dont suppose you have link to the UK specs please , my quick google could only find lots of "chatter"

 

[PINK]

How is the FE distinguished from other earth connections? What is the definition?

 

How is the FE distinguished from other earth connections? What is the definition?

A functional earth is defined as “Earthing point or points in a system or in an installation or in equipment, for pure poses other than electrical safety, such as the proper functioning of electrical equipment”

. . .but you are still allowed to use pink as a line conductor in control circuits. That doesn’t seem quite right.

 

A functional earth is defined as “Earthing point or points in a system or in an installation or in equipment, for pure poses other than electrical safety, such as the proper functioning of electrical equipment”

. . .but you are still allowed to use pink as a line conductor in control circuits. That doesn’t seem quite right.

That’s what I surmised, which is interesting. So generally what we might call chassis ground or 0V.

Pink? Well, OK, it’s not actually earth. The probably shouldn’t call it that any more than we should call it “ground”. Something like “0V common” or “low common” might work. The adoption of “earth” or “ground” is very misleading.

 

That’s what I surmised, which is interesting. So generally what we might call chassis ground or 0V.

Pink? Well, OK, it’s not actually earth. The probably shouldn’t call it that any more than we should call it “ground”. Something like “0V common” or “low common” might work. The adoption of “earth” or “ground” is very misleading.

That’s what we‘ve always called it. And if a word is defined in any British Standard the definition applies to all British Standards. (And presumably also to CENELEC and IEC standards from which some of them are derived)
It might be interesting to examine how the word “functional” is interpreted in British English and in American English.

 

That’s what we‘ve always called it. And if a word is defined in any British Standard the definition applies to all British Standards. (And presumably also to CENELEC and IEC standards from which some of them are derived)
It might be interesting to examine how the word “functional” is interpreted in British English and in American English.

Well, I understood it properly, your definition confirmed my expectations—but it's the use of earth/ground that I am unhappy with. It obfuscates the nature of the thing being named. It can be understood but it also leads to strange reasoning and confusion if someone isn't aware of where the name breaks down in its analogy.

Just like a(n intentional) "floating ground" makes little actual sense—it's not any kind of "ground", it's an unbonded low side common—using "functional earth" communicates both sensible and senseless parts. The FE may or may not have any connection at all to the earth, I believe the name should reflect that to help newcomers reason properly.

 

Well, I understood it properly, your definition confirmed my expectations—but it's the use of earth/ground that I am unhappy with. It obfuscates the nature of the thing being named. It can be understood but it also leads to strange reasoning and confusion if someone isn't aware of where the name breaks down in its analogy.

Just like a(n intentional) "floating ground" makes little actual sense—it's not any kind of "ground", it's an unbonded low side common—using "functional earth" communicates both sensible and senseless parts. The FE may or may not have any connection at all to the earth, I believe the name should reflect that to help newcomers reason properly.

It’s the thing that the body of your microphone connects to, or the screen of your screened lead. Difficult to think of a better term for it.
[edit] I think “signal earth” is how I would describe it, even though it still contains the word “earth”.

 

It’s the thing that the body of your microphone connects to, or the screen of your screened lead. Difficult to think of a better term for it.
[edit] I think “signal earth” is how I would describe it, even though it still contains the word “earth”.

Well, I think there are two things: first, "screen" or "shield" could have its own color, or just be one of the things that the 0V color refers to. But as I say, "low side common" or "0V common", or something like that would explain it rather than obfuscate it.

I prefer "low side common" because it is only necessarily going to be 0V relative to the high hide of the circuit. My concern with the terminology is like my concern about designing museum exhibits.

One of my rules is "never fake something that you can do for real" (corollary: "if you have to fake something, disclose it and explain why"). The theory behind this rule is that people observe different things, unexpected things, and they reason based on observation. You can never know how perceptive the viewer is, so if you fake something they may attempt to reconcile the faked behavior with their other observations, however cleverly, and very soon they will be completely off the path.

Naming things is very important. And they shouldn't be named in way that is only useful to people "in the know". Names should allow as much independent inference about the named thing as is practical. A naive person shouldn't be mislead by a name, particularly when it is potentially a safety issue, as "earth" can be.

This may seem picky, and I suppose it is, but part of my career(s) was focusing on this level of design—for devices, programs (function and variable names), and memetic systems (project management, process, &c) it was my method to focus on naming much more than most. The result was a demonstrably better result in many dimensions. Good names provide "handles" that allow apprehension of the many aspects of the named thing.

Hmm... OK, the horse seems to be dead...

 

A microphone cable shield is a "signal common" even when not connected to the chassis or whatever.

But as for the pink "functional ground, the NEC is rather specific in that no part of the safety grounding system is to carry any operating current. That is very clear. So the "functional ground" should be green with a pink stripe.

BUT since the green wire connection is part of the functional system it needs to be a separate run to wherever that solid "ground" point is.

Now I am trying to think of what such a system might be. What comes to mind is the G.M. "Ground Detect"indicators, which were mandated on electrical enclosure doors in some G.M. plants. They were across the isolated 120 volts system with the connection between tied to the equipment frame. Connecting either side of the isolated system to chassis will extinguish one lite and the other will be full brilliance.

 

Well, I think there are two things: first, "screen" or "shield" could have its own color, or just be one of the things that the 0V color refers to. But as I say, "low side common" or "0V common", or something like that would explain it rather than obfuscate it.

I prefer "low side common" because it is only necessarily going to be 0V relative to the high hide of the circuit. My concern with the terminology is like my concern about designing museum exhibits.

One of my rules is "never fake something that you can do for real" (corollary: "if you have to fake something, disclose it and explain why"). The theory behind this rule is that people observe different things, unexpected things, and they reason based on observation. You can never know how perceptive the viewer is, so if you fake something they may attempt to reconcile the faked behavior with their other observations, however cleverly, and very soon they will be completely off the path.

Naming things is very important. And they shouldn't be named in way that is only useful to people "in the know". Names should allow as much independent inference about the named thing as is practical. A naive person shouldn't be mislead by a name, particularly when it is potentially a safety issue, as "earth" can be.

This may seem picky, and I suppose it is, but part of my career(s) was focusing on this level of design—for devices, programs (function and variable names), and memetic systems (project management, process, &c) it was my method to focus on naming much more than most. The result was a demonstrably better result in many dimensions. Good names provide "handles" that allow apprehension of the many aspects of the named thing.

Hmm... OK, the horse seems to be dead...

If we all did that, I’d actually be able to understand the error messages from my microcontroller development software, and a computer program that fetches and displays html files wouldn‘t be known by a word describing the feeding habits of goats.
But seriously, the functional earth (microphone bodies etc) is usually connected to earth, but just not with the gauge of cable that would take a live-to-earth short for long enough to clear the fuse.

 

If we all did that, I’d actually be able to understand the error messages from my microcontroller development software, and a computer program that fetches and displays html files wouldn‘t be known by a word describing the feeding habits of goats.
But seriously, the functional earth (microphone bodies etc) is usually connected to earth, but just not with the gauge of cable that would take a live-to-earth short for long enough to clear the fuse.

Yes, they are sometimes connected to earth but I guess I would prefer to see something like pink for low side common and pink with green for bonded low side common. The pink is dominant since it is not a safety ground but the green is present to show it is not isolated from ground.

I know that I have a particular focus on this stuff, and perhaps it is not well scaled, but my perspective makes it look very large on the list of things that should be done. And like all things that "should be" it as a moral note to it that I recognize seems to be more than it deserves. It's a quirk. At least I am self-aware and don't imagine it is an objective fact.

 

(Sort of off topic)
I have an interesting tale about band members on a nylon carpet complaining that the amplifier system was not properly grounded because they were getting shocks off of the microphones. I suggested that they do one practice in stocking feet, they refused and said I was stupid. So the microphone stands were connected and grounded with some automotive jump-start cable, tied to a copper heating radiator pipe. The shocks continued because "the amplifier was not properly grounded." So I removed the jumper cables and before the next performance, sprayed a lot of water on the carpet. About a pint for an 8 by 5 carpet. It as wet. No shocks.. I never did explain what I did for that group.

 

RE: nsaspook <<I wish there was an internal standard for wiring colors>>
I wish there was a death penalty for producers using red for minus and blue for plus. Instantly life would become better for 5%.

 

The problem I had when I came to N.A. was where the term 'Ground' is used for 'common' in general, whether connected to earth ground or not.
As Dr Archambeault succinctly put it. Too ambiguous!
(Even the earth symbol itself is widely misused, repeatedly).

 

Yes, they are sometimes connected to earth but I guess I would prefer to see something like pink for low side common and pink with green for bonded low side common. The pink is dominant since it is not a safety ground but the green is present to show it is not isolated from ground.

I know that I have a particular focus on this stuff, and perhaps it is not well scaled, but my perspective makes it look very large on the list of things that should be done. And like all things that "should be" it as a moral note to it that I recognize seems to be more than it deserves. It's a quirk. At least I am self-aware and don't imagine it is an objective fact.

I never gave something as prosaic as earthing a second thought until I started working in off-grid power. Now I find it quite fascinating (there aren't any trains to spot around here).
The impedance of an earthing rod is required to be <200Ω, that's nowhere near low enough for the fault current to clear a protection device. It's the equipotential bonding that sees to that. So perhaps the functional earth is the usual situation, where the ground potential serves as a reference, and its the safety earthing that is the "unusual" application for the connection to ground.

 

That is why at one company the term was "star point"as in "commoned" Star Point. Rather redundant, that, but fairly clear.
Red as negative comes from the phone system for reasons never clear to me. Not sure why it is, except in the RETMA color code red=2 while green =5. But phone wiring is different from power wiring and the two should never ever mix..

It is never clear as to the benefit, safety or otherwise, of connecting the frame of an isolated engine powered generator to a stake driven into the ground, other than to provide a shock hazard from half of the wires connected to it. It must be an emotional feeling of safety, I suspect.

 

RE: nsaspook <<I wish there was an internal standard for wiring colors>>
I wish there was a death penalty for producers using red for minus and blue for plus. Instantly life would become better for 5%.

Beware the figure of 8 cable with black tracer.
Some people believe that the tracer indicates the positive conductor, regardless of the colour of the tracer.
Some people believe that the tracer indicates the negative conductor, regardless of the colour of the tracer.
Some people believe that the black tracer indicates the negative. If the tracer were red, then some people would believe it to be the positive.

 

I believe in those instances that I must grab my meter and check. I have seen too much work by those who do not regard insulation color as important. Certainly it is inconvenient, certainly it avoids nasty goofs.. It does slow things a bit but not as much as destroying hardware that might be expensive.