Everyone is talking about grounding isues. And I am just siting here in block of flats without any grounding in any socket. I wonder why there is no safety earth. This buiding 26 years old... Only place where i saw safety earth was in my uncles new house.
Atleast I don't have hum problems
And don't need to bother with those huge power sockets in my amps, just nice little philips sockets, and flexible wires haha.
"Nicest" thing are those caps from L and N to Safety earth in power supplies of PCs or any supply with that "noise" filter. It makes loads of noise when two devices with safety earths connected through power strip. Power strips sold here all are with safety earth... Total noise machines when socket itself is not earthed.
To people talking about lack of earthing and death like guaranteed combination: Thank you, it is really fun to read. If that was true, 1/3 of Lithuania would be dead already...
Before someone starts saying something, remember that i would like to have earthed sockets, but I can't...
Atleast I don't have hum problems
And don't need to bother with those huge power sockets in my amps, just nice little philips sockets, and flexible wires haha."Nicest" thing are those caps from L and N to Safety earth in power supplies of PCs or any supply with that "noise" filter. It makes loads of noise when two devices with safety earths connected through power strip. Power strips sold here all are with safety earth... Total noise machines when socket itself is not earthed.
To people talking about lack of earthing and death like guaranteed combination: Thank you
, it is really fun to read. If that was true, 1/3 of Lithuania would be dead already...Before someone starts saying something, remember that i would like to have earthed sockets, but I can't...
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'Grounding' is a term used in audio electronics for two quite different things:
1. Putting a piece of metal between users and live conductors, arranged in such a way that if any of the live conductors touch the metal a fuse/trip is blown so the user remains safe.
2. Choosing a reference point for signal voltages in the circuit, and ensuring that all signal voltages actually use that reference point and not something which looks superficially the same but is not.
Given that the same name is used for both, it is not surprising that people often confuse them. The name of this thread is "understanding star grounding"; this clearly refers to ground no. 2 in my short list above.
1. Putting a piece of metal between users and live conductors, arranged in such a way that if any of the live conductors touch the metal a fuse/trip is blown so the user remains safe.
2. Choosing a reference point for signal voltages in the circuit, and ensuring that all signal voltages actually use that reference point and not something which looks superficially the same but is not.
Given that the same name is used for both, it is not surprising that people often confuse them. The name of this thread is "understanding star grounding"; this clearly refers to ground no. 2 in my short list above.
Some common types of 'ground'.
a] Safety Ground/Protective Earth, to trip the circuit breaker if there is a short (fault).
b] Ground Rod, the stake in the garden. For protect during thunderstorms and other events.
c] Audio circuit or power supply common.
Note that all of these are connected together, but each has it's own task.
In the US, older 2 wire homes can add a Ground Fault Current Interrupter (GFCI) receptacle for safety.
a] Safety Ground/Protective Earth, to trip the circuit breaker if there is a short (fault).
b] Ground Rod, the stake in the garden. For protect during thunderstorms and other events.
c] Audio circuit or power supply common.
Note that all of these are connected together, but each has it's own task.
In the US, older 2 wire homes can add a Ground Fault Current Interrupter (GFCI) receptacle for safety.
A GFCI is useless without a earth ground connection. they call it a ground fault detector for a reason.
If the GFCI for the circuit is in the distribution box okay, but not a recepticle type gfci, without it being connected back to earth ground.
It is designed to sense earth ground current, the stuff that will stop your heart/electrocution, in the single digit mA range. the current return path from the line is supposed to flow in the neutral conductor, not the earth ground conductor. any current flowing in the earth ground connection is a ground fault by definition. an example is you touching a live conductor and your body is conducting the electric to earth ground. without the device being able to sense ground current it will not work as intended.
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Actually that is an earth leakage circuit breaker, a modern GFCI (In American usage) is a Residual Current Circuit Breaker (RCD in UK terminology) and does NOT require a ground connection to function as it measures only the difference between current on the line and neutral conductors (Current taking **ANY** other path (Like say via your body to earth) will trip the breaker).
That said, the US does have a scarily casual approach to electrical system design in some ways.
Star earthing should have **NOTHING** to do with how the electrical safety bonding is handled.
Regards, Dan.
That said, the US does have a scarily casual approach to electrical system design in some ways.
Star earthing should have **NOTHING** to do with how the electrical safety bonding is handled.
Regards, Dan.
Dmills is correct. A GFCI will work (trip due to ground fault currents greater than 5 mA) without the earth ground connection.
In the USA, they are required to trip if the difference between hot and neutral currents is nominally greater than 5 mA.
Any current flowing through the ground connection is not called a ground fault current by definition, it is called nuisance current. It is not defined as a dangerous current per se, and typical USA load panels do NOT measure, monitor, nor make any decisions whatsoever if there is lots of current within the grounding conductor.
The only purpose of the grounding conductor is to prevent the energization of grounded surfaces of equipment by forcing excessive currents in the hot conductor of the circuit, thereby forcing the line protection device (fuse or breaker) to trip instead of leaving surfaces hot to touch. That effort to maintain surfaces non lethal (50 volts) is the reason any device designed to break that connection at 60 hz is against code, the impedance to ground must be low to force the breaker to trip. I believe the timeframe is two line cycles, which requires sufficient current to magnetically trip the breaker, not thermally.
The easiest way to monitor this difference is to run both the hot and neutral pair through a small toroid 5 to 7 times in the same winding direction. The toroid will subtract the two, and a secondary on the toroid is used to see the difference.
I also have to laugh at the "lethal current". Over the years, it has waffled between 2 mA, 5 mA, 10 mA, and 60mA, with the higher currents lately introduced when AC and DC were split out. I believe I just took a course where it is now 1 mA..sigh.. I did not have the heart to disagree with the presenter, he was only a messenger.
The old two blade plugs and sockets require the neutral blade be the larger of the two, and that light sockets have the neutral connected to the threaded base portion, that will easily be touched during bulb installation so should always be the neutral. I suspect that there is also a requirement that the smaller blade (hot) be the switched and fused wire (if the equipment has a fuse). Hot switch is a requirement nowadays by code. Neutral switching on a lamp fixture will allow the screw base to become energized once a bulb has contacted the center connection, and the user could be electrocuted through the bulb filament.
John
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Really? You guys on the other side of the pond have double the voltage and you point at us??? I'm scared just pluggin stuff in over there..
I will admit I hate the single bushing design on the east coast, but what other things about us do you not like? Let's keep "english language" outta this, shall we??
John
okay, i guess we got that cleared up and extras to boot. thx for the education
I know where I live, they have added to the code, arc-fault breakers for all bedrooms and even yellow? jacketed nmd90, made for little man sticking his fingers,toys in the bedroom receptacle.
Now CO and smoke alarms mandatory, all smoke alarms must signal each other. A friend had a new house built this year, we tested the fire alarm system what a racket of noise,flashing strobe lights, wow, designed to wake up the dead from what I experienced.
any examples of scary casual electrical system over here in N/A that we should look out for specifically?
I know where I live, they have added to the code, arc-fault breakers for all bedrooms and even yellow? jacketed nmd90, made for little man sticking his fingers,toys in the bedroom receptacle.
Now CO and smoke alarms mandatory, all smoke alarms must signal each other. A friend had a new house built this year, we tested the fire alarm system what a racket of noise,flashing strobe lights, wow, designed to wake up the dead from what I experienced.
Lets see, scary ****....
Bootleg 'grounds' (Connecting ground and neutral at the outlet because you don't have a real ground available, what could possibly go wrong, and yes this is a thing)!
Locally grounded medium voltage neutrals (as in the primary side of pole pigs), makes life 'interesting' when the upstream neutral comes adrift, and particularly in rural areas there is lots of medium voltage distro running single phase (Worst case for this).
'Wire Nuts'.
An extreme reluctance to upgrade stupidly old installations (Knob and tube should have been ripped out 30 odd years back, everywhere).
The fact that the 'Cheater plug' is a thing (And that by implication ungrounded outlets have not been ripped out during a routine upgrade in the last 30 odd years exist in enough locations to make selling them at home depot worthwhile).
Clothes driers and similar loads running from two legs of a split phase supply, with the ancillary 120V loads returned to the GROUND pin because neutral was not available, this was broken when it was first done, and should just be illegal.
None of these things would come even close to passing the sniff test in the UK.
Also, what is it with the fondness for overhead distro in cities (It makes sense in low density rural areas), it is visually a mess, prone to pick up any thunderstorm going, and probably materially less reliable then putting it underground (Which I will grant is a higher capital cost option).
All this, and you still cannot get enough juice out of a kitchen socket to boil a kettle in reasonable time (UK kettles are typically 2.5 or 3KW, we likes our tea!).
Regards, Dan.
Bootleg 'grounds' (Connecting ground and neutral at the outlet because you don't have a real ground available, what could possibly go wrong, and yes this is a thing)!
Locally grounded medium voltage neutrals (as in the primary side of pole pigs), makes life 'interesting' when the upstream neutral comes adrift, and particularly in rural areas there is lots of medium voltage distro running single phase (Worst case for this).
'Wire Nuts'.
An extreme reluctance to upgrade stupidly old installations (Knob and tube should have been ripped out 30 odd years back, everywhere).
The fact that the 'Cheater plug' is a thing (And that by implication ungrounded outlets have not been ripped out during a routine upgrade in the last 30 odd years exist in enough locations to make selling them at home depot worthwhile).
Clothes driers and similar loads running from two legs of a split phase supply, with the ancillary 120V loads returned to the GROUND pin because neutral was not available, this was broken when it was first done, and should just be illegal.
None of these things would come even close to passing the sniff test in the UK.
Also, what is it with the fondness for overhead distro in cities (It makes sense in low density rural areas), it is visually a mess, prone to pick up any thunderstorm going, and probably materially less reliable then putting it underground (Which I will grant is a higher capital cost option).
All this, and you still cannot get enough juice out of a kitchen socket to boil a kettle in reasonable time (UK kettles are typically 2.5 or 3KW, we likes our tea!).
Regards, Dan.
I guess that goes along with metric conversion in the US
Funny how you present the facts of our electrical distribution system and installations here in general and our operating costs are getting out of control.
Do you have smart meters in the UK? Time of use billing?
What do you use instead of wire nuts? I know the old brass connectors using screws seem to always loosen up when i have to take them apart during any service.
The max we can get out of a kitchen socket is 2.4KW (120Vx20A) using 12awg but usually appliances here never go over 13A or 1560W
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Agreed.
Only on the east coast. West coast uses two bushing trans. edit: oh, and the power company absolutely comes running if you tell em the neutral from the pole is broken and some of the lights in the house fluctuate brighter and some get dimmer.. The major problem is lost neutral.
Aren't we all wire nuts?
There is nothing intrinsically wrong with wire nuts. Application is another story.
That is financial, not electrical. But, basically agree.
Agreed. Except, we can drop 3 prong in where bx is installed. But to require someone to bring in romex after pulling the sheetrock or plaster involves at least two mechanics, and something between 500 and a thousand dollars for an outlet, that's not gonna happen. During a reno, it typically does...just watch HGTV...
As far as I know, 3 wire is illegal.
Don't worry, you'll eventually come around to wire nuts. The NEC is universally adopted around the globe, and they still use em...
The coastal regions have other issues as well. One storm surge would have taken our village's power out for months. Hurricane Sandy was 11 foot over high tide, we had 4 feet of saltwater in the center of our village. At this time, they are considering an independent backup system for emergencies, and some "person" tried to piggyback underground installation of both primary and backup systems for "visual appeal". I went ballistic, it was not pretty. With hundreds of branches underground to buildings, all it takes is one hydraulic break to flood everything and send us back to the stone age. And they had the "bright idea" to put the backup system in the SAME underground setup as the primary!! 12 dozen eggs, one basket.... sheesh.
Well, there's your problem in a nutshell. You're in too much of a hurry. You need to visit this side of the pond, take your shoes off, sit a spell..
The #12 is in the wall. Portable cordage will have higher ampacity because it isn't buried in insulation. Multiconductor ampacity derates at 3 current carrying conductors, and portable cordage from the 3 prong only has two.
Nevermind all the wire and tube..those puppies, man we north americans can push the livin daylights outta single conductors, no derating necessary!!
John
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Thank you very much Zang and all the others that contributed to this topic. The subject of grounding and pretty much everything about diy audio is all very new to me. The rewards are very satisfying and I have had a grin from ear to ear for the last few hours. I built the amp using the chinese Quad 404 clone boards in kit form. I am using a 300va dual 36volt toroidal transformer. I wired it up as per the above image and used the light bulb tester first and was pleased to see the bulb go out without any smoke from the amp. I have listened for a few hours after removing the bulb tester and am very pleased with the result. There is absolutely no audible hum and the sound is good, although I thought it would have a little more bass. I am feeling confident to try my hand at a few gainclones next. Thanks again to all of those who take time out to contribute to this very helpful forum.
Martin
Martin
I would avoid to place the mains socket between the RCA sockets.It would put it at the right side of the case, as well as the trafo and the power supply.
I would move the RCA sockets as well as the amp boards close to each other.
For me, the ideal location of the heatsinks is on the front plate of the case, a la Quad 405.
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