On Dec 15, 6:37*pm, mike wrote:
lsmartino wrote:
On 12 dic, 23:51, mike wrote:
Phil Allison wrote:
"mike"
Ok, but how did it make it past the "fire hazard" category.
** The design of the transformer prevents any fire or electrocution hazard.
It's surely a source of ignition when you knock it over onto
a pair of scissors on the desk.
** *Shorting the secondary winding is one of the tests carried out when
certifying a transformer as "class 2" or double insulated. The unit must not
overheat or burn to the extent that primary and secondary circuits can
become fused.
Most often this is achieved by adding a thermal fuse to the primary circuit
that will open if the winding temp reaches a point that could damage the
insulation used to make the tranny - * about 120C in most examples.
Some older designs used fireproof insulation between the primary and
secondary and the winding were contained on separate halves of a plastic
bobbin. Such a tranny could smoke and burn but still not present an
electrocution hazard.
.... *Phil
Ok, but what about the spark that happens when you knock it over
while refilling your butane torch? *Or when you just cleaned a part
with alcohol. *Dumb design!!!
Safety design is a LOT more than just the obvious.
There'd be a lot fewer houses burned to the ground if only engineers
thought more about how their products are used and the hazards
caused by confluence of circumstance.
Did I mention...DUMB DESIGN!!

But you bought a chinese no name "design" lamp, with chinese
construction "quality" and chinese design "aspect" and you pretend
that this lamp should be properly designed??? I bet you that the
creator of that "jewel" isn t even an engineer.

If you don t fell comfortable with the lamp, and I wouldn t BTW, just
trash it.

Well...
I didn't buy it.
The issue is not about the buyer's ability to determine the safety
of a Chinese lamp.
The issue is about the certification agencies who have the device in their
lab for qualification.
Their JOB is to protect me from harm.
They should not have qualified such a device.
You may feel otherwise, that's your right.- Hide quoted text -

- Show quoted text -

Take into account the fact that fake electrical chinese products
almost always have fake certification labels. I have seen countless of
useless power strip with fake UL labels, or badly constructed computer
cases with a fake CE seal stamped over the chassis. I have seen even
fake circuit breakers made in China with UL marks, so don´t assume
that a poor quality electrical chinese product has been properly
inspected just because it bears a UL or CE label.

On Dec 15, 6:52*pm, mike wrote:
William Sommerwerck wrote:
As to the risk here, I routinely touch both clips of the 1-amp 12 volt
battery charger I have. I havent' done that with the 8 amp charger,
probably because the phrase "8 amp" scares me, but it shoudln't
and tomorrow I will, *I'll even find some alcohol to spark in. *If I
don't
post back, it means my house burned down and took my computer
and me with it.

It only takes a few milliamps to kill you. Assuming the current
has a path to a vital organ, like the heart.

It takes about 100mA through the heart to kill you.

Guys, a battery charger is not a constant-current device! It provides only
the current determined by its charging voltage (which I assume starts at
around 14V) and your skin resistance, which even when your hands are wet, is
no lower than a few thousand ohms.

YOU CANNOT BE ELCTROCUTED BY THE OUTPUT OF A CAR-BATTERY CHARGER.

That statement suggests a misguided interpretation of "certainty".
I doubt you've considered ALL possibilities.
"unlikely" might be a better word than "cannot" for use in that
sentence.- Hide quoted text -

- Show quoted text -

Can you illustrate a real life situation where a 12V battery
electrocutes a human being? I posted a skin resistance table that
makes that possibility higly unlikely.

On Wed, 15 Dec 2010 05:52:33 -0800, the renowned "William Sommerwerck"
wrote:

As to the risk here, I routinely touch both clips of the 1-amp 12 volt
battery charger I have. I havent' done that with the 8 amp charger,
probably because the phrase "8 amp" scares me, but it shoudln't
and tomorrow I will, I'll even find some alcohol to spark in. If I
don't
post back, it means my house burned down and took my computer
and me with it.

It only takes a few milliamps to kill you. Assuming the current
has a path to a vital organ, like the heart.

It takes about 100mA through the heart to kill you.

Guys, a battery charger is not a constant-current device! It provides only
the current determined by its charging voltage (which I assume starts at
around 14V) and your skin resistance, which even when your hands are wet, is
no lower than a few thousand ohms.

YOU CANNOT BE ELCTROCUTED BY THE OUTPUT OF A CAR-BATTERY CHARGER.


Unless it is defective.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Maybe you're not familiar with the expression.. Never Say Never.

Being a repair newsgroup, many folks have likely encountered damaged battery
chargers, and not knowing every possible fault, including improper previous
repairs, one never knows if an electrical device has a fatal fault or not
until it's been examined and tested.

Nearly every electronic equipment service manual printed in the last 40
years (at least), includes a method to test line operated equipment for
hazardous leakage levels that can be fatal.
Safe levels of leakage for line operated equipment fall within the uA
microamp range.. that's Less than a mA milliamp.

I believe that actual current threshold determined to be hazardous is about
35mA, across the heart, which can interrupt normal heart rythyms.

So, with a small voltage applied to fingers of one hand with the other hand
grounded, the additional skin resistance of the arms will decrease the
possibility of a fatal shock.
That same voltage, applied to points near the heart will increase the
possibility of a fatal shock.

By following standard safe practices, one can be confident that they are
working safely.. one hand in pocket, standing on dry, insulated material,
good lighting, concentrating on what you're doing with no distractions or
practical jokers around.. and one of my own personal habits which is to not
have anyone standing behind you. You can't see or predict that person's
movements, so tell 'em to move where you can see them.

FWIW, a number of years ago there was a safety recall of some Dewalt
cordless power tool battery chargers (not a car battery charger), because
one of the battery terminals was not isolated from the AC line (by poor
design).
That model definitely presented a deadly fault, so don't always expect that
new items are perfectly safe, either.

--
Cheers,
WB
..............


"William Sommerwerck" wrote in message
...

It takes about 100mA through the heart to kill you.

Guys, a battery charger is not a constant-current device! It provides only
the current determined by its charging voltage (which I assume starts at
around 14V) and your skin resistance, which even when your hands are wet,
is
no lower than a few thousand ohms.

YOU CANNOT BE ELCTROCUTED BY THE OUTPUT OF A CAR-BATTERY CHARGER.

Maybe you're not familiar with the expression.. Never Say Never.

We were not talking about defective equipment. Yes, OBVIOUSLY, defective
products can electrocute you. And it's good sense not to do things that
might expose you to equipment faults.

Many years back I had a GE toast-r-oven repaired, and the tech didn't check
the leakage. When I accidentally touched the toaster and the faucet, I got a
shock. Removing the metal side panel showed that a bare wire was touching
the metal.

In article ,
William Sommerwerck wrote:
Many years back I had a GE toast-r-oven repaired, and the tech didn't
check the leakage. When I accidentally touched the toaster and the
faucet, I got a shock. Removing the metal side panel showed that a bare
wire was touching the metal.

I've never quite understood why such things aren't grounded in the US? Or
perhaps they are now?

--
*A bartender is just a pharmacist with a limited inventory.

Dave Plowman London SW
To e-mail, change noise into sound.

Many years back I had a GE toast-r-oven repaired, and
the tech didn't check the leakage. When I accidentally
touched the toaster and the faucet, I got a shock.
Removing the metal side panel showed that a bare wire
was touching the metal.

I've never quite understood why such things aren't grounded
in the US? Or perhaps they are now?

The product was purchased 35 years ago. Household appliances generally did
not have chassis grounds.