Why is PC chasis put on voltage when earth/ground wire is missing ?!?

[Chieftain of the Carpet Crawlers]

Almost all portable PCs use two pin mains adapters as an external brick,

You lose. SkyTard's PC is a metal case Chassis PC, and the ATX spec
has NO two pin AC feeds.

Portable PCs are NOT "AC powered". Their dongles are. You lose twice.

 

[[email protected]]

Almost all portable PCs use two pin mains adapters as an external brick,

Really ?

I have seen quite a lot using the 2 pole IEC 60320-1 C1/C7 as well as
the 3 pole C5 variant.

and there is no reason why some of the micro PCs can't do it that way
either.

Desktops usually use cheap and nasty high power switching supplies in a
metal chassis case which any sensible person would earth.

At least in Europe, previously it has been completely legal to install
two pole (Class 0) sockets into a dry environment such as normal
living rooms, however, kitchens and bathrooms require Class 1 grounded
3 pole sockets.

Mains plugs can be Class 0 (L+N) that can be plugged into any Class 0
socket in a dry environment.

A Class 1 (L+N+PE) plug will fit into any Class 0 or Class I socket
and hence is a legal combination. A doubly insulated device (two
squares inside each other) can be mechanically plugged into any
socket.

A class 0 plug does not fit into a class 1 socket, thus, it is illegal
to use a Class 0 device in some wet environment.

 

[Martin Brown]

Really ?

I have seen quite a lot using the 2 pole IEC 60320-1 C1/C7 as well as
the 3 pole C5 variant.

I think you are agreeing with me here. I have one Liteon PSU for a
portable that has a 3 pole C5 flex and all the rest are two pole C7.

In the UK the mains plug has to be 3 pin with live fused since you
cannot plug it into the wall without first inserting the longer earth
pin to release the gate in the socket that hides live and neutral.

At least in Europe, previously it has been completely legal to install
two pole (Class 0) sockets into a dry environment such as normal
living rooms, however, kitchens and bathrooms require Class 1 grounded
3 pole sockets.

In mainland Europe yes although most wall sockets where I have lived and
worked in Belgium were 3 pin (though compact adaptors to Class 0 were
commonly used - sometimes for appliances that should be earthed).

Mains plugs can be Class 0 (L+N) that can be plugged into any Class 0
socket in a dry environment.

A Class 1 (L+N+PE) plug will fit into any Class 0 or Class I socket
and hence is a legal combination. A doubly insulated device (two
squares inside each other) can be mechanically plugged into any
socket.

A class 0 plug does not fit into a class 1 socket, thus, it is illegal
to use a Class 0 device in some wet environment.

In the UK electric code mains sockets in the bathroom are forbidden and
any switches must be on the ceiling with a pull cord.

Only an isolated shaver adaptor is permitted and is subject to
restrictions on its position. Too many people were killed in the past by
electric fires falling into baths in the days before ELCBs.

http://en.wikipedia.org/wiki/Electrical_wiring_in_the_United_Kingdom#Bathrooms

The UK electrical wiring standards have been degraded recently to match
EEC regulations and facilitate increased deaths in bathrooms.

Regards,
Martin Brown

 

[tuinkabouter]

Op 5/17/2011 1:42 AM, Bob F schreef:

In the US, residential power is typically 240 Volt AC. That is through two
wires, and is two sine waves (look it up) 180 degrees out of phase.
Additionally, there is a groundwire that is grounded where it comes into your
house. The two power "phases" are 180 degrees out of phase with each other. When
one reaches +120V, the other reaches -120V. Thus, the voltage difference between
them is 240VAC (volts alternating current) "peak to peak".

240 is only the effective value. peak to peak value is higher.

 

[Jeroen]

Hi,

Can it not simply dump the excessive fluctuations to the other wire ?

Because the CISPR 22 standard for conducted emission prescribes
only the limits for the current that flows into the live and
neutral wires, but not the ground wire. So the ground wire is
fair game. The Y capacitors in the EMI filter will dump the RF
EMI current into the ground lead, where it will not be measured
for the EMI approbation.

The effect of the Y capacitors on the voltage of the cabinet when
the ground is not actually connected has already been explained
to you. It's still safe, it may even comply with "class II" safety
rules, but it is unpleasant. Just use the damn ground then !

PS for optimum results sometimes this means that (part of) the
EMI filter must be placed in the mains plug, which becomes *fat*.
With only an EMI filter on the other side of the mains lead there
may be some crosstalk from the dirty ground wire into the clean
live and neutral wires, making them dirty again. So they must be
cleaned up again in or near the mains plug.

All this is really a dirty technicality. The reason for limiting
conducted emission is because it correlates well with the
radiated emission (they are both part of the same current loop),
so if you limit one then you have automatically limited the
other too. Except when you allow not to measure one wire.....

-- J.

 

[I AM THAT I AM]

"Skybuck Flying" schreef in bericht

Antec 1200 case does not mention it as well:

http://www.antec.com/pdf/manuals/1200_EN manual.pdf




Off course it is Not in the manual because there is no power supply in it
when you buy it!!!!!

He is as dumb as it gets. Hands down.

 

[Skybuck Flying]

"Skybuck Flying" schreef in bericht

Antec 1200 case does not mention it as well:

http://www.antec.com/pdf/manuals/1200_EN manual.pdf




Off course it is Not in the manual because there is no power supply in it
when you buy it!!!!!

How the fok does the voltage get on the chasis ?!?!

Bye,
Skybuck.

 

[Shaun]

"Hal" wrote in message

Knip----

Seasonic S12 600 watt manual:

http://www.seasonicusa.com/images/BrochureManuals/NewS12Manual1.pdf


Why does it need to be earthed ? Why does it need a third earth wire ?

Why cannot it not simply use two wires without earth and without putting
the chasis under voltage ?!?

Why does it need to put the chasis under voltage when it's not earthed ?

You have not answered any of my questions and seem to think that these
questions are documented somewhere which so far appears not to be the
case.

Bye,
Skybuck.

You need an EMI expert to answer this question. But I am shure that if there
are ways, they will be (much) more costly then the presently choosen
solution. So the second question is: "Are most customers willing to pay
extra for something, almost nobody (except you) is intersted in."

Hal


SkyTard Masturbating, You are such a fucking idiot!!!

The people that posted did answer your questions, you just to stupid to
realize it.



There are four ways that you can get voltage and current on the chassis.

1. The input filter capacitors on both and Hot and Neutral lines coming in
connect to chassis ground. This is so that capacitors remove most of the
electrical noise that is entering the PSU.

2. Leakage current caused by parasitic capacitance. Any conductor or
component inside the power supply will have a very small amount of
capacitance to the chassis, case of the power supply. The capacitance
causes a small amount of current to flow through the chassis to ground.

3. Induction. There are coils and transformers and wires all carrying
current, when there is current there is a magnetic field. Some of the field
is outside the coil or transformer and it will induce a current in the
chassis.

4. A major electrical fault where a bare part of a wire touches the power
supply case or a component comes partially loose and touches the case. This
will usually result in popping a fuse or breaker, which is by design. This
is what the ground wire is mostly for. You don't want 120 or 240 volts on
the chassis. In both of these cases the power supply should not be working
anymore either.


Shaun

 

[Shaun]

"Shaun" wrote in message


"Hal" wrote in message

Knip----

Seasonic S12 600 watt manual:

http://www.seasonicusa.com/images/BrochureManuals/NewS12Manual1.pdf


Why does it need to be earthed ? Why does it need a third earth wire ?

Why cannot it not simply use two wires without earth and without putting
the chasis under voltage ?!?

Why does it need to put the chasis under voltage when it's not earthed ?

You have not answered any of my questions and seem to think that these
questions are documented somewhere which so far appears not to be the
case.

Bye,
Skybuck.

You need an EMI expert to answer this question. But I am shure that if there
are ways, they will be (much) more costly then the presently choosen
solution. So the second question is: "Are most customers willing to pay
extra for something, almost nobody (except you) is intersted in."

Hal


SkyTard Masturbating, You are such a fucking idiot!!!

The people that posted did answer your questions, you just to stupid to
realize it.



There are four ways that you can get voltage and current on the chassis.

1. The input filter capacitors on both and Hot and Neutral lines coming in
connect to chassis ground. This is so that capacitors remove most of the
electrical noise that is entering the PSU.

2. Leakage current caused by parasitic capacitance. Any conductor or
component inside the power supply will have a very small amount of
capacitance to the chassis, case of the power supply. The capacitance
causes a small amount of current to flow through the chassis to ground.

3. Induction. There are coils and transformers and wires all carrying
current, when there is current there is a magnetic field. Some of the field
is outside the coil or transformer and it will induce a current in the
chassis.

4. A major electrical fault where a bare part of a wire touches the power
supply case or a component comes partially loose and touches the case, or an
electronic component shorts out or fails. This
will usually result in popping a fuse or breaker, which is by design. This
is what the ground wire is mostly for. You don't want 120 or 240 volts on
the chassis. In these cases the power supply should not be working
anymore either.

The ground wire is there for your safety. I a major fault occurs inside the
PSU, it will usually trip a fuse or breaker to protect you from electric
shock. To get an electric shock you have to touch something live and
something grounded at the same time. The design of electrical equipment
follows UL specifications and it is designed to reduce electrical shocks
from equipment.

If you aren't using a ground to plug in you PC and you touch the case and
something grounded, you'll probably be ok and won't even notice it, but if
there is a component fault inside the power supply then you could get a
shock. If a major fault occurs in the power supply and the fuse / breaker
doesn't trip for some reason and you touch it and something ground you will
get a major shock. If you are in very poor health and using an ungrounded
device and a connection was made to you on or near a cut or incision and
another part of you touched ground, it can kill you.


Shaun