D
David Maynard
w_tom said:
I'd be truly stunned if you ever said anything that made sense.
<snip of w-tom babble>
I'd be truly stunned if you ever said anything that made sense.
<snip of w-tom babble>
D
David Maynard
Mike said:
No sweat. Understood and accepted.
Well, we also have the 'equivalent' of 'European equivalents' available too.
I have my own version of the 'Chinese made' tirade but that's another topic.
It's a cute buzz word but the fact of the matter is it's generally cheaper,
regardless of who makes it, to run off a new board with automated
manufacturing equipment than it is to pay someone a decent wage to debug
and repair one.
But I can assure you there is a quite healthy appliance repair business in
the U.S.; just not for repairing 5 buck telephones. And I'm not so sure
that going back to the days of 60 bucks for a basic phone, with 5 buck/hr
repair wages, just so they're 'worth repairing' would be necessarily a
great thing.
M
Mike Tomlinson
w_tom <[email protected]> said:
That's because a balance has to be struck between cost and
effectiveness. To quote your own words earlier, thunderstorms in the UK
are far less frequent than in the US.
Every BT line is terminated in a NTE5 master socket. This has a spark
gap arrestor device which deals with the majority of surges.
I didn't say it was. Don't put words in my mouth. (Have you considered
taking a remedial reading class?)
M
Mike Tomlinson
w_tom <[email protected]> said:
I'll repeat my earlier question. Do you work for, or otherwise have an
interest in, a manufacturer of these whole house "protection" devices?
If the answer is yes, you should declare your interest each time you
recommend them.
It's simply not necessary in the UK. Electricity feeds to homes are
underground, not overhead, so are less prone to surges caused by
lightning strikes. It's more cost-effective to buy individual surge
protection devices for more expensive devices (stereo systems,
computers.)
Nonsense. If that were the case, such surge protectors would be
recommended by industry professionals designing new construction. I
accept they're installed in commercial enterprises and in datacentres,
where the effects of a surge would impact on the organisation's
business, but for the typical UK domestic home, they're simply not
needed.
M
Mike Tomlinson
w_tom <[email protected]> said:
Nobody said otherwise. You need to work on your reading comprehension
and stop grasping at straws to try and bolster your case.
At our Canary Islands site, we paid a lot of money for a comprehensive
earthing system consisting of multiple copper rods driven into the
ground encircling the site and linked together by a thick copper cable
to be installed (no mean feat, given that it's 8000ft high, on bedrock,
on top of a volcano) and for surge protection on the incoming mains to
be fitted. Given the value of the equipment inside, that's a sensible
precaution. This is not a domestic residence in the UK, which is the
context of the discussion.
M
Mike Tomlinson
w_tom <[email protected]> said:
exactly - *unusual*.
no, because they were cheap and nasty winmodems with capacitive coupling
to the phone line, no surge arrestors built in, no spark gaps fitted,
and no galvanic isolation.
Now it's up to the user - they can replace the modem, and optionally,
buy a plug-in surge protector which includes protection for the phone
line for another tenner or so.
We're talking about home users here. Those protectors are plugged into
two-wire extension cords available in supermarkets all over North
America for a couple of dollars. Or plugged into an outlet installed
some years ago depending on metal conduit (no separate earth wire) for
its low impedance path to earth. Or plugged into a two-pin to three-pin
adapter, again available in supermarkets everywhere. Or plugged into
one of those multi-way adapters that convert a double wall outlet into a
six-way outlet, requiring the fixing screw of the outlet to be removed
and replaced over a metal tag on the adapter to provide an "earth". Get
the idea?
The impedance might be excessive on certain installations in your
country, but UK and European installations have a good path to earth,
which is why plug-in protectors work. How many times do I have to
repeat this?
If the earth pin is so useless, how come American wiring code now
mandates the installation of three-pin outlets?
The context of the discussion is home installations, which rather
excludes the Empire State. Please try to keep up.
M
Mike Tomlinson
w_tom <[email protected]> said:
Well, you posted this link yourself, showing typical American
installations: http://www.tvtower.com/fpl.html
Power distribution to domestic properties in the UK is almost all
underground, fed from local substations. Not overhead lines and pole-
mounted transformers with dodgy connections to earth and broken surge
protectors/lightning arrestors.
Thank you for proving my point.
D
David Maynard
Mike said:
You're actually talking about two different issues here. One is surge
suppression for device protection and the other is human safety. The
primary reason for the separate earth is it's a redundant return path that
insures an earthed connection should neutral fail and, second, a protective
shield from an internal power fault to case (alternate is double
insulated). Third, it enables ground fault interrupters to work (which
senses the internal power fault to case just mentioned).
For the human safety issues the current involved is breaker/fuse limited
and different than what one might see as a lightning induced surge so the
matter of 'impedance', and whether it's 'good enough' is (potentially)
different.
Surge suppression is piggy backed on that because of the convenience, and
availability, of the earthed third wire but it isn't the originating reason
for having it.
M
Mike Tomlinson
David Maynard said:
It's a frequent lament on sci.electronics.repair.That's true, but it's a shame about the impact on the environment. And
much of this failed kit makes its way to the Third World for "recycling"
where it poisons the locals and their environment.
http://www.crra.com/ewaste/ttrash2/ttrash2/
Fortunately, I got out of the PC/monitor/printer repair industry a few
years ago when I saw the writing on the wall.
It's only with the advance of "creeping featurisation" (i.e. adding more
bells and whistles) that electronic equipment has become more complex
and thus more likely to fail.
D
David Maynard
Mike said:
I'm sure.
That article is so filled with hysterical hyperbole that I can't tell how
much, if any, of it deserves serious consideration.
Yeah. I used to do audio/visual repair quite a while back.
Just repaired two monitors though
I certainly subscribed to a similar theory with automobile 'features', like
power windows, power seats, etc. Just 'one more thing' to break.
However, with electronics it's actually not the case as reliability has
increased so much it's beyond comprehension.
For example, it was hailed as a stunning technological breakthrough when
computers finally achieved a mean time to repair shorter than the mean time
to failure, which meant they could run an 8 hour shift, shut down
operations for an 8 hour maintenance cycle, and be ready to run again the
next morning. (will wonders never cease?)
A simple PDA is orders of magnitude more powerful than that old behemoth
was but can you imagine the outcry if you had to have it repaired every 8
hours? Hell, the battery charge lasts longer than that.
Btw, the biggest driving force to what you call "creeping featurisation" is
the microcontroller (processor). Once you have one to perform the basic
functions of the device it's essentially 'free', or close to it, to throw
in some more 'feature' adding code.
L
Last Boy Scout
Keep in mind that your computer is connected to the internet and can also
get a surge through the Networking media whether that is from a DSL line or
a cable modem line. Lightning can strike the ground or even the power
station making the power, or your house. Also in some places in times of
heavy use the power company may not be making enough power thus causing
some fluctuation.
computers can handle some fluctuations in power. In the USA in the midwest
where I live we get a lot of irratic thunder storms with lots of lightning.
sometimes the power goes out and that is probably the most dangerous time
for a power surge for a computer. This is when a UPS Uninterruptible Power
Supply can help to protect your computer. Sudden outages and then when the
power tries to come back on is when damage is more likely to occur. I have
also heard of the wiring of the circuits in the house can be a factor. If
you are on the same circuit as say a refrigerator or a
airconditioner/furnace there may be some fluctuation when those devices
start up or shut off.
I have always used a surge protector but I honestly do not know how well
they are made or how much protection they afford. One good thing they
provide is a central location to plug your gear into. This way if you want
to work on your computer you know if you turn off the surge protector that
everything is off.
get a surge through the Networking media whether that is from a DSL line or
a cable modem line. Lightning can strike the ground or even the power
station making the power, or your house. Also in some places in times of
heavy use the power company may not be making enough power thus causing
some fluctuation.
computers can handle some fluctuations in power. In the USA in the midwest
where I live we get a lot of irratic thunder storms with lots of lightning.
sometimes the power goes out and that is probably the most dangerous time
for a power surge for a computer. This is when a UPS Uninterruptible Power
Supply can help to protect your computer. Sudden outages and then when the
power tries to come back on is when damage is more likely to occur. I have
also heard of the wiring of the circuits in the house can be a factor. If
you are on the same circuit as say a refrigerator or a
airconditioner/furnace there may be some fluctuation when those devices
start up or shut off.
I have always used a surge protector but I honestly do not know how well
they are made or how much protection they afford. One good thing they
provide is a central location to plug your gear into. This way if you want
to work on your computer you know if you turn off the surge protector that
everything is off.
L
Lem
Tim Auton said:
Hi Tim, I am the OP and I initially crossposted to four groups and
then found another four which seemed relevant so I crossposted to
those too.
I figured that 8 crossposted groups would evoke wrath and I know
that some newsreaders are unhappy with that number. So you are
right to point out the parallel discussion to this one. Pity they
can't be linked.
N
nigel. carron
My sister in \Cornwall (nr Helston) had a brownout) voltages of several
hundred volts over 230V apparently - lost everything connected - PC,
DVD, TV etc. Power company responsible and they did replace everything -
but they did try to replace decent stuff with cheap brands.
Surge protectors would have almost certainly saved her the hassle..
hundred volts over 230V apparently - lost everything connected - PC,
DVD, TV etc. Power company responsible and they did replace everything -
but they did try to replace decent stuff with cheap brands.
Surge protectors would have almost certainly saved her the hassle..
N
nigel. carron
Not until the power company stuff up - then its wise to go buy one - of
course nothing works for weeks whilst replaced etc.. But why waste a
fiver to prevent it!
J
Jonathan Buzzard
It might be in the USA where lightning strikes are much much more frequent
than the UK. However as with all your advice it is based on the situation
in the USA where everything is different and renders your advice almost
completely wrong.
JAB.
M
Mike Tomlinson
Bernard Peek <[email protected]> said:
Referred to by the Shermans as "knob and tube" wiring. Though I thought
the wires were insulated.
B
Bernard Peek
w_tom <[email protected]> said:
Actually these ideas predate the ESE industry by many years, which is
why the pointed lightning conductors are called Franklin rods. I've done
some more research, and it appears that you are probably correct
although the references you quote don't support your argument.
The NFPA recommended Franklin rods because they believed that they bleed
off the charge and reduce the likelihood that lightning will strike.
They found that ESE were not significantly more effective in doing that.
So the references you quoted actually supported my argument, although
later research suggests that I was wrong.
The research that suggests that lighting rods don't work that way is
much more recent. I can find references to it, but the primary research
doesn't seem to be accessible via the web.
However you are quite correct in pointing out that a properly installed
copper strap as used in lightning conductors is capable of shunting a
strike to ground. I stand corrected.
B
Bernard Peek
Bare wires passing through ceramic tubes in the floor joists. Apparently
this still meets the code in some states.
J
Jonathan Buzzard
I wondered how long it would be before you spouted rubbish again.
You point blank refuse to accept that when a kettle lead shorted out
at work, the HD15 input of a very expensive 21" monitor stopped working.
It was working fine right until the MCB and RCD tripped. When turned
back on it was not working. The building had whole earth grounding
as you claim gives all the protection you need. In reality internally
generated transients can prove fatal to equipment.
You have also failed to answer why the British Standard says that whole
building grounding is insufficient for full protection, and that sensitive
You also claim that lightning strikes are not physically destructive.
Despite many reported incidents in the press to the contrary.
The reality remains that the utility companies in the U.K. (that is
electric and telephone) do a very good job of doing proper earth grounding
of there facilities. The upshot of this is you only need to provide
sufficient extra impedance to encourage any earth seeking surge to use the
earth grounding provided by the utility companies. As such plug in surge
protectors do a sufficiently good job in the U.K.
In fact as the *vast* majority of people in the U.K. have their
electricity supply delivered underground from the substation any surge
protection on the electricity supply is entirely pointless in most cases.
Even telegraph poles are earthed, if you want I can take a photograph of
one erected recently near me, and you can clearly see the shinny copper
wire running down the side and into the ground. Even then a large
percentage of people have their telephone come in entirely underground
from the exchange so again in those cases any grounding is entirely
pointless.
JAB.
J
Jonathan Buzzard
Wrong again, the earth wire in that by law must follow all wiring in
the house is earthed at the consumer unit to earth ground.
Perfectly satisfactory. Any earth seeking surge will find the lowest
impedance path to ground. All a plug in surge protector does is increase
the impedance at that point. So the surge arives at the plug in surge
protector seeking earth ground. It has two choices, it can take the path
to earth ground provided by the surge protector at a fraction of an ohm.
Alternatively it can decided to find some other path to ground at a *much*
higher impedance (typically thousands of ohms if not more).
Basic 101 physics here, it takes the lowest impedance path to earth ground,
that is through the surge protector, job done. Surge protector might be
stuffed afterwards, but that is not the point, the valuable data on your
hard disk is safe.
Rubbish, you will only effect the impedance if you wire it in a coil.
Again you spout rubbish. The length does not matter one jot. Neither do
any joins. The only thing that counts is the impedance. As a point of note
how do you propose joining your earth wire to the grounding spike without
a join?
As pointed out many if not most plugs in an average British house are
within 6 metres of earth and due to the standard ring main wiring in
the U.K. have a much lower impedance than you would have in the U.S.A.
Further the actual impedance does not matter, provided it is sufficiently
lower than an alternative destructive route through your equipment. Again
this is 101 physics. Oh sub 1 Ohm route through the plug in surge
protector to earth ground or 10,000 Ohm route through the equipment. Your
claim is that they take the 10,000 Ohm route through the equipment because
the sub 1 Ohm route is not close enough to ground. Really w_tom you do
talk some utter and total rubbish.
Wrong indeed, they talk about earthing all the time. In fact the typical
one generally talks about safely dissipating surges to earth. Then again
as you don't live in the U.K. it is not surprising that you would not know
what they say on the box.
JAB.