Dumb Questions 57a and 57b

[Ext User(Fran)]

I've just been helping a staff member out by installing a new printer
in her "office" (a converted storeroom which had once been the
school's server room). I can find only one power point with two
outlets on it. One of them has a surge protector plugged into it, but

a) I don't see how it can protect against surges if it's not between a
machine and the power source. Is this right?

And

b) Is there any reason why I shouldn't place a power board on the
adjacent power outlett so as to make it possible to plug in the
printer and laptop the staff member will be using?

Fran

[Ext User(Trevor Wilson)]

"Fran" <Fran.Beta@gmail.com> wrote in message
news:1170359302.624931.80070@h3g2000cwc.googlegrou ps.com...
> I've just been helping a staff member out by installing a new printer
> in her "office" (a converted storeroom which had once been the
> school's server room). I can find only one power point with two
> outlets on it. One of them has a surge protector plugged into it, but
>
> a) I don't see how it can protect against surges if it's not between a
> machine and the power source. Is this right?

**No. A surge protector typically acts as a 'crowbar' device. Think of it
this way:

There's this guy with a bloody big crowbar, standing in front of an exposed
pair mains terminals. He is monitoring the mains Voltage with a high speed
measurement device. As soon as the mains Voltage exceeds a preset level, he
throws the crowbar across the terminals, thus shorting them and preventing
the surge from going any higher.

In the real world, the guy and the crowbar are replaced by solid state and
gas arrestors, which act in microseconds, to prevent the surge from reaching
the equipment. They should blow a series mains fuse.

In the real, real world, surge protectors are of limited usefulness. Do not
rely on them. Always unplug sensitive and expensive equipment, during
thunderstorms and other events.

>
> And
>
> b) Is there any reason why I shouldn't place a power board on the
> adjacent power outlett so as to make it possible to plug in the
> printer and laptop the staff member will be using?

**Nope.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[Ext User(steam3801)]

On 1 Feb 2007 11:48:22 -0800, "Fran" <Fran.Beta@gmail.com> - in a
blinding flash of brilliance - wrote:

>I've just been helping a staff member out by installing a new printer
>in her "office" (a converted storeroom which had once been the
>school's server room). I can find only one power point with two
>outlets on it. One of them has a surge protector plugged into it, but
>
>a) I don't see how it can protect against surges if it's not between a
>machine and the power source. Is this right?
>
>And
>
>b) Is there any reason why I shouldn't place a power board on the
>adjacent power outlett so as to make it possible to plug in the
>printer and laptop the staff member will be using?
>
>Fran

Remember, "surge" protectors are just that - protection against
"surges". Useless against major spikes and lightning strikes.

But, having said that - why not plug the p/brd into the surge
protector. At least that will offer token protection?
--
steam3801
ASCII a silly question, get a silly ANSI

[Ext User(Rod Speed)]

Fran <Fran.Beta@gmail.com> wrote:

> I've just been helping a staff member out by installing a new printer
> in her "office" (a converted storeroom which had once been the
> school's server room). I can find only one power point with two
> outlets on it. One of them has a surge protector plugged into it, but

> a) I don't see how it can protect against surges if it's not
> between a machine and the power source. Is this right?

Nope, it clamps the active to the earth so thats fine.

> And

> b) Is there any reason why I shouldn't place a power board
> on the adjacent power outlett so as to make it possible to
> plug in the printer and laptop the staff member will be using?

Nope.

[Ext User(lynx)]

steam3801 wrote:

> On 1 Feb 2007 11:48:22 -0800, "Fran" <Fran.Beta@gmail.com> - in a
> blinding flash of brilliance - wrote:
>
>
>> I've just been helping a staff member out by installing a new printer
>> in her "office" (a converted storeroom which had once been the
>> school's server room). I can find only one power point with two
>> outlets on it. One of them has a surge protector plugged into it, but
>>
>> a) I don't see how it can protect against surges if it's not between a
>> machine and the power source. Is this right?
>>
>> And
>>
>> b) Is there any reason why I shouldn't place a power board on the
>> adjacent power outlett so as to make it possible to plug in the
>> printer and laptop the staff member will be using?
>>
>> Fran
>>
>
> Remember, "surge" protectors are just that - protection against
> "surges". Useless against major spikes and lightning strikes.
>

Most surge protectors are also a fuse type device aren't they? If the
voltage rises too high they go open circuit usually permanently. i.e.
need replacement.

> But, having said that - why not plug the p/brd into the surge
> protector. At least that will offer token protection?
>

Many power boards have their own built in surge protection.


--

rgds,

Pete
=====
http://pw352.blogspot.com/
'In a small enough yard, even a blind hog can find a truffle'

[Ext User(LandLord)]

"lynx" <none@nothere.com> wrote in message
news:12s5544d5qkc8a9@news.supernews.com...
> steam3801 wrote:
>
>> On 1 Feb 2007 11:48:22 -0800, "Fran" <Fran.Beta@gmail.com> - in a
>> blinding flash of brilliance - wrote:
>>
>>
>>> I've just been helping a staff member out by installing a new printer
>>> in her "office" (a converted storeroom which had once been the
>>> school's server room). I can find only one power point with two
>>> outlets on it. One of them has a surge protector plugged into it, but
>>>
>>> a) I don't see how it can protect against surges if it's not between a
>>> machine and the power source. Is this right?
>>>
>>> And
>>>
>>> b) Is there any reason why I shouldn't place a power board on the
>>> adjacent power outlett so as to make it possible to plug in the
>>> printer and laptop the staff member will be using?
>>>
>>> Fran
>>>
>>
>> Remember, "surge" protectors are just that - protection against
>> "surges". Useless against major spikes and lightning strikes.
>>
>
> Most surge protectors are also a fuse type device aren't they? If the
> voltage rises too high they go open circuit usually permanently. i.e. need
> replacement.
>
>> But, having said that - why not plug the p/brd into the surge
>> protector. At least that will offer token protection?
>>
>
> Many power boards have their own built in surge protection.
>
And many many don't. All come with an lamp overload reset circuit
breaker. A must by law.

[Ext User(w_tom)]

As Trevor explained, protectors (ie crowbars) are shunt mode
devices. Electrically, the computer connects to same 'protector
circuit' if plugged into the power board OR plugged into an adjacent
wall receptacle. What is the circuit inside a protector power board?
AC plug connects directly to each AC receptacle. No protector
circuits sit between each receptacle and its AC power plug.

The problem. Those protector circuits (shunt mode devices) are only
effective when earthing a transient. Where is the earth ground?
Maybe 20 meters away via safety ground wire? Therefore much of a
surge may find other paths to earth, destructively, via adjacent
electronics. In one autopsy, we found the adjacent protector
literally shunted a surge to earth, destructively, through a network
of powered off computers. Earth ground on safety ground wire was too
far away.

Another said plug-in protectors will not protect from lightning, et
al. Correct - as the manufacturer's numerical specifications say.
Ironically, lightning, et al are the only type of surges that
typically causes computer damage. Protection already inside
computers is that robust. Internal computer protection assumes you
have earthed typically destructive surges before those surges enter
the building. IOW protection must earth each and every utility wire
1) where wires enter the building, 2) typically with a 'less than 3
meter' earthing connection, and 3) distant from protected electronics.
Protection is a building wide solution.

Again, to be effective, that power board must have a short earthing
connection. Instead it has maybe a 20 meter connection. So its
manufacturer avoids all discussion about earthing - their silence
sells more product on myths. Also required for earthing are no
splices, no sharp bends, and separated from all other wires. Wires
inside walls violate all those requirements. Just more reasons why
that protector (shunt mode) is not effectively earthed.

At this point, it should be obvious that the power board protector
does almost as much if in the rubbish bin. However it performs a
useful function. It permits many AC plugs to share one wall
receptacle. That $4 function is really what a $25 protector
accomplishes. Even better is a power board without surge protection
as demonstrated by scary pictures:
http://www.westwhitelandfire.com/Articles/Surge%20Protectors.pdf
http://www.hanford.gov/rl/?page=556&parent=554
http://www.zerosurge.com/HTML/movs.html
http://www.nmsu.edu/~safety/programs/gen_saf/surgeprotectorfire.htm

Surge protection is for type of surges that typically cause damage;
that may overwhelm protection inside appliances. That adjacent
protector does not even claim to provide such protection. It claims
to protect from transients that internal computer design makes
irrelevant.

She and you need protection. But at 'whole house' protector (for
everything in the building) must be located where the AC utility (and
Telstra) wires enter a building. And this is most important. A 'whole
house' protector makes then essential 'less than 3 meter' connection
to earth - no splices, no sharp wire bends, separated from other non-
earthing wires, not inside metallic conduit, etc. Shorter connection
means even better protection.

Lessons here apply to your home as well as to workplace protection.
It is routine to suffer direct lightning strikes and not suffer
damage. But the human must earth every incoming wire either directly
(hardwired) or via a 'whole house' protector. Others never learn this
and must therefore constantly unplug everything. Others suffered
damage and then assume the power board protector is not for lightning
protection. If not, then it has no purpose. But a protector is only
as effective as its earth ground. Your power board is only for many
appliances to one AC wall receptacle.

On Feb 1, 2:48 pm, "Fran" <Fran.B...@gmail.com> wrote:
> I've just been helping a staff member out by installing a new printer
> in her "office" (a converted storeroom which had once been the
> school's server room). I can find only one power point with two
> outlets on it. One of them has a surgeprotectorplugged into it, but
>
> a) I don't see how it can protect against surges if it's not between a
> machine and the power source. Is this right?
>
> And
>
> b) Is there any reason why I shouldn't place a power board on the
> adjacent power outlett so as to make it possible to plug in the
> printer and laptop the staff member will be using?

[Ext User(bud--)]

On Feb 2, 4:41 am, "w_tom" <w_t...@usa.net> wrote:

For reliable information on surges an surge suppression try:
http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf
- the title is "How to protect your house and its contents from
lightning: IEEE guide for surge protection of equipment connected to C
power and communication circuits" published by the IEEE in 2005 the
IEEE is the dominant organization of electrical and electronic
engineers in the US).

And
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the National
Institute of Standards and Technology (the US government agency
formerly called the National Bureau of Standards) in 2001

Both guides were intended for wide distribution to the general public
to explain surges and how to protect against them. The IEEE guide was
targeted at people who have some (not much) technical background. Some
details like grounding systems may be different in Australia but the
physics is the same.

> As Trevor explained, protectors (ie crowbars) are shunt mode
> devices.
Actually they are as described by Rod. For power circuits MOVs are
almost always used. MOVs clamp (not short) the voltage across them.

>
> The problem. Those protector circuits (shunt mode devices) are only
> effective when earthing a transient. Where is the earth ground?
> Maybe 20 meters away via safety ground wire? Therefore much of a
> surge may find other paths to earth, destructively, via adjacent
> electronics. In one autopsy, we found the adjacent protector
> literally shunted a surge to earth, destructively, through a network
> of powered off computers. Earth ground on safety ground wire was too
> far away.
To the contrary, both the IEEE and NIST guides say plug-in suppressors
are effective.
As is described in the IEEE guide, plug-in suppressors work by
clamping the voltage on all wires (signal and power) to the common
ground at the suppressor. They do not work primarily by earthing.

Note that interconnected equipment needs to be connected to the same
plug-in suppressor, or interconnecting wires, like LAN need to go
through the suppressor. Other external wires like phone, cable TV, ...
also need to go thorough the suppressor. The voltage on ALL wires to a
protected device needs to be clamped to the common ground. This is
described in both guides.


>
> Another said plug-in protectors will not protect from lightning, et
> al. Correct - as the manufacturer's numerical specifications say.
Steam and w_ are both wrong. Read the guides. Plug-in surge
suppressors come in ratings from junk to very high. At high ratings a
suppressor should protect against anything but a very near strike.


>
> Again, to be effective, that power board must have a short earthing
> connection. Instead it has maybe a 20 meter connection. So its
> manufacturer avoids all discussion about earthing - their silence
> sells more product on myths.
The myths come from w_. Plug-in suppressors work by clamping, not
earthing. And both the IEEE and NIST say plug-in suppressors are
effective.


> Even better is a power board without surge protection
> as demonstrated by scary pictures:
If you have no technical arguments try pathetic scare tactics.

> http://www.westwhitelandfire.com/Articles/Surge%20Protectors.pdf
> http://www.hanford.gov/rl/?page=556&parent=554
> http://www.zerosurge.com/HTML/movs.html
> http://www.nmsu.edu/~safety/programs/gen_saf/surgeprotectorfire.htm
For anyone with minimal reading skills the hanford link talks about
"some older model" power strips and specifically references the
revised UL standard, effective 1998, that requires a thermal
disconnect as a fix for overheating MOVs. Overheating was fixed in the
US in 1998. w_ can't understand his own links

None of these links indicate the problem suppressors shown had UL
labels. And none of these links say there is any problem with
suppressors under the current UL standard (check Australian
standards). Or that plug-in suppressors shouldn't be used. The links
do give info on how to use plug-in suppressors.

>
> Surge protection is for type of surges that typically cause damage;
> that may overwhelm protection inside appliances. That adjacent
> protector does not even claim to provide such protection. It claims
> to protect from transients that internal computer design makes
> irrelevant.
More rubbish. Suppressors are readily available with very high ratings
and many (at least in the US) have guarantees.


> But a protector is only
> as effective as its earth ground. Your power board is only for many
> appliances to one AC wall receptacle.
If w_ could read he could figure out plug-in suppressors don't work by
earthing.
Both the IEEE and NIST guides say plug-in suppressors are effective.

--
bud--

[Ext User(Rod Speed)]

LandLord <apub@sydney> wrote:
> "lynx" <none@nothere.com> wrote in message
> news:12s5544d5qkc8a9@news.supernews.com...
>> steam3801 wrote:
>>
>>> On 1 Feb 2007 11:48:22 -0800, "Fran" <Fran.Beta@gmail.com> - in a
>>> blinding flash of brilliance - wrote:
>>>
>>>
>>>> I've just been helping a staff member out by installing a new
>>>> printer in her "office" (a converted storeroom which had once been
>>>> the school's server room). I can find only one power point with two
>>>> outlets on it. One of them has a surge protector plugged into it,
>>>> but a) I don't see how it can protect against surges if it's not
>>>> between a machine and the power source. Is this right?
>>>>
>>>> And
>>>>
>>>> b) Is there any reason why I shouldn't place a power board on the
>>>> adjacent power outlett so as to make it possible to plug in the
>>>> printer and laptop the staff member will be using?
>>>>
>>>> Fran
>>>>
>>>
>>> Remember, "surge" protectors are just that - protection against
>>> "surges". Useless against major spikes and lightning strikes.
>>>
>>
>> Most surge protectors are also a fuse type device aren't they? If the
>> voltage rises too high they go open circuit usually permanently.
>> i.e. need replacement.
>>
>>> But, having said that - why not plug the p/brd into the surge
>>> protector. At least that will offer token protection?
>>>
>>
>> Many power boards have their own built in surge protection.
>>
> And many many don't. All come with an lamp overload reset circuit
> breaker. A must by law.

Nope on that last.

[Ext User(lynx)]

LandLord wrote:

> "lynx" <none@nothere.com> wrote in message
> news:12s5544d5qkc8a9@news.supernews.com...
>
>> steam3801 wrote:
>>
>>> On 1 Feb 2007 11:48:22 -0800, "Fran" <Fran.Beta@gmail.com> - in a
>>> blinding flash of brilliance - wrote:
>>>
>>>> I've just been helping a staff member out by installing a new printer
>>>> in her "office" (a converted storeroom which had once been the
>>>> school's server room). I can find only one power point with two
>>>> outlets on it. One of them has a surge protector plugged into it, but
>>>>
>>>> a) I don't see how it can protect against surges if it's not between a
>>>> machine and the power source. Is this right?
>>>>
>>>> And
>>>>
>>>> b) Is there any reason why I shouldn't place a power board on the
>>>> adjacent power outlett so as to make it possible to plug in the
>>>> printer and laptop the staff member will be using?
>>>>
>>>> Fran
>>>>
>>> Remember, "surge" protectors are just that - protection against
>>> "surges". Useless against major spikes and lightning strikes.
>>>
>> Most surge protectors are also a fuse type device aren't they? If the
>> voltage rises too high they go open circuit usually permanently. i.e. need
>> replacement.
>>
>>> But, having said that - why not plug the p/brd into the surge
>>> protector. At least that will offer token protection?
>>>
>> Many power boards have their own built in surge protection.
>>
>>
> And many many don't. All come with an lamp overload reset circuit
> breaker. A must by law.
>

The point- that I thought was obvious- was that she could get a power
board with surge protection if she wanted. The fact that there are many
without it is irrelevant, as was your comment.


--

rgds,

Pete
=====
http://pw352.blogspot.com/
'It's called PMT because 'mad cow disease' is already taken'

[Ext User(Fran)]

On Feb 2, 7:32 am, "Trevor Wilson" <tre...@SPAMBLOCKrageaudio.com.au>
wrote:
> "Fran" <Fran.B...@gmail.com> wrote in message
>
> news:1170359302.624931.80070@h3g2000cwc.googlegrou ps.com...
>
> > I've just been helping a staff member out by installing a new printer
> > in her "office" (a converted storeroom which had once been the
> > school's server room). I can find only one power point with two
> > outlets on it. One of them has a surge protector plugged into it, but
>
> > a) I don't see how it can protect against surges if it's not between a
> > machine and the power source. Is this right?
>
> **No. A surge protector typically acts as a 'crowbar' device. Think of it
> this way:
>
> There's this guy with a bloody big crowbar, standing in front of an exposed
> pair mains terminals. He is monitoring the mains Voltage with a high speed
> measurement device. As soon as the mains Voltage exceeds a preset level, he
> throws the crowbar across the terminals, thus shorting them and preventing
> the surge from going any higher.
>
> In the real world, the guy and the crowbar are replaced by solid state and
> gas arrestors, which act in microseconds, to prevent the surge from reaching
> the equipment. They should blow a series mains fuse.
>
> In the real, real world, surge protectors are of limited usefulness. Do not
> rely on them. Always unplug sensitive and expensive equipment, during
> thunderstorms and other events.
>
>
>
> > And
>
> > b) Is there any reason why I shouldn't place a power board on the
> > adjacent power outlett so as to make it possible to plug in the
> > printer and laptop the staff member will be using?
>
> **Nope.
>
> --
> Trevor Wilsonwww.rageaudio.com.au
>
> --
> Posted via a free Usenet account fromhttp://www.teranews.com

Thanks Trevor, and all the others in this topic, for you observations.

The surge protector is one of those built in type things about the
dimensions of a chessboard and fixed to the wall, plugged in to the
powerpoint.

Fran

[Ext User(w_tom)]

On Feb 2, 5:52 pm, lynx <n...@nothere.com> wrote:
> The point- that I thought was obvious- was that she could get a power
> board with surge protection if she wanted. The fact that there are many
> without it is irrelevant, as was your comment.

But the comment was about a fuse - something that must be in all
power boards. High voltage does not blow (open) a fuse. Fuse is for
human safety. Fuse may blow after an appliance fails so that the
failed appliance does not start a fire; does not kill the human.

Fuse may also blow, eventually, after this other problem with surge
protector boards:
http://www.hanford.gov/rl/?page=556&parent=554
http://www.westwhitelandfire.com/Articles/Surge%20Protectors.pdf
http://www.ddxg.net/old/surge_protectors.htm
http://www.zerosurge.com/HTML/movs.html
However, scary pictures demonstrate that fuse sometimes does not trip
fast enough.

Fuse has no relationship to surge protection. Surge protection
(that includes the necessary earthing) is installed so that damage
does not occur. Fuse restricts a human safety threat after damage has
occurred.

[Ext User(Tsunami Australia)]

Rod Speed wrote:
> Fran <Fran.Beta@gmail.com> wrote:
>
>> I've just been helping a staff member out by installing a new printer
>> in her "office" (a converted storeroom which had once been the
>> school's server room). I can find only one power point with two
>> outlets on it. One of them has a surge protector plugged into it, but
>
>> a) I don't see how it can protect against surges if it's not
>> between a machine and the power source. Is this right?
>
> Nope, it clamps the active to the earth so thats fine.
>
>> And
>
>> b) Is there any reason why I shouldn't place a power board
>> on the adjacent power outlett so as to make it possible to
>> plug in the printer and laptop the staff member will be using?
>
> Nope.
>
>

The issue I see is if it is an old building and happens to be using
fuses rather than breakers. Fuses are notorious for "NOT" blowing when
the shit hits the fan. I've seen this myself many times, even been
bitten by a device which was leaking straight to earth and had been for
some minutes.

[Ext User(w_tom)]

On Feb 5, 6:55 am, Tsunami Australia <tsunami_australi...@yahoo.com-
dot-au> wrote:
> The issue I see is if it is an old building and happens to be using
> fuses rather than breakers. Fuses are notorious for "NOT" blowing when
> the shit hits the fan. I've seen this myself many times, even been
> bitten by a device which was leaking straight to earth and had been for
> some minutes

The original post asks:
> I don't see how it can protect against surges if it's not between
> a machine and the power source. Is this right?

But fuses are not and never were surge protection. Surges do their
damage in microseconds. Fuses and circuit breakers take milliseconds
to respond. Fuses and circuit breakers are for disconnecting
electricity AFTER damage has occurred.

Surge protection is about shunting (diverting, connecting, clamping,
conducting) a surge to earth ground so that surge does not flow
through appliances. Fuses and circuit breakers were never intended
for such functions. Fuses are so that the damage does not kill
humans.

If it is an old building, then it may not have properly earthing -
therefore no surge protection. Essential is the 'less than 3 meter'
earthing connection - as was necessary even in 1930s where direct
lightning strikes resulted in no damage.

[Ext User(bud--)]

On Feb 4, 7:30 am, "w_tom" <w_t...@usa.net> wrote:
> On Feb 5, 6:55 am, Tsunami Australia <tsunami_australi...@yahoo.com-
>
> dot-au> wrote:
> > The issue I see is if it is an old building and happens to be using
> > fuses rather than breakers. Fuses are notorious for "NOT" blowing when
> > the shit hits the fan. I've seen this myself many times, even been
> > bitten by a device which was leaking straight to earth and had been for
> > some minutes
>
> The original post asks:
>
> > I don't see how it can protect against surges if it's not between
> > a machine and the power source. Is this right?
>
> But fuses are not and never were surge protection. Surges do their
> damage in microseconds. Fuses and circuit breakers take milliseconds
> to respond. Fuses and circuit breakers are for disconnecting
> electricity AFTER damage has occurred.
I agree that fuses and circuit breakers do no provide surge
protection.

>
> Surge protection is about shunting (diverting, connecting, clamping,
> conducting) a surge to earth ground so that surge does not flow
> through appliances. Fuses and circuit breakers were never intended
> for such functions. Fuses are so that the damage does not kill
> humans.
>
> If it is an old building, then it may not have properly earthing -
> therefore no surge protection. Essential is the 'less than 3 meter'
> earthing connection - as was necessary even in 1930s where direct
> lightning strikes resulted in no damage.
Still unable to understand how plug-in surge protectors work w_
repeats his religious belief in earthing.

The IEEE guide on surges and surge protection at
http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversio...
says plug-in surge protectors work by clamping the voltage on all
wires to the common ground at the surge protector. They do not work
primarily by earthing.

--
bud--

[Ext User(Tsunami Australia)]

bud-- wrote:
> On Feb 4, 7:30 am, "w_tom" <w_t...@usa.net> wrote:
>> On Feb 5, 6:55 am, Tsunami Australia <tsunami_australi...@yahoo.com-
>>
>> dot-au> wrote:
>>> The issue I see is if it is an old building and happens to be using
>>> fuses rather than breakers. Fuses are notorious for "NOT" blowing when
>>> the shit hits the fan. I've seen this myself many times, even been
>>> bitten by a device which was leaking straight to earth and had been for
>>> some minutes
>> The original post asks:
>>
>>> I don't see how it can protect against surges if it's not between
>>> a machine and the power source. Is this right?
>> But fuses are not and never were surge protection. Surges do their
>> damage in microseconds. Fuses and circuit breakers take milliseconds
>> to respond. Fuses and circuit breakers are for disconnecting
>> electricity AFTER damage has occurred.
> I agree that fuses and circuit breakers do no provide surge
> protection.
>
>> Surge protection is about shunting (diverting, connecting, clamping,
>> conducting) a surge to earth ground so that surge does not flow
>> through appliances. Fuses and circuit breakers were never intended
>> for such functions. Fuses are so that the damage does not kill
>> humans.
>>
>> If it is an old building, then it may not have properly earthing -
>> therefore no surge protection. Essential is the 'less than 3 meter'
>> earthing connection - as was necessary even in 1930s where direct
>> lightning strikes resulted in no damage.
> Still unable to understand how plug-in surge protectors work w_
> repeats his religious belief in earthing.
>
> The IEEE guide on surges and surge protection at
> http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversio...
> says plug-in surge protectors work by clamping the voltage on all
> wires to the common ground at the surge protector. They do not work
> primarily by earthing.
>
> --
> bud--
>
>
>

What I was getting at was I would assume that part of the crowbar
protection would at some stage rely on fuses/breakers for an extended
surge. I was thinking this due to my old days of screwing around that
active and earth mixed did weird things. But with some resistance
between them I can see how things change.