Surge protection without grounded plugs

[w_tom]

On Sep 23, 3:48 pm, David Schwartz <david...@gmail.com> wrote:

.... My take is that:
- a plug-in surge protector of any type won't protect my son's
computer
- what is required is for the entire house to be surge protected
before the power enters the house.

Are these the correct conclusions?

Points are correct IF surges are the problem. But surges have
nothing to do with unreliable wiring. Surges are sourced externally.
Unreliable wiring is an internal problem.

Also irrelevant are surges from household appliances such as
motors. If those were destructive, then everyone here is trooping
daily to the hardware store to replace clock radios and dimmer
switches. Protection already inside all appliances makes those motor
'surges' completely irrelevant.

Unreliable wiring would create problems such as power loss, fire, or
repeated circuit breaker tripping. Those internally generated events
are different externally sourced events such as surges. One symptom
of unreliable wiring is extension cords - a common source of fire and
why Arc Fault circuit breakers are now required for bedroom circuits.
Ground fault breakers are a solution for circuits that are only two
wire - do not have the safety ground wire. Also a threat are multiple
outlet connectors (such as power strips) that do not have the 15 amp
circuit breaker.

As noted repeatedly (and why HowStuffWorks is so embarrassing), all
appliances contain internal protection. Computers are particularly
robust. Protection for all appliances means earthing anything so
massive as to cause failures. Surges that may overwhelm protection
inside electronic appliances must be earthed before entering the
building. Those destructive surges typically occur once every seven
years - a number that varies significantly even within the same town.
We earth 'whole house' protection for that rare event.

Again, every incoming utility wire must be earthed. Telco
'installed for free' protector must connect each phone wire to same
earth ground used by AC electric and cable TV. Destructive type of
surge seeks earth ground. It is not stopped or absorbed. It must be
diverted or shunted to earth. A little one inch part inside a 'magic
box' does not even claim to stop or absorb what three miles of sky
could not. Connect every incoming wire inside every cable to earth
ground either directly (cable TV, satellite dish) or via a protector
(AC electric, telephone).

 

[w_tom]

On Sep 23, 3:48 pm, David Schwartz <david...@gmail.com> wrote:

.... My take is that:
- a plug-in surge protector of any type won't protect my son's
computer
- what is required is for the entire house to be surge protected
before the power enters the house.

Are these the correct conclusions?

Points are correct IF surges are the problem. But surges have
nothing to do with unreliable wiring. Surges are sourced externally.
Unreliable wiring is an internal problem.

Also irrelevant are surges from household appliances such as
motors. If those were destructive, then everyone here is trooping
daily to the hardware store to replace clock radios and dimmer
switches. Protection already inside all appliances makes those motor
'surges' completely irrelevant.

Unreliable wiring would create problems such as power loss, fire, or
repeated circuit breaker tripping. Those internally generated events
are different externally sourced events such as surges. One symptom
of unreliable wiring is extension cords - a common source of fire and
why Arc Fault circuit breakers are now required for bedroom circuits.
Ground fault breakers are a solution for circuits that are only two
wire - do not have the safety ground wire. Also a threat are multiple
outlet connectors (such as power strips) that do not have the 15 amp
circuit breaker.

As noted repeatedly (and why HowStuffWorks is so embarrassing), all
appliances contain internal protection. Computers are particularly
robust. Protection for all appliances means earthing anything so
massive as to cause failures. Surges that may overwhelm protection
inside electronic appliances must be earthed before entering the
building. Those destructive surges typically occur once every seven
years - a number that varies significantly even within the same town.
We earth 'whole house' protection for that rare event.

Again, every incoming utility wire must be earthed. Telco
'installed for free' protector must connect each phone wire to same
earth ground used by AC electric and cable TV. Destructive type of
surge seeks earth ground. It is not stopped or absorbed. It must be
diverted or shunted to earth. A little one inch part inside a 'magic
box' does not even claim to stop or absorb what three miles of sky
could not. Connect every incoming wire inside every cable to earth
ground either directly (cable TV, satellite dish) or via a protector
(AC electric, telephone).

 

[David Schwartz]

My son just moved into an older house near his college. We're told
that the electricity isn't entirely reliable and that he should use a
surge protector.

The house's plugs aren't grounded. Will this affect the efficacy of a
surge protector?
Is the computer at risk or just the AC adapter?

Any recommendations would be appreciated.

TIA,
David

 

[Chris]

On Sep 22, 12:37 pm, David Schwartz <david...@gmail.com> wrote:

My son just moved into an older house near his college. We're told
that the electricity isn't entirely reliable and that he should use a
surge protector.

The house's plugs aren't grounded. Will this affect the efficacy of a
surge protector?
Is the computer at risk or just the AC adapter?

Any recommendations would be appreciated.

TIA,
David

Hi, Dave. Surge protectors are supposed to work by absorbing the
energy of voltage spikes caused by lightning and such. A typical
surge protector will absorb the extra energy of the spike, and shunt
the current to ground. That means they're not too useful without the
GND pin on the plug.

But voltage spikes probably aren't the problem here. This sounds more
like bad wiring, unbalanced loading of the pole transformer, or poor/
intermittent connections to the line neutral of the transformer. That
will mean the line voltage at the plug may go way up or way down,
depending on loading, humidity/condensation, the phase of the moon, or
whatever. Surge protectors don't do anything about undervoltage,
which can destroy a PC as easily as overvoltage. And if the voltage
gets high enough, the surge protector will just be destroyed by
sustained overvoltage.

I'd really suggest the house wiring get checked out by someone
competent. After all, your kid is going to be living there.

Barring that, and assuming they've got working smoke detectors there
(check yourself), a line conditioner might be a better choice for
protecting the computer. A line conditioner is an autotransformer
that senses the incoming line voltage, and switches taps (raising or
lowering the voltage) to compensate. Since a college kid's computer
is a mission-critical piece of equipment, the money will be well
spent. For a standard computer and laptop setup, one like the
TrippLite LC1200 should be sufficient. If the system's a laptop only,
you can get away with less.

When you've got kids, there's no safety this side of the grave, I
guess.

Good luck
Chris

 

[Eeyore]

Chris wrote:

David Schwartz <david...@gmail.com> wrote:
My son just moved into an older house near his college. We're told
that the electricity isn't entirely reliable and that he should use a
surge protector.

The house's plugs aren't grounded. Will this affect the efficacy of a
surge protector?
Is the computer at risk or just the AC adapter?

Any recommendations would be appreciated.


Hi, Dave. Surge protectors are supposed to work by absorbing the
energy of voltage spikes caused by lightning and such. A typical
surge protector will absorb the extra energy of the spike, and shunt
the current to ground.

It does no such thing at all.

A typical varistor based surge protector works by clamping the live to neutral
voltage. Diverting current to ground is potentially hazardous.

Here's an example. Note that the ground simply passes through with no connection
to the protection components. The one shown also has a gas discharge tube.
http://www.epanorama.net/documents/surge/surge_ac.html

Graham

 

[Paul E. Schoen]

"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:46F570D9.9CCFCB61@hotmail.com...

Chris wrote:

David Schwartz <david...@gmail.com> wrote:
My son just moved into an older house near his college. We're told
that the electricity isn't entirely reliable and that he should use a
surge protector.

The house's plugs aren't grounded. Will this affect the efficacy of a
surge protector?
Is the computer at risk or just the AC adapter?

Any recommendations would be appreciated.


Hi, Dave. Surge protectors are supposed to work by absorbing the
energy of voltage spikes caused by lightning and such. A typical
surge protector will absorb the extra energy of the spike, and shunt
the current to ground.

It does no such thing at all.

A typical varistor based surge protector works by clamping the live to
neutral
voltage. Diverting current to ground is potentially hazardous.

Here's an example. Note that the ground simply passes through with no
connection
to the protection components. The one shown also has a gas discharge
tube.
http://www.epanorama.net/documents/surge/surge_ac.html

Graham

Here's another one that does not rely on the safety ground:

http://brickwall.com/howwork.htm

There is some good info here:

http://www.mcgsurge.com/mcg_faq.htm
http://computer.howstuffworks.com/surge-protector.htm/printable
http://www.totse.com/en/technology/computer_technology/surge.html
http://www.surgeassure.com/faq.asp

If the two-prong outlets cannot be rewired, it might be a good idea to
connect an external safety ground to the chassis of the computer or other
appliance. A cold water pipe might be good enough, especially if it is
copper. Otherwise a driven ground rod is pretty good. A UPS might be
another option, especially if the power is noisy or intermittent. But the
safest option is a properly installed electrical system.

Paul

 

[w_tom]

On Sep 22, 1:37 pm, David Schwartz <david...@gmail.com> wrote:

My son just moved into an older house near his college. We're told
that the electricity isn't entirely reliable and that he should use a
surge protector.

The house's plugs aren't grounded. Will this affect the efficacy of a
surge protector?
Is the computer at risk or just the AC adapter?

Myth purveyors will claim that a surge protector will absorb energy.
Energy that could not be stopped even by three miles of sky.
Protectors don't stop or absorb surges (except where myths are
promoted). Protection means surges are earthed before entering the
building. That energy must be dissipated somewhere. That somewhere
is earth ground.

A protector is nothing more than a connecting device to protection.
Protection is earth ground - where energy is absorbed. Essential is
to have breaker box earthing upgraded to both meet and exceed post
1990 NEC code. That means an earthing electrode with a 'less than 10
foot' connection to the breaker box. Chances are the only earthing
(if it still exists) was to a cold water pipe. That earthing is no
longer sufficient even for human safety. For transistor safety, one
'whole house' protector connected to that upgraded earthing means
massive transistor protection. Protection without rewiring the entire
house.

Every incoming utility must enter at a same location to also make
that short earthing connection. For example, the phone line has a
'whole house' protector installed for free by the telco. But that
protector, also, is only as effective as its earth ground. Even the
cable must be earthed to that same electrode before entering the
building. Cable is protected without a protector. No reason for a
cable protector. Cable is earthed directly with no protector. Again,
what provides the protection? A box? No. Earthing is the
protection.

What even makes a Franklin lightning rod effective? Sharp or blunt
rod? Not relevant. Even a lightning rod is only as effective as its
earth ground because earthing provides the protection.

Do not confuse safety ground in AC wall receptacles with earth
ground. They are electrically different. That AC wall safety ground
is for human safety. No surge protector will correct that missing
safety ground. Far more useful on 'that' unreliable wiring is to
replace selective circuit breakers with Arc fault breakers or GFCI
breakers. Unreliable wiring is a human safety problem. A surge
protector accomplishes zero. But again, read numeric specs for that
surge protector. What does it actually claim to accomplish? Don't
read its color glossy sales brochure. What do its numeric specs says
it does?

It would help if you define which problem needs protection from AND
to define "unreliable wiring". A breaker box GFCI circuit breaker
goes a long way to protecting from unreliable wiring. An arc fault
type is even better protection. The plug-in surge proetctor does
nothing. It's own manufacturer will (quitely) recommend not using a
power strip protector if receptacles are not three wire - a human
safety threat created by connecting a three prong power strip to a two
prong outlet.

Surge protectors are only connecting devices to protection. That
protection is earth ground. If too far away from earth ground, a
surge proetctor must shunt somewhere. It may shunt (connect, divert,
clamp) a surge to earth via the computer. The effective protector
earths before surges can enter the building. A surge properly earthed
will not be inside the building to overwhelm protection already inside
all appliances. All appliances contain any protection that would work
on its power cord. Internal protection that may be overwhelm if the
rare and destructive surge is not earthed BEFORE entering the
building.

 

[w_tom]

On Sep 22, 5:42 pm, "Paul E. Schoen" <pst...@smart.net> wrote:

There is some good info here:
...
http://computer.howstuffworks.com/surge-protector.htm/printable

Please do not cite HowStuffWorks as honest or accurate. It even
contradicts what your other citations say. It is so full of outright
lies and myths that this criticism only address the errors from a
first few pages:

Experience with household appliances exposes those myths - described
in: "Computer problem need help" posted on 1 Aug 2002:
http://tinyurl.com/yqyah

HowStuffWorks on surge protectors is riddled with errors. One
example is obvious based upon what happens in your own home.
From HowStuffWorks:
A more common cause of power surges is the operation of
high-power electrical devices, such as elevators, air
conditioners and refrigerators.

 

[Paul E. Schoen]

"w_tom" <w_tom1@usa.net> wrote in message
news:1190564721.986120.219290@g4g2000hsf.googlegroups.com...

On Sep 22, 5:42 pm, "Paul E. Schoen" <pst...@smart.net> wrote:
There is some good info here:
...
http://computer.howstuffworks.com/surge-protector.htm/printable

Please do not cite HowStuffWorks as honest or accurate. It even
contradicts what your other citations say. It is so full of outright
lies and myths that this criticism only address the errors from a
first few pages:

Experience with household appliances exposes those myths - described
in: "Computer problem need help" posted on 1 Aug 2002:
http://tinyurl.com/yqyah

HowStuffWorks on surge protectors is riddled with errors. One
example is obvious based upon what happens in your own home.
From HowStuffWorks:
A more common cause of power surges is the operation of
high-power electrical devices, such as elevators, air
conditioners and refrigerators.

I agree that "How stuff works" is not the best, but motor loads can and do
create power surges. The surge may appear on the same phase as the load,
due to inductive "kick", but also the starting current in one phase can
cause enough voltage drop through the neutral to produce a higher voltage
in the opposite phase. If the neutral line is damaged or improperly
connected, the two 120V legs may be unbalanced depending on the individual
loads.

Paul

 

[David Schwartz]

As I'm not an electrician (that should be obvious from my initial
post), I admit to having a hard time sifting through all of this
stuff. My take is that:

- a plug-in surge protector of any type won't protect my son's
computer
- what is required is for the entire house to be surge protected
before the power enters the house.

Are these the correct conclusions?

TIA,
David

 

[Paul E. Schoen]

"David Schwartz" <davids58@gmail.com> wrote in message
news:1190576917.961357.319470@k79g2000hse.googlegroups.com...

As I'm not an electrician (that should be obvious from my initial
post), I admit to having a hard time sifting through all of this
stuff. My take is that:

- a plug-in surge protector of any type won't protect my son's
computer
- what is required is for the entire house to be surge protected
before the power enters the house.

Are these the correct conclusions?

There are several kinds of power problems, and each one has certain risks
and means of protection.

A surge protector for the entire house, at the service entrance, is
probably the best, because it deals with the surge before it enters the
rest of the wiring. But it is expensive and requires an electrician to
install it.

Properly installed and grounded wiring is very important, for the safety of
humans as well as equipment. It would be worthwhile to rewire the circuit
that feeds the computer, or even run a new line, if possible. Depending on
the age of the house, it's possible that the wiring could be aluminum,
which often develops poor connections, and can cause all sorts of problems,
including fire.

Surges from lightning are the most serious, and it is difficult to achieve
100% protection. The best method is to unplug the computer, and remove any
phone lines or other external connections. I have even had computer
speakers damaged by a close lightning strike that also damaged my modem.

Plug-in surge protectors offer some level of protection. I have a surge
protector and a UPS on my computer, and they probably helped, but the main
surge probably came in through the phone line, which was actually damaged
and required a repair to the cable from the pole to the house.

I have pictures of the damage caused by the lightning. It apparently came
down the wet bark of a huge sycamore tree, and then arced to the phone line
as well as the power lines (and blew open the neutral):

http://www.smart.net/~pstech/Lightning/

Paul

 

[Eeyore]

David Schwartz wrote:

As I'm not an electrician (that should be obvious from my initial
post), I admit to having a hard time sifting through all of this
stuff. My take is that:

- a plug-in surge protector of any type won't protect my son's
computer

From WHAT ? Gremlins ? Why do you think that ?

- what is required is for the entire house to be surge protected
before the power enters the house.

Are these the correct conclusions?

It all depends what level of protection you want.

Graham

 

[Jon Slaughter]

"w_tom" <w_tom1@usa.net> wrote in message
news:1190563527.773185.113820@22g2000hsm.googlegroups.com...

On Sep 22, 1:37 pm, David Schwartz <david...@gmail.com> wrote:
My son just moved into an older house near his college. We're told
that the electricity isn't entirely reliable and that he should use a
surge protector.

The house's plugs aren't grounded. Will this affect the efficacy of a
surge protector?
Is the computer at risk or just the AC adapter?

Myth purveyors will claim that a surge protector will absorb energy.
Energy that could not be stopped even by three miles of sky.
Protectors don't stop or absorb surges (except where myths are
promoted). Protection means surges are earthed before entering the
building. That energy must be dissipated somewhere. That somewhere
is earth ground.

A protector is nothing more than a connecting device to protection.
Protection is earth ground - where energy is absorbed. Essential is
to have breaker box earthing upgraded to both meet and exceed post
1990 NEC code. That means an earthing electrode with a 'less than 10
foot' connection to the breaker box. Chances are the only earthing
(if it still exists) was to a cold water pipe. That earthing is no
longer sufficient even for human safety. For transistor safety, one
'whole house' protector connected to that upgraded earthing means
massive transistor protection. Protection without rewiring the entire
house.

Every incoming utility must enter at a same location to also make
that short earthing connection. For example, the phone line has a
'whole house' protector installed for free by the telco. But that
protector, also, is only as effective as its earth ground. Even the
cable must be earthed to that same electrode before entering the
building. Cable is protected without a protector. No reason for a
cable protector. Cable is earthed directly with no protector. Again,
what provides the protection? A box? No. Earthing is the
protection.

What even makes a Franklin lightning rod effective? Sharp or blunt
rod? Not relevant. Even a lightning rod is only as effective as its
earth ground because earthing provides the protection.

Do not confuse safety ground in AC wall receptacles with earth
ground. They are electrically different. That AC wall safety ground
is for human safety. No surge protector will correct that missing
safety ground. Far more useful on 'that' unreliable wiring is to
replace selective circuit breakers with Arc fault breakers or GFCI
breakers. Unreliable wiring is a human safety problem. A surge
protector accomplishes zero. But again, read numeric specs for that
surge protector. What does it actually claim to accomplish? Don't
read its color glossy sales brochure. What do its numeric specs says
it does?

It would help if you define which problem needs protection from AND
to define "unreliable wiring". A breaker box GFCI circuit breaker
goes a long way to protecting from unreliable wiring. An arc fault
type is even better protection. The plug-in surge proetctor does
nothing. It's own manufacturer will (quitely) recommend not using a
power strip protector if receptacles are not three wire - a human
safety threat created by connecting a three prong power strip to a two
prong outlet.

Surge protectors are only connecting devices to protection. That
protection is earth ground. If too far away from earth ground, a
surge proetctor must shunt somewhere. It may shunt (connect, divert,
clamp) a surge to earth via the computer. The effective protector
earths before surges can enter the building. A surge properly earthed
will not be inside the building to overwhelm protection already inside
all appliances. All appliances contain any protection that would work
on its power cord. Internal protection that may be overwhelm if the
rare and destructive surge is not earthed BEFORE entering the
building.

You don't have any clue what your talking about? Really, be honest!

The earth ground is only there for a direct ground reference and a low
resistance path to ground.

The problem with neutral and hot is that if they are wired incorrectly they
can easily kill someone. By having a direct reference to ground you can
eliminate this if it is used properly. It also supplies a lower resistance
to ground than the neutral(atleast as far as I have seen in my own house).

But in any case an earth ground an a neutral are identical in most cases
except for some small potential difference(atleast they should be in any
properly wired home).

I suggest you read up on

http://en.wikipedia.org/wiki/Ground_and_neutral

As far as surges go, you have essentially varistors that provide a very low
resistance path for a high voltage spike. This essentially takes out the
load after the varistor preventing(hopefully) most of the current from going
through the load.

For example, if you have

Hot -------+---- Load---+
| |
Varistor |
| |
Neutral ---+------------+


And if a large voltage spike occurs then the varistor acts somewhat as a
short essentially resulting in a short from hot to neutral and therefor
essentially dissconnecting the load from the mains. (atleast in theory it
would do that)


This has nothing to do with ground and you could even tie the varistor from
ground to netural(although it would not work if the ground was cut).

The varistor only stops surges though and doesn't protect in other others.
If the varistor breaks then so do the surge protection.

In any case "surge" protection doesn't need ground as netural is suppose to
be approximately equivilent to ground. The reason for "earth ground" in a
plug is for safety reasons and not surge protection.

Its a fact that neutral must also exist to complete the circuit so you can
always get surge protection... its also true that simple surge protectors
are not all that great. Using a simple MOV doesn't protect the load all that
great but its better than nothing and can't hurt.

So if the OP is only concerned with surge protection then he can do that by
buying good surge protectors... having earth ground isn't going to have any
effect except it could potentially make the surge protector a little better
if it was designed to use it. Maybe it could use a something like



+ -----+
/ \
MOV1 MOV2
/ \
- -+--MOV3-+--GND


Where if the ground was hooked up properly then you'll have better surge
protection... but there are better methods.

The extra earth on plugs is only for safety.

 

[ehsjr]

David Schwartz wrote:

As I'm not an electrician (that should be obvious from my initial
post), I admit to having a hard time sifting through all of this
stuff. My take is that:

- a plug-in surge protector of any type won't protect my son's
computer
- what is required is for the entire house to be surge protected
before the power enters the house.

Are these the correct conclusions?

TIA,
David

No. You don't know if the "unreliability" you heard about
has to do with surges or not. Suppose, for example, that
"unreliability" means there are frequent power outages.
All the surge protection in the world won't address that
problem.

If you want to use surge protectors, the IEEE recommends
that you use both whole house and point of use protectors.

Ed

 

[bud--]

w_tom wrote:

On Sep 22, 1:37 pm, David Schwartz <david...@gmail.com> wrote:

My son just moved into an older house near his college. We're told
that the electricity isn't entirely reliable and that he should use a
surge protector.

As others have noted, the problem may be surges or may be other power
problems. How common are lightning storms?

The house's plugs aren't grounded. Will this affect the efficacy of a
surge protector?
Is the computer at risk or just the AC adapter?

The best information on surges and surge protection I have seen is at:
http://omegaps.com/Lightning%20Guide_FINALpublishedversion_May051.pdf
- "How to protect your house and its contents from lightning: IEEE guide
for surge protection of equipment connected to AC 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 also:
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf
- "NIST recommended practice guide: Surges Happen!: how to protect the
appliances in your home" published by the US National Institute of
Standards and Technology in 2001

The IEEE guide is aimed at those with some technical background. The
NIST guide is aimed at the unwashed masses.

Myth purveyors will claim that a surge protector will absorb energy.
Energy that could not be stopped even by three miles of sky.
Protectors don't stop or absorb surges (except where myths are
promoted).

The IEEE guide explains plug-in suppressors work by CLAMPING the voltage
on all wires (signal and power) to the common ground at the suppressor.
Plug-in suppressors do not work primarily by earthing (or stopping or
absorbing). The guide explains earthing occurs elsewhere. (Read the
guide starting pdf page 40).
In the US, UL requires plug-in suppressors have MOVs from H-G, N-G, H-N.

Note that all interconnected equipment needs to be connected to the same
plug-in suppressor, or interconnecting wires need to go through the
suppressor. External connections, like phone, also need to go through
the suppressor. Connecting all wiring through the suppressor prevents
damaging voltages between power and signal wires. These multiport
suppressors are described in both guides.

A protector is nothing more than a connecting device to protection.
Protection is earth ground - where energy is absorbed.

w_ has a religious belief (immune from challenge) that surge protection
must use earthing. Thus in his view plug-in suppressors (which are not
well earthed) can not possibly work. As the IEEE guide explains, plug-in
suppressors do not work primarily by earthing.

Chances are the only earthing
(if it still exists) was to a cold water pipe. That earthing is no
longer sufficient even for human safety.

Complete nonsense. Water pipes (10 ft or more buried metal) have had to
be used as an earthing electrode in the US for a very long time.

For transistor safety, one
'whole house' protector connected to that upgraded earthing means
massive transistor protection.

A service panel suppressor is a good idea but then you also need a short
connecting wire from phone and cable entry protectors to the earthing
wire at the power service.

The house is likely rented which probably makes a power service panel
suppressor impractical.

Every incoming utility must enter at a same location to also make
that short earthing connection. For example, the phone line has a
'whole house' protector installed for free by the telco. But that
protector, also, is only as effective as its earth ground. Even the
cable must be earthed to that same electrode before entering the
building.

The cable and phone building entry protectors must connect with a
*short* wire to the earth electrode wire at the power service. A short
wire keeps the potential at the power and phone and cable ‘grounds’ the
same. In the IEEE example the ‘ground’ wire from the cable entry
protector is too long. That allows 10,000V to develop between the cable
and power wires. The IEEE guide says in that case "the only effective
way of protecting the equipment is to use a multiport protector." The
IEEE guide says even 10 foot connecting wire is too long (pdf page 38).

Francois Martzloff, the NIST guru on surges and author of the NIST
guide, has written "the impedance of the grounding system to `true
earth' is far less important than the integrity of the bonding of the
various parts of the grounding system."

According to NIST guide, US insurance information indicates equipment
most frequently damaged by lightning is
computers with a modem connection
TVs, VCRs and similar equipment (presumably with cable TV
connections).
All can be damaged by high voltages between power and signal wires.

Cable is protected without a protector. No reason for a
cable protector. Cable is earthed directly with no protector.

No reason for a protector? The IEEE guide notes that the voltage between
cable center conductor and sheath is limited by the breakdown of
F-connectors which is typically 2-4,000V. The guide notes that connected
equipment can be damaged at those voltages. Plug-in suppressors are
likely to clamp the voltage to a safe level.

Far more useful on 'that' unreliable wiring is to
replace selective circuit breakers with Arc fault breakers or GFCI
breakers.

If the wiring to the outlets does not have a ground, in the US equipment
with a ground prong on the power cord can be plugged into a GFCI outlet
or outlet that is protected by a GFCI. (The outlet needs to be marked
“No equipment ground”)

The best solution is if the computer can be moved to where there is a
grounded outlet. Using a plug-in suppressor without a grounded outlet is
not a great idea. Particularly if the equipment plugs have ground pins
there is not a great solution.

If the plugs are all 2 prong, I would probably use a plug–in suppressor.

A plug-in suppressor provides protection without a ground wire, but as
the IEEE guide shows, the ground potential can be shifted when the
suppressor works. It could also shift the ground potential if the MOVs
get ‘leaky’ if hit with many surges.

--
bud--

 

[Eeyore]

bud-- wrote:

w_tom wrote:
On Sep 22, 1:37 pm, David Schwartz <david...@gmail.com> wrote:

My son just moved into an older house near his college. We're told
that the electricity isn't entirely reliable and that he should use a
surge protector.

As others have noted, the problem may be surges or may be other power
problems. How common are lightning storms?

Indeed. The house wiring itself won't cause any surges.

From what I've heard the OP would be wise to check that the neutral isn't
'floating' though (assuming this is in the USA with the '2 phase' 240V supply).

Graham

 

[w_tom]

So what does the typically destructive surge seek? Earth ground.
Why must those earthing wires be so short? Well let's finish the
math. An AC wall receptacle is maybe 50 feet from the breaker box.
IOW it is maybe 0.2 ohms resistance. But the same wire is something
like 130 ohms impedance to the surge. What happens when a power strip
protector attempts to earth a trivial 100 amp surge via neutral wire?
13.000 volts difference. Will a surge use the 13,000 volt wire to
obtain earth? Of course not. It will also find other path to earth
via furniture, wall paint, baseboard heater, etc. The AC receptacle
ground is safety ground. But the destructive surge, if permitted at
the appliance, will find every path to earth - destructively.

The effective protector earths before that surge gets anywhere near
to appliances.

Your MOVs protectors do protect from the type of surge as exampled.
Do appreciate that it is not the type of surge that typically causes
damage. Surge that damaged electronics seeks earth ground. Its
energy must be dissipated somewhere. If not dissipated in earth, then
it dissipates destructively via household appliances in a path to
earth. If the MOV protector is grossly undersized as is common with
many plug-in protectors, then even these scary pictures can result:
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
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING%20SURGE%20SUPPRESSOR%20FIRES.doc

I appreciate the spirit of your reply. But you have completely
ignored some critical facts. Typically destructive surge seeks earth
ground. It may be completely ignored by your three MOV protector. Or
your three MOV protector may even give the surge more paths to find
earth, destructively, via adjacent appliances.

The surge you have discussed is typically made irrelevant by
protection already inside appliances. Anything that a power cord
protector might accomplish is already inside appliances. What can
overwhelm protection inside appliances? A type of surge that seeks
earth ground. We earth this typically destructive surge before it can
enter the building - and with only one properly sized protector. Then
massive energy of this far more destructive surge is dissipated in
earth - does not find destructive paths to earth via household
appliances.

What provided the protection? What dissipates surge energy? Does
that silly little MOV absorb such surges? Of course not. Surge energy
must dissipate somewhere. Earth is where surge energy is dissipated.
No earth ground means no effective protection from a type of surge
that typically cause appliance damage.

Appreciate that I have understood earthing for probably longer than
you have existed. You are even confusing low resistance earthing with
low impedance. Appreciate why a connection to earth ground must be
'less than 10 feet' - and other critical factors. If you don't
understand those numbers, then you have not yet learned the many
functions performed by earthing.

Of course this is well beyond what the OP was asking. Chances are
the building is so old as to not even have any earthing - a major
human safety problem as well as making a surge protector completely
ineffective.

On Sep 24, 12:54 am, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com>
wrote:

You don't have any clue what your talking about? Really, be honest!

The earth ground is only there for a direct ground reference and a low
resistance path to ground.

The problem with neutral and hot is that if they are wired incorrectly they
can easily kill someone. By having a direct reference to ground you can
eliminate this if it is used properly. It also supplies a lower resistance
to ground than the neutral(atleast as far as I have seen in my own house).

But in any case an earth ground an a neutral are identical in most cases
except for some small potential difference(atleast they should be in any
properly wired home).

I suggest you read up on

http://en.wikipedia.org/wiki/Ground_and_neutral

As far as surges go, you have essentially varistors that provide a very low
resistance path for a high voltage spike. This essentially takes out the
load after the varistor preventing(hopefully) most of the current from going
through the load.

For example, if you have

Hot -------+---- Load---+
| |
Varistor |
| |
Neutral ---+------------+

And if a large voltage spike occurs then the varistor acts somewhat as a
short essentially resulting in a short from hot to neutral and therefor
essentially dissconnecting the load from the mains. (atleast in theory it
would do that)

This has nothing to do with ground and you could even tie the varistor from
ground to netural(although it would not work if the ground was cut).

The varistor only stops surges though and doesn't protect in other others.
If the varistor breaks then so do the surge protection.

In any case "surge" protection doesn't need ground as netural is suppose to
be approximately equivilent to ground. The reason for "earth ground" in a
plug is for safety reasons and not surge protection.

Its a fact that neutral must also exist to complete the circuit so you can
always get surge protection... its also true that simple surge protectors
are not all that great. Using a simple MOV doesn't protect the load all that
great but its better than nothing and can't hurt.

So if the OP is only concerned with surge protection then he can do that by
buying good surge protectors... having earth ground isn't going to have any
effect except it could potentially make the surge protector a little better
if it was designed to use it. Maybe it could use a something like

+ -----+
/ \
MOV1 MOV2
/ \
- -+--MOV3-+--GND

Where if the ground was hooked up properly then you'll have better surge
protection... but there are better methods.

The extra earth on plugs is only for safety

 

[Jon Slaughter]

"w_tom" <w_tom1@usa.net> wrote in message
news:1190653812.895762.291430@19g2000hsx.googlegroups.com...

So what does the typically destructive surge seek? Earth ground.
Why must those earthing wires be so short? Well let's finish the
math. An AC wall receptacle is maybe 50 feet from the breaker box.
IOW it is maybe 0.2 ohms resistance. But the same wire is something
like 130 ohms impedance to the surge. What happens when a power strip
protector attempts to earth a trivial 100 amp surge via neutral wire?
13.000 volts difference. Will a surge use the 13,000 volt wire to
obtain earth? Of course not. It will also find other path to earth
via furniture, wall paint, baseboard heater, etc. The AC receptacle
ground is safety ground. But the destructive surge, if permitted at
the appliance, will find every path to earth - destructively.

The effective protector earths before that surge gets anywhere near
to appliances.

Your MOVs protectors do protect from the type of surge as exampled.
Do appreciate that it is not the type of surge that typically causes
damage. Surge that damaged electronics seeks earth ground. Its
energy must be dissipated somewhere. If not dissipated in earth, then
it dissipates destructively via household appliances in a path to
earth. If the MOV protector is grossly undersized as is common with
many plug-in protectors, then even these scary pictures can result:
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
http://tinyurl.com/3x73ol or
http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING%20SURGE%20SUPPRESSOR%20FIRES.doc

I appreciate the spirit of your reply. But you have completely
ignored some critical facts. Typically destructive surge seeks earth
ground. It may be completely ignored by your three MOV protector. Or
your three MOV protector may even give the surge more paths to find
earth, destructively, via adjacent appliances.

The surge you have discussed is typically made irrelevant by
protection already inside appliances. Anything that a power cord
protector might accomplish is already inside appliances. What can
overwhelm protection inside appliances? A type of surge that seeks
earth ground. We earth this typically destructive surge before it can
enter the building - and with only one properly sized protector. Then
massive energy of this far more destructive surge is dissipated in
earth - does not find destructive paths to earth via household
appliances.

What provided the protection? What dissipates surge energy? Does
that silly little MOV absorb such surges? Of course not. Surge energy
must dissipate somewhere. Earth is where surge energy is dissipated.
No earth ground means no effective protection from a type of surge
that typically cause appliance damage.

Appreciate that I have understood earthing for probably longer than
you have existed. You are even confusing low resistance earthing with
low impedance. Appreciate why a connection to earth ground must be
'less than 10 feet' - and other critical factors. If you don't
understand those numbers, then you have not yet learned the many
functions performed by earthing.

Of course this is well beyond what the OP was asking. Chances are
the building is so old as to not even have any earthing - a major
human safety problem as well as making a surge protector completely
ineffective.

I guess your the god of earth ground? Please... nots not get into some silly
fight over such an issue. I believe you are confusing safety with surge
protection. Surge protectors are not decides with saftey in mind but only to
protect the equipment involved to some degree.

I agree that safety is an issue and I agree its best to have earth ground.
Hell, maybe they would put a piece of rebar driven into the ground where
every recepticle is along with some type of external surge protection for
the whole house? But the fact of the matter is that is that many devices
use only hot and netural without any earth ground even whe its available(go
look at your toster and any small appliance).

In any case my point is that surge protectors themselfs do not need earth
ground. I never said it was a good idea not to have them but you claimed
they are completely ineffective without earth ground and this is simply not
the case. They do exactly what they were designed to do with out any earth
ground... infact if you open one up, at least in a cheap one, you will not
see the surge protection circuitry use earth ground at all.

The only thing I really disagree with you on is that surge protectors, and
here I'm implicitly refering to the common ones that the average person can
buy, do not need earth ground to protect against your average surge and
minimize damage to the device connected. It greatly minimizes the damage to
devices connected compared to not having anything at all(Even if you have
earth ground).

Is it the ultimate solution? Can you stop all surges and prevent all
possible saftey hazzards? No. But you can increase your chances to device
failure by 1000x(I'm just making that number up but seems resonable) by
adding even a cheap surge protector(a simple mov). Of course even that
introduces some saftey issues as you have proven by your links... MOV's are
perfect and if they short out then you can have a serious saftey problem.

Anyways...

 

[Eeyore]

w_tom wrote:

So what does the typically destructive surge seek?

What SURGE ?

A voltage transient across live and neutral 'seeks' nothing.

There seems to be some huge myths about 'surges'.

Graham

 

[w_tom]

On Sep 24, 2:11 pm, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com> wrote:

The only thing I really disagree with you on is that surge protectors, and
here I'm implicitly refering to the common ones that the average person can
buy, do not need earth ground to protect against your average surge and
minimize damage to the device connected. It greatly minimizes the damage to
devices connected compared to not having anything at all(Even if you have
earth ground).

You have assumed the only surge protector available to a layman is
power strip (plug-in) type. A layman must buy multiple plug-in
protectors sold by less responsible companies such as Tripplite,
Belkin, APC, Monster Cable, etc. for much more money. Or a layman can
purchase one effective protector sold by well respected companies.
Names understood by any guy who visit electrical supply departments
even in Lowes or Home Depot. Effective protector with a dedicated
earth ground is sold to layman by GE, Siemens, Cutler-Hammer,
Intermatic, Leviton, Square D and others.

An effective protector costs tens (maybe 100) times less money per
protected appliance. That 'so expensive' plug-in protector can even
contribute to damage of an adjacent appliance. No earth ground means
it must earth that surge somewhere. Published is this very first
conclusion in one 1996 IEEE paper:

Conclusion:
1) Quantitative measurements in the Upside-Down house clearly
show objectionable difference in reference voltages. These occur
even when or perhaps because, surge protective devices are
present at the point of connection of appliances.

Which one of us traced a surge destructively through a plug-in
protector; earthed that surge, destructively, through adjacent
computers. BTW, that plug-in protector did what its numerical
specifications claim. I and this IEEE author witnessed the same
problem.

Again you have assumed only one kind of surge - the one that is not
typically destructive. Again, you are ignoring what the typically
destructive surge seeks - earth ground. Again, you are ignoring wire
impedance - or why that earthing connection must be so short. Again,
where is the surge energy dissipated?

What happens if that plug-in protector grounds a surge on neutral
wire? A transient is then induced on all other adjacent wires - more
transients inside a building. Where is the protection? Just another
reason why the plug-in solution is ineffective.

Nothing new here. What is required for surge protection was well
proven even 80 years ago. The principles are based in what Ben
Franklin demonstrated in 1752. Protection without earthing was not
effective. Ham radio operators would even disconnect antenna leads,
put that connector inside a mason jar, and still suffer damage. When
did the damage stop? When the antenna was earthed. Why? Effective
surge protection is always about earthing surges.

Does your telco install plug-in protectors adjacent to their $multi-
million switching computers? Of course not. Your telco does not
waste money on ineffective and grossly expensive devices. Your telco
installs protectors to be more effective AND cost less money. To make
protection even better, your telco installs a better earthing system.
Better earthing makes better protectors.

Jon. You claim earthing is not essential? Why is earthing THE most
critical part of every protection system including your telco's surge
protection? They don't shutdown for every thunderstorm. They cannot
suffer surge damage. Their computer is connected to overhead wires
all over town. Each thunderstorm may result in 100 surges. Why does
the telco not suffer damage? Their protectors connect as short as
possible to earth ground. Tto make that protection even better, a
telco wants that protector up to 50 meters distant from electronics.
Appreciate the separation that also makes a protector more effective.

Short to earth ground and separated from electronics means better
protection. How curious. Homeowners can obtain same protection in
one 'whole house' protector with proper earthing. What follows are
example after example; what both professionals and experience teach.

In literally every IEEE paper on surge protection, what is always
required? Earth ground. How did van der Laan and Deursen correct
surge damage in a nuclear hardened, Norwegian, maritime radio station
in their 1998 IEEE paper? They fixed the earthing. They corrected
how protectors were earthed.

How did another construct a radio station so as to not suffer damage
from direct lightning strikes?
http://scott-inc.com/html/ufer.htm

The NIST defines what a protector does on page 6 (Adobe page 8 of
24) .
http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf

You cannot really suppress a surge altogether, nor
"arrest" it. What these protective devices do is
neither suppress nor arrest a surge, but simply
divert it to ground, where it can do no harm.

Another professional with decades of experience describes
protection:
http://www.harvardrepeater.org/news/lightning.html

Well I assert, from personal and broadcast experience spanning
30 years, that you can design a system that will handle *direct
lightning strikes* on a routine basis. It takes some planning and
careful layout, but it's not hard, nor is it overly expensive. At
WXIA-TV, my other job, we take direct lightning strikes nearly
every time there's a thunderstorm. Our downtime from such
strikes is almost non-existant. The last time we went down from a
strike, it was due to a strike on the power company's lines
knocking *them* out, ...
Since my disasterous strike, I've been campaigning vigorously
to educate amateurs that you *can* avoid damage from direct
strikes. The belief that there's no protection from direct strike
damage is *myth*. ...
The keys to effective lightning protection are surprisingly simple,
and surprisingly less than obvious. Of course you *must* have a
single point ground system that eliminates all ground loops. And
you must present a low *impedance* path for the energy to go.
That's most generally a low *inductance* path rather than just a
low ohm DC path.

Jon - how many decades ago were you building these systems; learning
from experience? How many decades ago were you tracing surge damage
by even replacing semiconductors to make electronics completely
functional? You claim we all have been wrong all this time? You did
not even know about wire impedance - why the earthing wire must be so
short, no sharp bends, separated from other wires (which is why the
ground or neutral wire inside Romex is not sufficient for earthing),
no splices, not inside metallic conduit, etc. Why do we know about
things so important for earthing? Do you even know why that wire must
not be inside metallic conduit?

How many semesters did you take in Electromagnetic Wave Theory?

Jon. Again I appreciate your spirit. But your analysis completely
ignores fundamental electrical concepts. Do you know why wire inside
conduit makes a bad surge conductor? You did not even answer this
question - where does surge energy get dissipated? If not earth, then
where?

You have recommended protection from one type of transient that is
made irrelevant by standard electronic designs. Where is surge
energy dissipated? Earth ground is where that energy is dissipated
without damage.

How did Orange Country stop surge damage to their emergency response
facilities? Did they install plug-in protectors? Of course not.
Orange County fixed their earthing systems - nothing more:
http://www.psihq.com/AllCopper.htm

Defined was a 'whole house' protector - a *secondary* protection
system. What is the center of that system? Building earth ground.
What is *primary* protection? A homeowner should also inspect the
essential component of their *primary* protection system:
http://www.tvtower.com/fpl.html

Where surge damage is not acceptable, earthing is the one component
always required for effective protection. A protector is only as
effective as its earth ground. Some protection systems don't even
require a protector - but always require earthing. How many examples
of professionally installed solutions were provided? 15?

Of course, none of this addresses human safety problems created by
unreliable wiring - an internal problem. Earthing is also important
for human safety reasons as well as for transistor safety. This is
about earthing to avoid externally source problems. One properly
earthed protector is - by far - the most effective solution and the
best solution per dollar. It is the only solution for a house with
two wire receptacles.

Too many older homes are missing an earthing system - let alone one
that both meets and exceeds post 1990 National Electrical Code
requirements. We are not discussing 100% protection. Discussed is
protection that is well over 90% effective. Earthing both for
transistor safety and for human safety. Even those 'scary pictures'
demonstrate the pathetic nature of plug-in protectors - near zero
proteciton. Don't agree? Then where does that plug-in protector's
specs even claim protection from the type of surge that does damage?
It does not. Those cheap plug-in protectors may even earth surges,
destructively, through adjacent electronics. No earth ground means no
effective protection.

Even worse, those cheap protectors cost tens of times more money per
protected appliance - are more expensive as well as ineffective. The
effective protector costs about $1 per protected appliance. The only
effective protector is the one that can earth typically destructive
surges.

How many of your protector designs have been tested by direct
lightning strikes? Well, show us how fifteen times over how all this
is wrong. Explain the importance of wire impedance. Explain where
surge energy is dissipated. Explain how to a plug-in protector stop
surges from seeking eath ground. Explain why the plug-in manufacturer
does not even claim protection. Explain why so many professionals are
wrong. Instead, a protector is only as effective as its earth ground.

I appreciate what you have posted. But it is what you don't know
that has led you to erroneous conclusions. One glaringly obvious
problem. Where is the surge energy dissipated? Another obvious
problem. Why do locating that cannot suffer damage not use the
protectors you have recommended?