Adding your own earth won't make things safer. In the UK, earth and neutral are tied together at the electricity substation and the purpose of earthing the conductive chassis of an appliance is so that if a live wire contacts the chassis, it effectively touched neutral and a large enough fault current flows to blow the fuse. If you add an earth to a system that doesn't have neutral bonded to earth (I've no idea whether your country has that), you won't have achieved safety.
Making your own connection to planet Earth can have all sorts of consequences. Suppose that connection comes into contact with your electricity supply company's earth connection? The two will almost certainly not be at the same potential, but you both strove for zero source impedance. A very large current will flow. And you won't know until the smoke starts pouring out.
Just use an isolating transformer.
Making your own connection to planet Earth can have all sorts of consequences. Suppose that connection comes into contact with your electricity supply company's earth connection? The two will almost certainly not be at the same potential, but you both strove for zero source impedance. A very large current will flow. And you won't know until the smoke starts pouring out.
Just use an isolating transformer.
Seldom do electricians that are in residential work have the specialized test equipment or the time to measure the earth resistance. So they just add a second ground rod and collect their money.
I think for electrical safety - A safety ground as tied ONLY to neutral at the incoming panel assures that it is indeed the lowest potential available in that dwelling. Assuming that no currents (excepting faults and leakage) are allowed. The Earthing or ground rod at the panel is mostly for Lightning and radio applications which may/should be required for any overhead lines including CTV and telephones.
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I don't know about other countries either, so I'll just talk about parts of the US (California, Idaho, Alaska) where I have knowledge of the electrical code and practices.
The electric utility does *NOT* bring a separate safety grounding connection to your house. There is a ground*ed* conductor, also called a "neutral", which is likely grounded but not depended upon for safety ground.
The safety ground in your house is provided by a metallic connection to earth at your house (ground rod, though water pipes were commponly used also) which is "bonded", or electrically connected, to the neutral at exactly one point in your house. This is basically a star ground system to insure that any fault currents are returned to the bonding point and do not appear on exposed conductive parts of the faulty equipment or other innocent equipment connected to the same AC supply.
The reason for never ever connecting a current carrying conductor (e.g. neutral) to your amp chassis is because it will defeat your safety grounding system, allowing fault current anywhere in your house to cause a dangerous voltage to potentially (;-) appear on your amp chassis, or faults in your amp to energize other equipment (like the toaster your kid is using).
The circuit posted at the beginning of this thread WILL energize the chassis if it doesn't trip the breaker first.
Also, the suggestion to use a GFI or ELCB with an autotransformer is illegal in this country and dangerous everywhere. YOU MUST HAVE ISOLATION BETWEEN THE AC CURRENT CARRYING CONDUCTORS AND ANY EXPOSED METAL PARTS!!! PERIOD!!!
Just don't even consider anything else.
The misinformation in this thread is scary...
Stay alive and keep your cohabitants alive
Michael
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Your home 220V/50HZ, to pass an inspection must have the three conductor instalation: Brown(live), Blue(neutral) and Yellow/green (safety cord) and a earth ground take at one point whith a copper rod (jabalina de puesta a tierra) And a differential circuit breaker where the fuses box.
EXAPOWER - Fabrica de Jabalinas de puesta a tierra y complementos, galvanoplastia , equipos rectificadores, lineas automáticas, accesorios para líneas y productos químicos. Sulfato de níquel, cobre...
should be, at least according to the regulations now in effect
EXAPOWER - Fabrica de Jabalinas de puesta a tierra y complementos, galvanoplastia , equipos rectificadores, lineas automáticas, accesorios para líneas y productos químicos. Sulfato de níquel, cobre...
should be, at least according to the regulations now in effect
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I live in a newer Calif tract home with underground utilities and there was NO earth connection to a ground rod or any other pipe to the safety ground bus on my 200A panel. I'm sure it's built per CA code in my city. Altho I did add it on my own to the natural gas pipe at ground level. All my neighbors are without. I'm assuming it was not required because it is all underground ie no lightning strikes.
Because it's not totally reliable - it is a mechanical system after all. The isolation properties of transformers are far more reliable. Also, an ELCB might not trip in a situation where your amplifier starts blowing up connected equipment.
Another reason for avoiding autotransformers is the possibility of reversing live and neutral. Assuming that the neutral of the power supply is connected to the chassis of the amplifier, doing so with no isolation means that the chassis of your equipment will become live. This is especially important in situations where there is no safety earth to connect to the chassis.
No Grounds!
I just pulled the "new" outlets... installed when we did the remodel of our kitchen some three years ago or so.......No ground connections.The rest of the outlets "old style" two conductor.
I only have two lines coming inside the house to the TWO Breakers, about 12 gauge STRANDED....another 15 feet to another pair of breakers outside..the outside breakers are "free floating" suspended by the incoming solids, then to the Meter.
The "Power pole" across the street is a virtual rats nest of inter-connects....something seen in NYC at the turn of the century!
Ho boy....what a holy nightmare. We live in an upscale part of town...& you don't even WANT to know what buggered up wiring I've seen out in the boonies!
__________________________________________________Rick.....
I just pulled the "new" outlets... installed when we did the remodel of our kitchen some three years ago or so.......No ground connections.The rest of the outlets "old style" two conductor.
I only have two lines coming inside the house to the TWO Breakers, about 12 gauge STRANDED....another 15 feet to another pair of breakers outside..the outside breakers are "free floating" suspended by the incoming solids, then to the Meter.
The "Power pole" across the street is a virtual rats nest of inter-connects....something seen in NYC at the turn of the century!
Ho boy....what a holy nightmare. We live in an upscale part of town...& you don't even WANT to know what buggered up wiring I've seen out in the boonies!
__________________________________________________Rick.....
Are you out of your mind?
You've provided a path to ground for lightning strikes at the effing gas main. BOOM!! 
Ground to the main side of your water meter.
I wonder if your developer bribed somebody. NEMA rules were not followed. NYC's electricity distributor, Con Edison, has much of their wiring under ground. You can bank on proper safety grounding in the "Big Apple".
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so u have single phase 240V both hot ie No Neutral. Then it's uncertain by adding a ground rod that it can take a full fault current since it's unlikely that the transformer is even grounded?
No, it is 220V, and using one of these fase check screwdrivers is easy to see that one is the live and the other neutral.
When I come back and become the President , a lot of things will change...
It's not a surprise to see the setup in a "240" V. zone resemble that of North America's "120" V. The n-earth-n arrangement, at the distribution trafo, is flexible and it allows for some power factor "monkey business".
Regardless of history
Eli is right about your gas main, it's illegal under NEMA (I have a recent copy) to connect it or use it as a house ground and I bet that there is a ground somewhere in your house that you cannot see. (It may be under your slab - a common practice here less than 30yrs ago) Possibly there is a communal ground, but I suspect there should be one at each house as well. Our pole pigs are all grounded directly by a rod at the pole they are installed on - there is also a grounding conductor that runs along the top of the pole tree although I am not sure this shares common grounds with the residential system. (I kind of hope not) We have 22kV distribution here according to our local inspector.Here I have two ground rods (required here due to soil conductivity) at the house, the water supply is bonded to the neutral/safety ground in the panel. The gas line is not bonded although I assume both our stove and new gas steam boiler with electronic controls effectively ground the gas line to the house grounds. Note that there is also a potential issue with electrolysis if you bond house ground to your gas line, that is one of the reasons it's not recommended in addition to potential issues with lightening safety. Basically nearby strikes may generate potential differences of 10kV/ft or more in the ground the gas pipe traverses regardless of what is connected to the gas main so I think this is a mostly a secondary issue with bonding, corrosion being the more major one.. We took a more or less direct hit on the house 3 summers ago, sustained no significant damage except to the electronics in my car parked 30' away in the garage.. EMP I guess
Massive electronic malfunctions in several unrelated systems in the car the very next day.. My house has grounded aluminum siding which apparently is a pretty effective faraday cage.
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@Infinia,
I feel compelled to mention that just because wiring is installed underground does not mean it is completely safe against a random lightening strike - this is something of a myth. Large gauge power cables generally have lower resistivity than the soil around them and should there be a nearby strike lightening will happily follow them until it finds a lower impedance ground - some times with quite catastrophic consequences if that ground happens to be somewhere inside your house or your well should you have one.. It's one of the leading causes of pump failure in domestic deep wells. (Several of my friends down South with underground utilities can probably attest to this.) As far as wells are concerned when I lived in the woods most of my neighbors over time lost their well pumps to nearby lightening strikes - I was lucky, mine just wore out..
I feel compelled to mention that just because wiring is installed underground does not mean it is completely safe against a random lightening strike - this is something of a myth. Large gauge power cables generally have lower resistivity than the soil around them and should there be a nearby strike lightening will happily follow them until it finds a lower impedance ground - some times with quite catastrophic consequences if that ground happens to be somewhere inside your house or your well should you have one.. It's one of the leading causes of pump failure in domestic deep wells. (Several of my friends down South with underground utilities can probably attest to this.) As far as wells are concerned when I lived in the woods most of my neighbors over time lost their well pumps to nearby lightening strikes - I was lucky, mine just wore out..
This thread is scary. Lot’s of suspect information here. Hire a professional, people!
Some types of gas pipe such as CSST (Corrugated Stainless Steel Tubing) REQUIRES bonding as shown here: http://www.gastite.com/include/languages/english/downloads/pdfs/Gastite_LightningSafety_General.pdf
CSST punctures have occurred during a lighting strike due to arcing from a bonded system to unbonded CSST. So CSST must be properly bonded to minimize the risk.
While it is correct that the gas pipe cannot be used as a "house ground", Section 250.104(B) states that all metal pipe systems within a dwelling "...including gas piping, that may become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to one or more grounding electrodes used." This includes bonding of water pipes, metal pipes used for compressed air distribution in a workshop, conduit and metal gas pipes. Gas pipe is usually bonded via the gas appliance (furnace, stove).
Most gas companies use dielectric unions on the meter side to protect the gas mains from electrolysis driven corrosion.
Note that I am not a licensed plumber or electrician.
Are you out of your mind?
Some types of gas pipe such as CSST (Corrugated Stainless Steel Tubing) REQUIRES bonding as shown here: http://www.gastite.com/include/languages/english/downloads/pdfs/Gastite_LightningSafety_General.pdf
CSST punctures have occurred during a lighting strike due to arcing from a bonded system to unbonded CSST. So CSST must be properly bonded to minimize the risk.
Regardless of history
While it is correct that the gas pipe cannot be used as a "house ground", Section 250.104(B) states that all metal pipe systems within a dwelling "...including gas piping, that may become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to one or more grounding electrodes used." This includes bonding of water pipes, metal pipes used for compressed air distribution in a workshop, conduit and metal gas pipes. Gas pipe is usually bonded via the gas appliance (furnace, stove).
Most gas companies use dielectric unions on the meter side to protect the gas mains from electrolysis driven corrosion.
Note that I am not a licensed plumber or electrician.
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Regardless of history
I'm glad you chimed in
Maybe you can read us what NEMA says about earth bonding to neutral. Is there a requirement for wire size and length of run and so on... AFTER the residence meter via underground distribution??
All I'm saying is what I see in my house regarding an actual earth ground, Believe me it's not hidden. I can see every thing from the slab incoming PVC conduit with 2 phase + neutral up to the 200A meter and everything connected to the panel itself. I think the actual bonding to earth is supplied at via the secondary neutral at the 8K Volt distr transformer. All distribution is in underground vaults for all three phases supplying about 800 residences. Any lightning is susceptible at least 2 transformers back so the major damage would surely be back there.
We just had all our meters gas+elect converted to smart ones, so I'm sure if my gas ground connection was verboten they would of pulled it. I used 12AWG solid to the panel enclosure.
So then it would be easier (relatively) and safer to convert from 2 wire to 3 wire?
Humor it's good!
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