Tingles from DVD players

"Russ_Verdon"

** Yes - the units are not longer "double insulated" or of "class 2" construction if you substitute a 3 core lead. ** Only a few folk feel any tingle at all. ** Completely silly.

The use of Class 2 construction is a VERY deliberate decision and for very good reasons.

** Absolute crapology.

** You seriously temp me.

Never heard of earth loop hum ?????

......... Phil

Sure, that seems obvious. The device would then be modified, the original electrical approval would not be valid, and it would not be possible to approve the device as a class 2 device with the case earthed. Are you aware of any technical reason why the device could not be approved as a class 1 device (hypothetically, since the cost of testing would be more than prohibitive)? To the best of my knowledge the insulation requirements of a class 2 device are more strict than would be required for a class 1 device, though I don't know if there are any fusing requirements for class

1 which would not have applied to the class 2 device when it was built.

Apart from the earth loop hum you refer to, what reasons are you referring to?

Chris

** You have completely missed the point.

** Correct - so the markings on the unit (ie "class 2" and the double square symbols) would be then ILLEGAL. ** Yawn.

This is an entirely separate issue to the OP's question AND my reply.

** 1. Class 2 construction is far SAFER for the user.

1. Class 2 construction meets world wide electrical approvals making it far easier for makers to market the same design world wide.

2. The use of class 2 is almost universal for some classes of electronic equipment.

1. There is a PROHIBITION on interconnecting class 1 and class 2 equipment.

........ Phil

like a laplink cable?

Bye. Jasen

"Jasen Betts"

** Piss off - kiwi tenth wit.

The sheep are missing you.

....... Phil

Ok but I was interested, in case you know something about it that I could learn from. I agree that I am slightly changing the subject, however I thought it worth asking since the OP or others in a similar position might be inclined to do whatever they feel like, provided they think it is safe, but in spite of the law. If there were a serious technical reason why it would be unsafe, rather than a (re)labelling or legal issue then it would be good to be aware of it.

I am surprised by (4) since many hi-fi amplifiers (at least older ones) do have an earthed case, for better or for worse. It is not made very clear to the average user that connecting the amplifier to a typical (class 2) CD player would be prohibited, for example I haven't seen such a warning in the instruction manual of a CD player. I don't have the necessary knowledge of the standards to refute what you say, but it does surprise me. Perhaps you mean something different when you say 'interconnecting' from what I had interpreted, i.e. connecting a shielded audio cable between two devices, thus connecting their metal cases together. Anyway thanks for your answer.

Chris

"Chris Jones"

** Do you constantly move the goalposts at sporting events too ?

.......... Phil

** Have you never seen the words " Double Insulated - Do Not Earth " on the back of a class 2 item ??

Pretty clear isn't it?

** It is not prohibited by criminal law - so no police officer will arrest you for doing it.

But it is an * unsafe practice* that could be considered as " serious negligence " by a court if a person were injured or killed.

** " Double Insulated - Do Not Earth " on the back of the player is a *stronger warning* that anything printed in a user manual that likely gets lost with the packaging.

Equipment makers are not liable for what users may WRONGLY do when interconnecting items of gear - so just ignore the issue.

The matter is very much an *X rated topic * in the home entertainment electronics industry.

** Imagine a hi-fi system with every item in it class 2 - so there is no AC ground to the metalwork.

Next, an item is added to the system, ie a nice old valve tuner just bought from Ebay but with no AC plug.

Next, the user inadvertently wires up the new plug wrongly with active and earth reversed and makes all the connections.

The hi-fi system will still work just as before ( but not the tuner) but with ALL the metalwork, connecting leads and even the loud speakers now LIVE !!!

In countries with 240 volt AC power, this is a FATAL accident scenario !!!!

NOTE:

One of the BIGGEST user safety advantages of class 2 construction is that no matter how WRONGLY the AC plug is wired & no matter what is wrong with the AC outlet, you cannot get active onto the earth of the gear.

........ Phil

a major advantage of class 2 is that its cheaper. the plug, cable and interconnects cost less, and because of the double insulation, none of the metalwork has to be earthed, which it does with class 1 - for many standards the metalwork earthing must carry the rated current, further increasing the cost.

The above scenario can only happen when people fiddle with things, and so is not relevant to manufacturers (they build them right). Such a scenario also occurs with a single class 1 appliance wired up by the same d*****ad. Voila, live chassis (and dead operator).

Cheers Terry

"Terry Given"

** Bullshit it is.

The specs for the AC supply transformer alone are way beyond that for class

2. The design rules for every part of the AC side are way tougher.

** By a few cents only.

** What absolute drivel. ** More " Pinball Wizard " bullshit. ** It is *very elevata" to the increased safety of class 2.

It is *very relevant" to the PROHIBITION on earthing a class 2 appliance.

** But NOT a system of interconnected class 1 appliances.

Hence the prohibition on earthing a class 2 appliance or system thereof.

They are very safe until you do that.

** Please go try it now.

....... Phil

double insulation pretty much means 2 sets of insulation, so that when one fails there is still one left. yes the xfmr is a bit more expensive, but a whole bunch of other stuff gets cheaper.

look inside a hair dryer, that is far, far cheaper as a class 2 device than class 1.

not really, and they are made easier by the proliferation of plastic.

why do you think they use phenolic paper PCBs, and an interseting mix of

1%, 5%, 10% and 20% components? when you build 500,000,000 of something, all them cents add up.

Phil has obviously never read BS-EN61010

depends on the system, and how they are interconnected.

Cheers Terry

"The Pinball Wizard of Nelson "

** Absolute bullshit. ** Absolute bullshit.

** Much more - the cheapest construction methods are outlawed.

The popular and cheap toroidal is basically outlawed.

** Absolute bullshit.

** The subject is DVD players and the like - f*****ad.

** Get stuffed - Kiwi LIAR !!

....... Phil

ROTFLMAO! You are demonstrably wrong, viz.:

first, lets un-snip what I posted:

"double insulation pretty much means 2 sets of insulation, so that when one fails there is still one left"

AS/NZS3000:2000 Wiring Rules states:

1.4.26 Class II equipment - Equipment in which protection against electric shock does not rely on basic insulation only, but in which additional safety precautions such as double insulation or reinforced insulation are provided, there being no provision for protective earthing or reliance upon installation conditions

1.4.57 Insulation System One, or a combination of, the following: (a) Basic Insulation - the insulation applied to live parts, to provide basic protection against electric shock (b) Supplementary Insulation - an independant insulation applied in addition to basic insulation in order to ensure protection against electric shock in the event of a failure of the Basic Insulation (c) Double Insulation - insulation comprising both Basic Insulation and Supplementary Insulation

In other words, exactly what I said.

Bwahahahahaha!

pah. look at those sorts of xfmrs, its not very complex. split bobbins with lids basically, and a bit more creepage/clearance. they still wind them with magnet wire; I've yet to see a consumer xfmr wound with Furukawa Tex-E or any other form of triple-insulated wire....

on what basis?

and toroids are not that cheap to wind c.f. an e-core bobbin, especially the little ones (and the big ones)

Cheers Terry

I've just checked all the double insulated items in my home and NONE of them carry a warning such as you describe. It would be useful to know how general such a warning is. I suggest everyone reading this thread check their equipment and report back their findings. My equipment includes items from NEC, Philips, Sony, Teac, Mitsubishi, Sanyo & Microsoft.

snip

So where does the "PROHIBITION" come from? Previously you said such interconnection was prohibited, now you're saying to ignore the issue??

If this danger was significant then the use of Class 2 equipment is inherently unsafe because it would be relying on user action to make it safe, the user action being to not interconnect with other commonly available items. As you say above, "Equipment makers are not liable for what users may WRONGLY do.....", but regulators are always interested in such things. They seem relaxed about the situation.

snip

-- Regards Malcolm Remove sharp objects to get a valid e-mail address

I don't consider posting to usenet to be a competition, though you are free to consider it whatever you want. I just like to learn stuff.

Chris

Ok, I can see that wiring the plug of the class 1 device wrongly has made the class 1 device as well as the class 2 device dangerous to touch. I think that the user was pretty much asking for a jolt whether or not the class 2 device was connected (or even existed at all), but in principle I see why the manufacturer of the class 2 device would not want the two devices interconnected, so the user gets electrocuted whilst touching the device made by someone else, that would be cheaper in court....

The root cause of the problem is of course having someone who thinks they can wire a plug but cannot. The problem is they might not be the one to get killed, it'll be the neighbour's kid or something like that.

Thanks, that's the first "class 2 is safer" argument that makes sense to me. In the context of incompetent and/or amateur electricians, no ELCB, and no regular testing of power socket wiring and portable appliance testing, I can see that advantage of class 2. Those conditions are probably fairly common too.

Chris

"Chris Jones"

** Then why keep moving the goal posts like is is one you cannot bear to loose ?? ** If you mean that, then why make it impossible for anyone to answer you ?

........ Phil

"Malcolm Moore" "Phil Allison"

** The warning notice is not compulsory.

Only the use of the "double square" symbol or the words "Double Insulated" are.

** The fact that a class 2 appliance must not be earthed. ** Huh ???

What madman's logic is this ?

What the hell do you think "X -rated " means ???

** Absolute drivel.

Class 2 construction appliances are inherently much safer than class 1 types.

What users do that COMPROMISES that additional safety is beyond the control of makers or authorities.

** SFA they can do about it.

The issue is one of legal liability on the part of someone who elects to earth a class 2 item.

........ Phil

"Chris Jones"

** Not just one device, but an entire hi-fi system INCLUDING the damn speakers !!! ** A third party could be the one electrocuted - maybe a small child. ** The makers of the class 2 devices are not liable in such a case.

Their items are not permitted to be connected to the earth system of another.

** Millions of them around.

Heaps of places sell 3 pin plugs to the public.

** The punishment for mis-wiring a plug ought not be the death of anyone. ** The most common cause of electrocution in the home is ( or was until recently) incorrectly wired plugs and extension leads.

The worst electrocution trap in where BOTH miswired but BOTH work OK unless the two meet up.

1. The extension lead has active and neutral wires reversed, earth is wired OK ( most consider this to be harmless).
2. The appliance has earth and neutral wires reversed, active is on the correct pin ( appliance works fine in normal outlet).

When appliance "2" meets lead " 1" ?????

Death to a toddler.

....... Phil