst the ground wire and the nuetral wire have been revearsed.

Bottom line, Get one of thoughs cheap AC testers (newegg has a good one for about $15) and test your outlets. You can also do it with a digital voltmeter (also about $15 at walmart).
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May 10, 2011 5:01:46 PM

But It has been a few months since the electrician did the electric earthing at my home by making a deep hole in ground,inserting pipes and a thick wire etc.Is that likely to be causing some fault.
Also a very less to no current comes in PC bit in my xbox 360,I can feel a great shock upon touching its metallic part.Is that because the PC pwersupply has over current and over voltage protection.
I am using PC and xbox console at same plug outlet.
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a b ) Power supply
May 10, 2011 5:14:31 PM

Do both the PC and the Xbox console use a 3 prong power cord.
If you have a large potetial differnce between the case there is a possiblity that on case hase the Hot tied to it and the other ground.

And NO, Overcurrent and overvoltage protection should have no effect.
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May 10, 2011 6:09:39 PM

The xbox power cord plug has 3 connections but i think the ground is not connected anywhere because the power cord at connector side has 2 outputs and also the supply has input for just 2 connections(as shown in pic). So no grounding at all after ac to dc conversion.May be that's the reason.
here is the pic



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a b ) Power supply
May 10, 2011 6:38:23 PM

Not US, so not sure how it is wired. But does sound like the Hot and nuetral wires (two wire AC) are switch at som point.

In US, On two wire AC a polorized plug is used to prevent plugging in the wrong way. Most electronics on two wire system will work plugged in either way, just that the case is Hot if the wrong way.
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a b ) Power supply
May 10, 2011 8:22:55 PM

darksmart said:
The xbox power cord plug has 3 connections but i think the ground is not connected anywhere because the power cord at connector side has 2 outputs and also the supply has input for just 2 connections(as shown in pic).

All electronics have a line filter. If the filter does not have a safety ground (not earth ground) connection, then the chassis will float to an intermediate voltage. If the Xbox has a three prong AC power cord, then everything back to the power board must connect all three wires to that board. Otherwise you have a floating ground. And an important human safety function has been compromised.

Does not matter what the electrician did to earth ground. With or without an earth ground, the same shocks would exist. And with or without an earth ground and with a proper three wire receptacle connection, then no shocks would exist.

Finally, how did you connect a three wire Xbox to a two wire power source? That should not be possible?
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a b ) Power supply
May 10, 2011 11:07:03 PM

^ Not US lok at the ground lug, not round and Hot/Neutral are much thicker than US. If you look @ his photo the Female end does not have the third ground lug and the Power supply only has Two metal prongs, not three. This is acceptable in some overseas locations providing that neutral goes where nuetral is suppose to go and Hot goes where Hot is suppose to go. The filter you mentioned is normally a EMI filter that prevents Radio freq from being inputed into device and also prevent the device from putting Radio freq back out on the line and not all electronics has this. In the states it is only required if the device fails FCC testing.
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a b ) Power supply
May 11, 2011 2:19:03 AM

RetiredChief said:
If you look @ his photo the Female end does not have the third ground lug and the Power supply only has Two metal prongs, not three.

That is a UK plug. It has safety ground. EU requirements also need that line filter - more than US requirements. Safety ground is necessary. Missing safety ground explains the 'hot' chassis.

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a b ) Power supply
May 11, 2011 3:09:41 AM

(1) Will agree, it looks like a UK plug. I have see that same plug elsewhere, just don't remember where.
(2) Missing earth ground "MAY" explain hot hot chassie. However for the chassie to be hot one of two conditions MUST be met:
.. (A) Hot is tied to chassie, would have blown fuse if Earth ground was present. But in this case it is not.
.. (B) Hot is connected to chassie, by a compontent, ie Resistor, or capacitor. The Value of R, or XsubC would have to be large enough to not blow the fuse if ground was connected, and This would cause current to flow to earth ground should it be connected and would trip a ground fault circuit breaker. You could be correct in that if an EMI filter is used it is posible for a capacitor from Hot to Chassie is there - Without the ground the chassie would be Hot (US=120, But UK thats 220/240). If you touched it initially the voltage would be max, however if you held on it would drop based on the ratio of Body resistance to XsubC.

What also seems odd is selling a powersupply with only two connections to the AC, unless it was safe to use in that configuration. This Power supply may be defective.

Laptop chargers (really just a power supply) often only have two wire AC cords - NO ground. The use a polarized plug to insure Hot is on the correct line. It would be possible for the Hot to short to one of the Output lines - But normally that will just "blow" up what ever the Powersupply plugs into
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a b ) Power supply
May 11, 2011 3:14:31 AM

RetiredChief said:
What also seems odd is selling a powersupply with only two connections to the AC, unless it was safe to use in that configuration.
Your's is the major question. OP should explain why he is using a two prong power supply. Makes no sense to me.


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May 11, 2011 4:27:58 AM

westom said:
Your's is the major question. OP should explain why he is using a two prong power supply. Makes no sense to me.

Actually thats the standard power supply by Microsoft,specially for the model of my console..It is of around 215W i think.
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Best solution

a b ) Power supply
May 11, 2011 1:05:19 PM

What I would do and what you would do depends on your knowledge and comfort zone.
You need to first determine if the problem is a hard short (Hot tied to case or (2) a soft short, tied to the case thru a resistor or a capacitor.
(A) a hard short Can be lethal and the problem isolated and MUST corrected.
(B) a "Soft" short can be corrected by tieing a wire to the case and the other end to earth ground.

Without a voltmeter, or an AC tester. You can use a lamp (Old fashion filiment type). with unit unpluged. Take lamp cord and tie a wire to one of the two prongs, the other end to the case. With the other prong tie a wire between this and either ground or neutral. Plug unit in - IF light lites up (bright) you have a Hard Short if ligtes up dim you have a low resistance. In both cases you MUST correct. If the light is dim, you have a low resistance tobetween hot and case If light stays off you have a soft short and can simply tie the case to earth ground by adding a wire between case and ground.

Alternative - Get a digital voltmeter (generally cheap <15 pounds and can be found at most auto parts stores. Our Walmart has one for $13). They are very simple to use and can be invaluble arount the home and autos.

How to use:
http://www.youtube.com/watch?v=UsDdQaIO7FI&safety_mode=...
http://www.youtube.com/watch?v=Ftc3EQGZowk&safety_mode=...
http://www.wikihow.com/Use-a-Multimeter
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May 11, 2011 2:55:39 PM

Just checked with AC tester.In my home,current is coming in both the terminals..the tester led glows very bright in one terminal and somewhat low in other.But when i connect the xbox console and touch the tester to its metallic part,the tester led glows in between the low and high in previous case.
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a b ) Power supply
May 11, 2011 3:15:16 PM

darksmart said:
Just checked with AC tester.In my home,current is coming in both the terminals..the tester led glows very bright in one terminal and somewhat low in other.

Voltage does not exist only from one wire. Your tester connects between what and what? A tester only touching one wire would not glow. To have electricity, both an incoming current path and an outgoing current path must exist. Both must be defined for glowing to say anything useful.
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May 11, 2011 5:11:31 PM

westom said:
Voltage does not exist only from one wire. Your tester connects between what and what? A tester only touching one wire would not glow. To have electricity, both an incoming current path and an outgoing current path must exist. Both must be defined for glowing to say anything useful.

It is a screw driver cum line tester.that is needed to connect only in 1 terminal and just touch the screw driver(line tester) to other end and the led will glow to show the presence of current.
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a b ) Power supply
May 11, 2011 6:28:24 PM

@ westom
You do not have to have the tester physically connected to both hot and common (Neutral) to test for the presence of a voltage. You can use the electrostactic field that is present. It is simular to holding a neon bulb close to a ac voltage the E-H field will ionize the neon and the bulb will glow without any current paths.

@ darksmart. This test only told you what you knew by touch. The single screwdriver type test only tells you that a voltage is present at a level high enough to ionize the lamp.

A little electricity 101
In US, for homes. Coming into the house we have two 120 voltAC hot and one Common (or neutral) wire. Half of the house connects to one of the Hot wires, the other Half connects to the other Half. The common goes to all of the house. The two Hot wires are 180 degress out of phase that is when one Hot is at a +170 V (120 x 1.414) the other hot is at -170V. If the House was perfectly balanced there would be current in both Hot wires and NONE in the common (neutral, or return) wire. For items requireing 240, both Hots are used with no return wire. +120 and -120 = 240 (NOT zero).
For England (here I am relying on OLD memory cells so should VERIFY) they use single phase (Not two Phase) so that you should have one hot, which is 240 and one Neutral. This means that both Hot and Neutral will have the same current.

Rather difficualt to explain without a diagrams, but here goes:
Say in next room you have something that is drawing 10 Amps and have a very low resistance between your common and ground. If that resistance is 0.1 ohms then you will see one volt on the neural line - if this reastance is 1 ohm then that would be 10V. This voltage would then be "reflected on other outlet's neutral lines.
Both countries use what is called 3-phase also that is where the volage waveforms are seperated by 120 degrees And uses 3 hot wires. This is most often used for industral use.

Just checked, my assumptions were correct: http://en.wikipedia.org/wiki/Electrical_wiring_in_the_U...

Bottom line - you need to dig further. (1) have you a wiring problem, or (2) a fault with the xbox power supply.
Time for that voltmeter and a quick learning section.

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a b ) Power supply
May 11, 2011 8:00:08 PM

darksmart said:
It is a screw driver cum line tester.that is needed to connect only in 1 terminal and just touch the screw driver(line tester) to other end and the led will glow to show the presence of current.

That tester only gives a subjective 'maybe'. Current can be flowing through the chassis while the voltage is near zero. To have a better answer, voltages needed. To better describe, for example, what causes a 'hot' chassis numbers. For example, what is the voltage from hot AC plug prong to safety ground. What is voltage from Xbox chassis to receptacle safety ground. Those numbers contain information you do not realize. And why RetiredChief also recommends that multimeter.

Better replies happen by first posting better facts. That typically means numbers.

Tester only implies an AC line filter is conducting current into the metal chassis. Information that already said so much more: you 'feel' a voltage.

Meanwhile, that AC power cord - only two wires - says the Xbox must have no exposed metallic parts. In some more primitive countries, that might be acceptable. But in first world nations, exposed metal means its power cord must have a three wire AC power cord.

And so a relevant and still unanswered question. Why is that only a two wire power cord?

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a b ) Power supply
May 11, 2011 10:08:18 PM

^ If you look at the Xbox PS - there is no prong for the ground. He could use a 3-wire AC cord, but would be no better than the 2-wire cord shown. What it is is Englands version of US 2-wire polarized plug.
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a b ) Power supply
May 11, 2011 10:35:19 PM

RetiredChief said:
What it is is Englands version of US 2-wire polarized plug.

I don't know if the United Kingdom ever had a two wire plug. Current three prong version (rectangular prong as shown) replaced a different three prong plug (round prongs) in the 1940s. US did not get around to three prong requirements until early 1960s.

If an appliance has exposed metal, then that chassis must connect to safety ground. Exceptions exist in the US. But again raises an unanswered question: why is that IEC power cord and connector only two prong?
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May 16, 2011 5:27:23 PM

Ok..First of all sorry for a late reply here..
What I did is connected a wire to a VGA cum composite cable of xbox 360 and inserted other end of this wire into the ground terminal of mains supply in the wall.and success, no current flowing through the console..Thats i think a temporary solution..
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May 22, 2011 5:17:29 PM

Best answer selected by darksmart.
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