Finally stop quoting your 4mm and 5mm mantra as the only safety metric,
Gyro, you must learn to READ.
I have never claimed 4 and 5mm as the only safety metric. I have always mentioned that the environment must be considered.
Already in my first post I wrote:
"This is a stereo. It's meant for a normal domestic environment, i.e. no excessive humidity or dust. It is not ment to be mechanically abused as power tools are."
I have also written:
"The intended use and environment plays a big role in the design and certification process. Equipment meant to be used in a normal office / living room environment is subject to lighter regulations than something meant for use in the kitchen or outdoors or as toys for instance."
But you prefer to be blind for this. Only you can tell why.
Electrical safety has nothing to do with words written on a paper.
Legal safety has something to do with words on paper.
No product will become safe because of words, and no product will become unsafe because we call the product something else.
What makes a product safe depends on the environment and physics. 4 and 5mm will provide the clearances necessary for normal mains voltages in a normal office or living room environment, regardless of what is written on any paper or what we prefer to call the product.
The reason the standards increases this distances for certain products is not because we call the product someting else than computer or fax or monitor. The reason they demand more clearance for some products is because they know that those products probably will be exposed to a more demanding environment, for instance people acting stupid. They increase the safety margin. Not necessarily because the product itself needs it, but because of the expected environment. They don't make a separate standard for every product imaginable. They try to group them according to expected use and environment.
Your computer monitor with 4/5mm distances is considered perfectly safe when you use it as a monitor for your computer in your living room. This monitor will not become unsafe just because you hang it on the wall in the same living room and uses it as a TV together with a TV dongle. According to words written on paper, it is now a TV and should be tested as a TV to be conform with a more demanding standard. Because of this it is legally unsafe. It is still electrically safe because it is still used in the environment it was designed for. If you move it to the kitchen or outdoors, you can find it to be both electricall and legally unsafe because the environment is too different from what it was designed for regardless of being used as a TV or a monitor.
But - I don't think you ever will get it.
It seems like it is impossible for you to see the difference between how to find out if an existing product can be considered as safe to use, and the design process needed to create a new product that will have to follow all legal requirement in today's legislation.
Sigh, ok you've provoked me into final comments 
1. I could go on at length about degree of contamination - often old consumer equipment is very dusty inside, in a smoker's home MUCH worse.
2. As Hero999 states, the mains supply is subject to transients. Scores of pages are spent in the Test equipment section on the safety of DMMs which might very occasionally be connected to the mains by unwise people. Most of those have creepage and clearances greater than 4/5mm but they lack the additional surge withstanding components to withstand possible transients. AV equipment is normally permanently plugged into the mains.
I could go on but since you have chosen to differentiate your definition of electrical safety from the Legal definition of safety.... and since this is the BEGINNERS section of the forum...
Which definition of safety will an Insurance Company or Court base it's judgement on in case of death or injury through Electrocution or Fire? The LEGAL definition of safety or the trondeTM definition of safety?
You don't get it Gyro, You really don't get it. You don't want to understand what I say, and you do whatever you can to twist it as much as possible. Only you can tell why.
I HAVE been very specific about the prerequisite for when we can use the 4/5mm as a
guide when we
evaluate the risk for danger.
I HAVE been very specific about the impact the environment will have on safety. I even gave an example for how small changes can change everything.
I have NEVER claimed that these distances can be used as a guideline for new producs.
I have used them as an EXAMPLE for why normal mains voltages are usually not extremely dangerous as many seems to believe.
No need to tell me about contamination. I made a living out of repairing TVs long time ago. Heavy smokers without knowledge of vacuum cleaners are no strangers to me. But, I do really think I mentioned dustfree environment as a prerequisite, didn't I? Yes, I do really think I did so. Don't know why you bring it up again.
When it comes to transients: Yes, they exist. They have even considered them when they made the standards. The funny thing is that both office equipment and AV-equipment is meant to be used in the same category-II overvoltage environment. That is what you have in an office or a normal home, so the transients will be the same. Both types of equipment are usually permanently connected to mains as well. I guess you are aware of this?
The real difference between those two types of equipment, is the environment. This is why they increased the safety margins on AV-equipment. This is not the same as office equipment, or anything following that standard, is close to unsafe when used in the
intended environment. I have said it several times, but again, you prefer to twist it as much as possible.
*
This is about Europe, but it seems like most countries follow this route when they upgrade their laws.
In Europe, safety for most electrical equipment is regulated by the Low Voltage Directive. The LVD is "the law" about this here.
The LVD says very little about specific technical things. The LVD is based on "function" instead of details. The LVD lists some "functions" that are vital for a product. Most important is (in free wording) "not cause damage to any person", "not cause any damage to animals" and "not cause any damage to buildings". Then, they say, it's up to you to figure out how to give these "functions" to your product.
They know this can be difficult, so they reach out an helping hand. They tell you that if you build your product in accordance to what is known as "harmonised standards" (those with a name beginning with EN), you will most likely get it right, and be OK.
If you want to sell in the EU, you must prove that your product is safe. That is why you must sign a "declaration of conformity."
When you sign this declaration, you don't sign for being compliant with a standard, as many believe. You sign for being compliant with the LVD.
The funny thing about this, is that it is usually possible to be legally in compliance with a directive
without any relation between the product and any standard.
When you sign this "declaration of conformity" you must also tell why you think you are OK. This is why you will have to list the relavant standards you have used. But, it is possible to skip standards in most instances. Then you must prove your product is safe in another way. It is sometimes done, but mostly for other directives than the LVD becaude of the cost and difficulties involved.
Because the LVD is based on "function", it is sometimes possible to "cherry-pick" standards without being caught for wrong-doing. They do so on AV-equipment and office equipment for instance.
I have got some spoken info on parts of the upcoming combined standard for AV and office equipment. It is not the final version, so it can be something different in the final version. I was told that they have shaved off 1 mm on each of the 4 / 5 mm distances that has created so much noise...
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