I’m feeling a strange hum or light tingling feeling on my skin when I touch my computers

[bankruatsteve]

2 minutes ago, Bruce404 said:

    I think "UpToYoo" has a mistaken understanding of what residual current devices (RCDs), residual circuit breakers with overcurrent protection (RCBOs), and Ground Fault Circuit Interrupters (GFCIs, as termed in the USA) do and how they work. 

    It has nothing to do with leaking current going down a makeshift ground directly from the frame of an appliance, through the earth and retrograde from the formal grounding rod back up to the electrical panel/circuit board.

    Essentially the RCDs, RCBOs, and GFCIs measure both the currents "flowing out" on the Line ("hot") wire to an individual circuit and the Neutral wire "returning from" that circuit.  If they differ by more than a safe amount, the devices assume some of the current is passing unsafely through a human being or pet, and immediately break the circuit to stop any electrocution.  

    (Quotes are used around "flowing out" and "returning from", as for alternating current (AC), the electrons are changing direction to go back and forth either 50 or 60 times per second (Hertz = Hz) , depending on where in the world one's electrical supply is being generated.")

 

An earth fault is a current leak to ground via whatever path.  An RCD doesn't care what that path is (ground wire or human) and certainly doesn't assume anything.

[Bruce404]

Yes, "bankruatsteve" is correct.  "Assume" was too anthropomorphic a term to use to describe what these "smart" devices do.  Obviously, they have no idea what may be causing the differences in current between Line and Neutral.  They break the circuit regardless, as intended by their human inventors to protect life, and with little or no concern to save slightly on one's electrical bill if the leaky current is not large enough to trip the breaker, as it does when too much current flows.    

[bankruatsteve]

40 minutes ago, Bruce404 said:

They break the circuit regardless, as intended by their human inventors to protect life, and with little or no concern to save slightly on one's electrical bill if the leaky current is not large enough to trip the breaker, as it does when too much current flows.    

Your anthropomorphic strikes again.  Even if the RCD could be concerned, I doubt it would worry about a leak that, non-strop, would take over 6 days to accumulate 1 unit of energy.

 

Edit: corrected a wrong calculation.

[Uptooyoo]

3 hours ago, Bruce404 said:

    I think "UpToYoo" has a mistaken understanding of what residual current devices (RCDs), residual circuit breakers with overcurrent protection (RCBOs), and Ground Fault Circuit Interrupters (GFCIs, as termed in the USA) do and how they work. 

    It has nothing to do with leaking current going down a makeshift ground directly from the frame of an appliance, through the earth and retrograde from the formal grounding rod back up to the electrical panel/circuit board.

    Essentially the RCDs, RCBOs, and GFCIs measure both the currents "flowing out" on the Line ("hot") wire to an individual circuit and the Neutral wire "returning from" that circuit.  If they differ by more than a safe amount, the devices assume some of the current may be passing unsafely through a human being or pet, and immediately break the circuit to stop any electrocution.  

    Quotes are used around "flowing out" and "returning from", as for alternating current (AC), the electrons are actually changing direction to go back and forth either 50 or 60 times per second (Hertz = Hz) , depending on where in the world one's electrical supply is being generated.  Think of it like the Line wire is a straw with air like the electrical current:  the power company is quickly blowing air out and sucking air in on just the Line, and changing direction 50 or 60 times a second.  When an appliance or light is on, that "air" flows all the way to and from the planet earth below the house.  That's why one can safely touch a Neutral wire properly hooked up if the appliance or light is off.  But not ever a Line wire.

 

I did not address leakage current in my comment. And your assumption is that you have earth leakage protection to trip the main breaker or GFCI protection to trip the branch circuit breakers. My condo has none. As many don't in Thailand. In my country, GFCI protection does not preclude proper grounding according to the National Electrical Code. You say "When an appliance or light is on, that "air" flows all the way to and from the planet earth below the house." is totally incorrect. If that were the case earth leakage would be occurring all the time and the breakers would be tripped and could never be reset. Normal current flows between the secondary terminals of the transformer via your electrical distribution equipment. One of the transformer wires, the neutral, is earthed at the transformer and at the service panel to ensure the ground and neutral wires remain at earth potential. That's why you can touch the neutral wire and not get shocked. The only time that current flows to earth is if a person comes into contact with a shorted, ungrounded piece of equipment: they become the path to earth. This is when earth leakage protection is beneficial: the currents through the torroid sensor must algebraically equal zero; if not, current is leaking to ground, probably through a person and not returning through the torroid. The breaker senses this and trips the breaker. Earth leakage protection; however, does not maintain equipment at zero volts while the circuit is being tripped. Proper grounding does two things: it ensures that the equipment remains at zero volts and it provides a low resistance path to ensure enough current to trip a non-GFCI breaker.

[bankruatsteve]

20 minutes ago, Uptooyoo said:

Proper grounding does two things: it ensures that the equipment remains at zero volts and it provides a low resistance path to ensure enough current to trip a non-GFCI breaker.

It seems obvious that you are relating electrical experience from the states and assuming the same here.  It isn't relative to the distribution system. 

 

An earth fault is just that.  One wants the fault to travel via the ground wire instead of through a body.  The fault can be microamps or dozens of amps.  Grounding does nothing to determine the size of fault current (per se), it just gives it a "safe" path to ground.  An RCD (GFCI, etc) trips on faults over 30ma no matter what the path to ground.  That's a long way from a 20a over-current breaker.  

[Uptooyoo]

3 hours ago, bankruatsteve said:

An earth fault is a current leak to ground via whatever path.  An RCD doesn't care what that path is (ground wire or human) and certainly doesn't assume anything.

Yes, but its purpose is to save lives....which usually involves a human.

[anterian]

I always have problems sorting out leakage currents, after 80 years of frequent exposure I find them difficult to detect. However, I have discovered that the average female is an even more sensitive indicator than even a neon screwdriver. But then the striking voltage for a neon is 90 volts and some women I have met can even feel the 12 volts of a car battery. 

[bankruatsteve]

7 minutes ago, Uptooyoo said:

Yes, but its purpose is to save lives....which usually involves a human.

We can agree to that for sure.  ????

[Uptooyoo]

22 minutes ago, bankruatsteve said:

It seems obvious that you are relating electrical experience from the states and assuming the same here.  It isn't.  An earth fault is just that.  One wants the fault to travel via the ground wire instead of through a body.  The fault can be microamps or dozens of amps.  Grounding does nothing to determine the size of fault current (per se), it just gives it a "safe" path to ground.  An RCD (GFCI, etc) trips on faults over 30ma no matter what the path to ground.  That's a long way from a 20a over-current breaker.  

That's why there is a hard ground connection (green wire) so that more than 20 amps will flow, tripping the breaker. RCBO is added protection. Look at the panel below. It's split between non leakage protection and leakage protection. All circuits are grounded with a green wire back to the ground bar, even if it is earth leakage protected. Note the MEN link. It's purpose is to complete the path from the main earth bar to the main neutral bar completing the low resistance path back to the transformer so the standard, non-leakage breaker will trip if the ELCB breaker should fail. This panel is found in Thailand.

[bankruatsteve]

4 minutes ago, anterian said:

I always have problems sorting out leakage currents, after 80 years of frequent exposure I find them difficult to detect. However, I have discovered that the average female is an even more sensitive indicator than even a neon screwdriver. But then the striking voltage for a neon is 90 volts and some women I have met can even feel the 12 volts of a car battery. 

Women more sensitive than guys?  I think you might be on to something there.  ????

 

[bankruatsteve]

3 minutes ago, Uptooyoo said:

That's why there is a hard ground connection (green wire) so that more than 20 amps will flow, tripping the breaker.

If you are saying fault current is always 20a or more, I'll say you are mistaken.  Or, what are you saying?  There are some distribution types in Thailand where a 20a fault to ground, through a ground wire, will not trip the breaker.

[Bruce404]

    This is In response to "Uptooyoo" writing that "You say 'When an appliance or light is on, that "air" flows all the way to and from the planet earth below the house.' is totally incorrect."

   There appears to be some terminological mis-interpretation of intended meanings going on in these back-and-forths, perhaps due to different usage of the word "earth" (a.k.a. "ground" in USA and elsewhere) between technicians and laypersons.

    As is many countries, Thailand standards follow a Multiple-Earthed Neutral (MEN) practice, in which there are many connections in the system between the wires designated as NEUTRAL and the wires designated as EARTH (or GROUND is U.S. parlance):  e.g., in the circuit-breaker panel box, at the company's power pole supplying the drop to the customer's wiring, and elsewhere in the system from power plant to consumer).   http://www.electricalaxis.com/2016/10/what-is-multiple-earthed-neutral.html 

    Thus, one cannot really know exactly what proportions of the electrons being "pushed" or "pulled" by the power company in the wiring designated as LINE are returning to or coming from the "planet earth", i.e., the soil underneath us all, in both the NEUTRAL or EARTH wires.  Certainly both.

    In my simple analogy to explain to those unfamiliar with electrical systems, when a power company is blowing out or sucking in "air" through a straw (i.e., pushing or pulling electrons via LINE wires) to an activated light bulb or appliance (termed a LOAD), that "air" (electrons) is/are going to or coming from -- on the other side of the LOAD -- the planet earth beneath our feet. 

    So it is confusing and wrong for Uptooyoo to write that "The only time that current flows to earth is if a person comes into contact with a shorted, ungrounded piece of equipment: they become the path to earth."  And this applies to both meanings he might have meant for the word "earth": (1) the wiring formally designated as "EARTH" (because electrically-joined in multiple places to wires designated as NEUTRAL), and (2) to the "earth" (the soil beneath our feet, our buildings, our power poles, our earthing/grounding rods, etc.).

     

[Uptooyoo]

25 minutes ago, Bruce404 said:

    This is In response to "Uptooyoo" writing that "You say 'When an appliance or light is on, that "air" flows all the way to and from the planet earth below the house.' is totally incorrect."

   There appears to be some terminological mis-interpretation of intended meanings going on in these back-and-forths, perhaps due to different usage of the word "earth" (a.k.a. "ground" in USA and elsewhere) between technicians and laypersons.

    As is many countries, Thailand standards follow a Multiple-Earthed Neutral (MEN) practice, in which there are many connections in the system between the wires designated as NEUTRAL and the wires designated as EARTH (or GROUND is U.S. parlance):  e.g., in the circuit-breaker panel box, at the company's power pole supplying the drop to the customer's wiring, and elsewhere in the system from power plant to consumer).   http://www.electricalaxis.com/2016/10/what-is-multiple-earthed-neutral.html 

    Thus, one cannot really know exactly what proportions of the electrons being "pushed" or "pulled" by the power company in the wiring designated as LINE are returning to or coming from the "planet earth", i.e., the soil underneath us all, in both the NEUTRAL or EARTH wires.  Certainly both.

    In my simple analogy to explain to those unfamiliar with electrical systems, when a power company is blowing out or sucking in "air" through a straw (i.e., pushing or pulling electrons via LINE wires) to an activated light bulb or appliance (termed a LOAD), that "air" (electrons) is/are going to or coming from -- on the other side of the LOAD -- the planet earth beneath our feet. 

    So it is confusing and wrong for Uptooyoo to write that "The only time that current flows to earth is if a person comes into contact with a shorted, ungrounded piece of equipment: they become the path to earth."  And this applies to both meanings he might have meant for the word "earth": (1) the wiring formally designated as "EARTH" (because electrically-joined in multiple places to wires designated as NEUTRAL), and (2) to the "earth" (the soil beneath our feet, our buildings, our power poles, our earthing/grounding rods, etc. 

     

Normal current flow in a circuit does not flow through the physical earth, dirt, ground rod, only through the neutral wire. I should have said normal current. Stray currents, earth leakage currents are not desired or normal currents. The earth, the dirt that is, is not an intended conductor for current flow. The neutral wire is the desired conductor for current flow, if there is a short to the appliances frame, the green ground wire carries the current. And yes it will be way more than the breakers rating and it will trip. The formula is Current= Voltage/resistance. Lets say .5 ohms of resistance. 460 amps of current will flow to trip the 20 amp breaker.

 

[Crossy]

3 minutes ago, Uptooyoo said:

Normal current flow in a circuit does not flow through ground, only through the neutral wire. I should have said normal. Stray currents, earth leakage are not desired or normal currents.

 

Just to muddy the waters. One of the issues with TNC-S (MEN or PME) is diverted neutral currents. Even with an intact neutral some of the neutral current flows in the ground. Think of it as two parallel resistors, even if one is 1000 times bigger than the other some current flows in the larger.  

 

This is why (at least in the UK) the main earth connection must be relatively massive.

 

[Bruce404]

3 minutes ago, Uptooyoo said:

Normal current flow in a circuit does not flow through ground, only through the neutral wire.

    This statement by "Uptooyoo" ONLY applies in a properly functioning LOAD (light bulb and appliance) between that bulb or appliance and the closest circuit-breaker/panel box. 

    At that location, in most places worldwide, the NEUTRAL bars and EARTH/GROUND bars are bonded to each other, and thus share the transmission of electrons to and from planet earth in unknowable (although experimentally-measurable) proportions.   

[Crossy]

@Bruce404 it seems great minds think alike ????

 

The exact format of the N-E link varies, but the vast majority of the 3-phase, 4-wire, 220V world uses some variant of TNC-S (MEN).

 

[Uptooyoo]

4 minutes ago, Crossy said:

@Bruce404 it seems great minds think alike ????

 

The exact format of the N-E link varies, but the vast majority of the 3-phase, 4-wire, 220V world uses some variant of TNC-S (MEN).

 

3-phase, 4 wire is normally supplied to industrial and commercial establishments. The secondary of the transformer is WYE connected with the center forming the neutral which is bonded to structural steel and the grounding grid embedded in the concrete foundation. Line to line voltage is 1.73 times the Line to Neutral voltage. Stateside it's 480/277 and 208/120 volts in most commercial and industrial buildings

[bankruatsteve]

2 minutes ago, Uptooyoo said:

3-phase, 4 wire is normally supplied to industrial and commercial establishments. The secondary of the transformer is WYE connected with the center forming the neutral which is bonded to structural steel and the grounding grid embedded in the concrete foundation. Line to line voltage is 1.73 times the Line to Neutral voltage. Stateside it's 480/277 and 208/120 volts in most commercial and industrial buildings

Aargh.  Like I tried to tell you previously, the states distribution system IS NOT USED in Thailand (or just about anywhere else in the world).  It is not relevant to anything here.

[Crossy]

5 minutes ago, Uptooyoo said:

3-phase, 4 wire is normally supplied to industrial and commercial establishments.

 

Here in sunny Thailand every home is supplied from 1 phase and the neutral of a 3-phase, 4-wire, 220/380V system. Big homes (needing more than about 10kW) have all three phases plus the neutral.

 

Take a look at the poles outside your home, there will likely be 4 LV wires on small insulators, the top (bare) one is the neutral the lower three the phases. Your house will be supplied from the neutral and one of the phases.

 

It is important to understand that this is NOT the US system.

[Bruce404]

17 minutes ago, Crossy said:

The exact format of the N-E link varies, but the vast majority of the 3-phase, 4-wire, 220V world uses some variant of TNC-S (MEN).

For the benefit of those not familiar with the jargon of electrical professionals, here is where "TNC-S" and "MEN" are explained:

https://en.wikipedia.org/wiki/Earthing_system#Types_of_TN_networks 

[Bruce404]

I really have to get back to homework and stop procrastinating with commenting on electrical-system matters.

     I am neither electrical engineer nor current- or ex-licensed professional electrician, although familiar with codes and experienced doing jobs carefully and correctly that would pass inspection. 

    So here's my last comment:  a hypothetical and a question for the pros on this forum to respond, if they care to weigh in.

      A modest dwelling, in Thailand say, has a properly-wired 15 amp (45A max) single-phase system with an excellent, well-functioning earthing/grounding setup with its copper rod connected by a 2-meter-long, 6-mm² cross-sectional-area wire to the EARTH/GROUND bar in the panel.

    In the panel, the EARTH/GROUND bar is well-connected by a code-sized bonding wire to the NEUTRAL bar.

     The next-closest earthing/grounding connection for the NEUTRAL wire is, say, 250 meters away at the base of the PEA's power pole on the street with its transformer atop, and similarly functions properly.  The cross-sectional areas of the LINE and NEUTRAL wires heading to the power pole are the minimum that Thai code would require for such a setup.  

     One turns on a LOAD, and uses an ammeter within the panel box to clamp around and measure how much current the EARTH/GROUND wire is carrying 2 meters to the rod in planet earth, and also how much current the NEUTRAL wire is carrying 250 meters to the PEA transformer.

    What proportions of the total current would you guess are carried by each wire? 

     Beyond just guessing, pros with ammeters could actually provide measured empirical findings from their own panels, although likely with quite different distances and wire sizes than this thought experiment. 

 

[bankruatsteve]

In my case, I don't need to guess.  Current on N is the same as L leaving E with 0.  I do not have "MEN" and can't remember the term, but it's what most of up-country has.  And, yes, this has been measured with quality ammeter.

[Fruit Trader]

55 minutes ago, Bruce404 said:

I really have to get back to homework and stop procrastinating with commenting on electrical-system matters.

     I am neither electrical engineer nor current- or ex-licensed professional electrician, although familiar with codes and experienced doing jobs carefully and correctly that would pass inspection. 

    So here's my last comment:  a hypothetical and a question for the pros on this forum to respond, if they care to weigh in.

      A modest dwelling, in Thailand say, has a properly-wired 15 amp (45A max) single-phase system with an excellent, well-functioning earthing/grounding setup with its copper rod connected by a 2-meter-long, 6-mm² cross-sectional-area wire to the EARTH/GROUND bar in the panel.

    In the panel, the EARTH/GROUND bar is well-connected by a code-sized bonding wire to the NEUTRAL bar.

     The next-closest earthing/grounding connection for the NEUTRAL wire is, say, 250 meters away at the base of the PEA's power pole on the street with its transformer atop, and similarly functions properly.  The cross-sectional areas of the LINE and NEUTRAL wires heading to the power pole are the minimum that Thai code would require for such a setup.  

     One turns on a LOAD, and uses an ammeter within the panel box to clamp around and measure how much current the EARTH/GROUND wire is carrying 2 meters to the rod in planet earth, and also how much current the NEUTRAL wire is carrying 250 meters to the PEA transformer.

    What proportions of the total current would you guess are carried by each wire? 

     Beyond just guessing, pros with ammeters could actually provide measured empirical findings from their own panels, although likely with quite different distances and wire sizes than this thought experiment. 

 

First off, if the the transformer is the only other ground point for neutral then its no longer a combined neutral and multiple earth conductor before it arrives at the service.

 

In simple terms the value of R1 and R2 below will determine current flow.

 

[Wirejerker]

Bruce404 & uptooyou
It’s refreshing to hear from you who understand the principles but you must realise when others Piss into the wind it’s time to step back as it’s a sure thing what’s coming back.


Sent from my iPad using Tapatalk

[Uptooyoo]

8 hours ago, Crossy said:

 

Here in sunny Thailand every home is supplied from 1 phase and the neutral of a 3-phase, 4-wire, 220/380V system. Big homes (needing more than about 10kW) have all three phases plus the neutral.

 

Take a look at the poles outside your home, there will likely be 4 LV wires on small insulators, the top (bare) one is the neutral the lower three the phases. Your house will be supplied from the neutral and one of the phases.

 

It is important to understand that this is NOT the US system.

That's why I said "stateside." I never claimed it was in Thailand.

[Crossy]

10 hours ago, bankruatsteve said:

I do not have "MEN" and can't remember the term, but it's what most of up-country has. 

 

It's "TT".

 

Bruce linked to the Wiki page earlier https://en.wikipedia.org/wiki/Earthing_system#Types_of_TN_networks 

 

[Crossy]

4 hours ago, Uptooyoo said:

That's why I said "stateside." I never claimed it was in Thailand.

 

Indeed, but I was responding to this statement "3-phase, 4 wire is normally supplied to industrial and commercial establishments." which is incorrect for Thailand (and the UK, Aus and many other locations) where all villages (except the really small ones) are wired 3-phase, 4-wire with each user picking off a phase and neutral.

 

Got a small factory? PEA will add two wires and give you 3-phase, no mucking about with more transformers and the like.

[Uptooyoo]

16 hours ago, Bruce404 said:

For the benefit of those not familiar with the jargon of electrical professionals, here is where "TNC-S" and "MEN" are explained:

https://en.wikipedia.org/wiki/Earthing_system#Types_of_TN_networks 

TNC-S is what is used in the U.S. and Canada.

[Uptooyoo]

My original post was to address the danger of grounding electrical equipment by attaching the appliance to earth (ground rod. hole drilled in the concrete floor) without using the ground wire at the receptacle. The ensuing conversation then went off the rails in so many directions. Attached is a picture showing why you must have a ground wire and not rely on an earth-only connection. The breaker will not operate to remove the lethal voltage on the appliance's frame. I AM NOT ADDRESSING GROUND FAULT PROTECTION FOR PERSONNEL! E.G. RCBO, etc.

 

Watch the first part of this video up to 2:30. https://binged.it/2Zbwf29

 

The reason why you need a ground wire.

[Crossy]

1 hour ago, Uptooyoo said:

without using the ground wire at the receptacle.

 

If there's already a ground at the outlet, one won't be needing to drill holes in the floor (or did I miss that post).

 

You will notice that the excellent Mike Holt video shows the NEC method for TNC-S (MEN) with a solid metallic path right back to the star point.

 

Without the N-E link a rod alone will indeed not open an MCB, hence the need for an RCBO in addition to the rod.