AC Power Surge Protection?

[Gareth Magennis]

"Phil Allison" wrote in message
news:85f11b0e-85bd-4d2c-8db0-c6bbee864ad3@googlegroups.com...

bud-- wrote:

As explained in the IEEE surge guide
(starting page 30) plug-in protectors work primarily by limiting the
voltage from each wire to the ground at the protector.

** Connecting MOVs to ground like that in a *plug-in device* is prohibited
on safety grounds under EU and similar regulations as followed in most
230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in
excess of the maximum permitted, which is only a milliamp or so for most
categories of appliances.

The only components that may be so connected are agency approved " Y caps "
with values like 4.7nF - while MOVs and " X caps" always go across the
line.



.... Phil



Slightly OT but .....
In the UK you can buy "surge protected" multi outlet extensions like this:
http://www.amazon.co.uk/Sivitec-Switched-Extension-Protection-Indicator/dp/B00DVHK7IY/ref=sr_1_1?ie=UTF8&qid=1432969032&sr=8-1&keywords=4+gang+surge+protection

Problem is, these can't be tested with a typical PAT Tester, as they fail
the test every time, being as there is circuitry between live and ground.



Gareth.

 

[Phil Allison]

Gareth Magennis wrote:

"Phil Allison" wrote in message
news:85f11b0e-85bd-4d2c-8db0-c6bbee864ad3@googlegroups.com...

bud-- wrote:


As explained in the IEEE surge guide
(starting page 30) plug-in protectors work primarily by limiting the
voltage from each wire to the ground at the protector.

** Connecting MOVs to ground like that in a *plug-in device* is prohibited
on safety grounds under EU and similar regulations as followed in most
230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in
excess of the maximum permitted, which is only a milliamp or so for most
categories of appliances.

The only components that may be so connected are agency approved " Y caps "
with values like 4.7nF - while MOVs and " X caps" always go across the
line.


In the UK you can buy "surge protected" multi outlet extensions like this:
http://www.amazon.co.uk/Sivitec-Switched-Extension-Protection-Indicator/dp/B00DVHK7IY/ref=sr_1_1?ie=UTF8&qid=1432969032&sr=8-1&keywords=4+gang+surge+protection


Problem is, these can't be tested with a typical PAT Tester, as they fail
the test every time, being as there is circuitry between live and ground.

** Really? You read this somewhere on the net, right?

I bet they CAN be tested, passing all the tests is the issue.

FYI:

A customer, who runs a hire business, brought in his "Megger 4DV" PAT tester recently for a check over - so I got to see exactly what it did and how.

Some tests involved normal AC power being applied to the device, others used high voltage DC and another low voltage AC at high current to check earth conductor resistance.

AC leakage current and insulation resistance are the main things checked - the pass /fail threshold was user adjustable to suit the type of appliance under test. Class 1 and class 2 ( double insulated ) appliances follow different rules.

The operator is also expected to carry out a thorough visual inspection too, so needs to be familiar with electrical appliance safety.

If a new product failed one of the tests, that would be VERY alarming and should be reported to the supplier immediately.



.... Phil

 

[Gareth Magennis]

"Phil Allison" wrote in message
news:408a078a-4d5b-4474-aad2-dfd233176312@googlegroups.com...

Gareth Magennis wrote:

"Phil Allison" wrote in message
news:85f11b0e-85bd-4d2c-8db0-c6bbee864ad3@googlegroups.com...

bud-- wrote:


As explained in the IEEE surge guide
(starting page 30) plug-in protectors work primarily by limiting the
voltage from each wire to the ground at the protector.

** Connecting MOVs to ground like that in a *plug-in device* is prohibited
on safety grounds under EU and similar regulations as followed in most
230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in
excess of the maximum permitted, which is only a milliamp or so for most
categories of appliances.

The only components that may be so connected are agency approved " Y caps
"
with values like 4.7nF - while MOVs and " X caps" always go across the
line.


In the UK you can buy "surge protected" multi outlet extensions like this:
http://www.amazon.co.uk/Sivitec-Switched-Extension-Protection-Indicator/dp/B00DVHK7IY/ref=sr_1_1?ie=UTF8&qid=1432969032&sr=8-1&keywords=4+gang+surge+protection


Problem is, these can't be tested with a typical PAT Tester, as they fail
the test every time, being as there is circuitry between live and ground.

** Really? You read this somewhere on the net, right?





No, I have a PAT Tester and PAT Test all the sound and lighting equipment
for a music festival.

I was told by an electrician that you have to test these as Class 2, and put
a sticker on them to say so.


Gareth.

 

[bud--]

On 5/29/2015 9:06 PM, Phil Allison wrote:

bud-- wrote:


As explained in the IEEE surge guide
(starting page 30) plug-in protectors work primarily by limiting the
voltage from each wire to the ground at the protector.

** Connecting MOVs to ground like that in a *plug-in device* is prohibited on safety grounds under EU and similar regulations as followed in most 230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in excess of the maximum permitted, which is only a milliamp or so for most categories of appliances.

The only components that may be so connected are agency approved " Y caps " with values like 4.7nF - while MOVs and " X caps" always go across the line.

... Phil

I think the US-UL permitted leakage for "appliances" is 0.5mA (which of
course is at 120V).

Standard practice in the US for plug-in protectors is MOVs from H-N,
H-G, N-G. And if signal wires go through the protector, they are limited
to ground also.

One of the reasons the energy at a MOV in a protector is so low (US) is
that at about 6kV there is arc-over between service panel busbars and
the enclosure. This appears to be an intentional feature. (The voltage
across the established arc is hundreds of volts. Since the enclosure is
connected to the earthing system that dumps most of the surge energy to
earth. And a required N-G bond at the service limits the N surge voltage.)

A significant (and likely major) cause of surge damage to equipment is
high voltage between power and signal wires. If MOVs are only connected
H-N and there is a large surge the voltage drop on H & N will likely
increase the voltage between power and signal wires (6kV at the service
would result in about 2kV from the H & N to the 'ground' reference at
the service panel). It then would be inadvisable to use plug-in
protectors on equipment that has both power and signal wires.

The normal failure mode for MOVs is after sufficient energy hits they
start to conduct at lower voltages, eventually conduct at 'normal'
voltages, and go into thermal runaway. Thermal disconnects then
operate(at least in the US). I would think a H-N MOV with 1mA leakage
@230V would be near thermal runaway.

I don't know how surge protection is done down-under. It works here.
Some features here may be from the relatively high exposure to
thunderstorms in parts of the country. They are uncommon or nonexistent
in many parts of the globe.

 

[Phil Allison]

Gareth Magennis wrote:

"Phil Allison"

** Connecting MOVs to ground like that in a *plug-in device* is prohibited
on safety grounds under EU and similar regulations as followed in most
230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in
excess of the maximum permitted, which is only a milliamp or so for most
categories of appliances.

The only components that may be so connected are agency approved " Y caps
"
with values like 4.7nF - while MOVs and " X caps" always go across the
line.


In the UK you can buy "surge protected" multi outlet extensions like this:
http://www.amazon.co.uk/Sivitec-Switched-Extension-Protection-Indicator/dp/B00DVHK7IY/ref=sr_1_1?ie=UTF8&qid=1432969032&sr=8-1&keywords=4+gang+surge+protection


Problem is, these can't be tested with a typical PAT Tester, as they fail
the test every time, being as there is circuitry between live and ground.


** Really? You read this somewhere on the net, right?


No, I have a PAT Tester and PAT Test all the sound and lighting equipment
for a music festival.

I was told by an electrician that you have to test these as Class 2, and put
a sticker on them to say so.

** That is completely insane crap.

He must have been using illegal drugs to say such a thing and you are nuts to believe it.




.... Phil

 

[Phil Allison]

bud-- wrote:
Phil Allison wrote:

** Connecting MOVs to ground like that in a *plug-in device* is prohibited on safety grounds under EU and similar regulations as followed in most 230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in excess of the maximum permitted, which is only a milliamp or so for most categories of appliances.

The only components that may be so connected are agency approved " Y caps " with values like 4.7nF - while MOVs and " X caps" always go across the line.



Standard practice in the US for plug-in protectors is MOVs from H-N,
H-G, N-G.

** I really doubt using three MOVs like that is *normal* practice - certainly one never sees it in entertainment electronics or test gear, whether made in the USA or elsewhere.

The normal failure mode for MOVs is after sufficient energy hits they
start to conduct at lower voltages, eventually conduct at 'normal'
voltages, and go into thermal runaway.

** The fact that MOVs deteriorate means it is hazardous to have them wired from active to safety ground. Same argument goes for regular metallised film capacitors which also deteriorate when exposed to AC supply voltages - then explode.

I would think a H-N MOV with 1mA leakage
@230V would be near thermal runaway.

** Takes at least 10mA to get a typical MOV device hot.



..... Phil

 

[Phil Allison]

bud-- wrote:

On 5/31/2015 1:14 AM, Phil Allison wrote:
bud-- wrote:
Phil Allison wrote:

** Connecting MOVs to ground like that in a *plug-in device* is prohibited on safety grounds under EU and similar regulations as followed in most 230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in excess of the maximum permitted, which is only a milliamp or so for most categories of appliances.

The only components that may be so connected are agency approved " Y caps " with values like 4.7nF - while MOVs and " X caps" always go across the line.



Standard practice in the US for plug-in protectors is MOVs from H-N,
H-G, N-G.


** I really doubt using three MOVs like that is *normal* practice - certainly one never sees it in entertainment electronics or test gear, whether made in the USA or elsewhere.

Entertainment electronics may have some surge protection but is not
intended to protect against major surges.

** Nor are an plug-in surge protectors.

You are bullshitting wildly.

As can be seen from the IEEE surge guide, 3 MOVs is absolutely standard
practice in the US.

** Really - you must send me a copy.

Yawnnnnn....

Because of the additional risks added by having only H-N protection in
plug-in protectors

** There is no risk that derives from the device itself - until you add MOVs to ground. You really need to pay attenion to the context.


(as in my last post) I suspect 3 MOVs is common
> practice elsewhere,

** What you "suspect" is on no value, at all, to anyone.

> H-N only protectors can increase risk, not reduce it.

** Insane crap.

> Gareth does not know what is connected H-G.

** Gareth is an even bigger bullshitter than you.

All the packaging protectors come in that I have seen indicate what the
protection is (H-N, H-G, N-G). I suspect it would elsewhere. I am not
interested in looking.

** ROTFL.

The normal failure mode for MOVs is after sufficient energy hits they
start to conduct at lower voltages, eventually conduct at 'normal'
voltages, and go into thermal runaway.


** The fact that MOVs deteriorate means it is hazardous to have them wired from active to safety ground. Same argument goes for regular metallised film capacitors which also deteriorate when exposed to AC supply voltages - then explode.


In the US the likely maximum surge energy at a MOV in a plug-in
protector is a tiny 35J, and that includes for the largest probable
power line surge (as in my 1st post). The simplest UL listed protector
here will have a joule rating far above that.

** Another one of you wild suspicions ?

You could also say it is hazardous to have leakage and fault currents on
the safety ground.

** It is.

You totally fail to see what the safety issue is.

You have no understanding of why no ordinary or class X film caps of any value can be wired from line to safety ground, ONLY special class Y types are permitted in restricted values. True in the USA, the EU and elsewhere.




... Phil

 

[Phil Allison]

Chris Jones wrote:

At least some testers measure the insulation resistance (between
live/neutral and earth) at either 500VDC or 250VDC. The 250V setting is
labelled "MOV".
This document explains the testing process:

http://uk.megger.com/getmedia/a5f14a4f-e742-4e85-b7de-db02f5f9a533/PAT-Testing-surge-protected-equipment_AN_en_V01.pdf/

** That note is dated *2014* and admits that PAT testers without a 250VDC setting cannot distinguish devices with MOVs to ground from faulty devices.
This is not an acceptable situation.

IIRC, the "Megger 4DV" that I saw had no such setting.

The note from Megger on testing these surge protectors above also seems
to imply that connecting MOVs between live and earth is a common
arrangement,

** So common that they noticed it only last year !!!

Yawnnnnnnnnnnnnn.....

Other pages seem to suggest that at least in some cases/countries, MOVs
are connected directly from live to earth.

** Sure - in the USA, but only in some surge protectors.

Whilst I would agree with Phil that a used MOV is
likely to be so leaky as to result in unacceptable current flowing from
live to earth, I'm not sure that many of the appliance standards would
catch this,

** No need to "catch" it, the fitting of MOVs to ground inside a plug-in appliance is simply prohibited.

The standard 500V DC leakage test would indicate the existence of a MOV wired to ground - if eyeballs were not able to.



.... Phil

 

[Chris Jones]

On 30/05/2015 16:59, Gareth Magennis wrote:

"Phil Allison" wrote in message
news:85f11b0e-85bd-4d2c-8db0-c6bbee864ad3@googlegroups.com...

bud-- wrote:


As explained in the IEEE surge guide
(starting page 30) plug-in protectors work primarily by limiting the
voltage from each wire to the ground at the protector.

** Connecting MOVs to ground like that in a *plug-in device* is
prohibited on safety grounds under EU and similar regulations as
followed in most 230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in
excess of the maximum permitted, which is only a milliamp or so for most
categories of appliances.

The only components that may be so connected are agency approved " Y
caps " with values like 4.7nF - while MOVs and " X caps" always go
across the line.



... Phil



Slightly OT but .....
In the UK you can buy "surge protected" multi outlet extensions like this:
http://www.amazon.co.uk/Sivitec-Switched-Extension-Protection-Indicator/dp/B00DVHK7IY/ref=sr_1_1?ie=UTF8&qid=1432969032&sr=8-1&keywords=4+gang+surge+protection


Problem is, these can't be tested with a typical PAT Tester, as they
fail the test every time, being as there is circuitry between live and
ground.



Gareth.

At least some testers measure the insulation resistance (between
live/neutral and earth) at either 500VDC or 250VDC. The 250V setting is
labelled "MOV". This document explains the testing process:
http://uk.megger.com/getmedia/a5f14a4f-e742-4e85-b7de-db02f5f9a533/PAT-Testing-surge-protected-equipment_AN_en_V01.pdf/

The note from Megger on testing these surge protectors above also seems
to imply that connecting MOVs between live and earth is a common
arrangement, however they show a gas discharge tube between the Earth
wire and the MOVs. It would be interesting to know if this is common and
if so, why and what are its ratings.

Other pages seem to suggest that at least in some cases/countries, MOVs
are connected directly from live to earth.
http://en.wikipedia.org/wiki/Power_strip#Surge_protection_and_filtering
http://www.racktronics.com.au/gallery.php
http://badcaps.net/forum/showthread.php?p=10176

I'm not sure whether this is a good thing, unless you know for sure that
your earth connections are all present and correct, and your RCD/ELCB is
present and working. Whilst I would agree with Phil that a used MOV is
likely to be so leaky as to result in unacceptable current flowing from
live to earth, I'm not sure that many of the appliance standards would
catch this, unless the sequence of tests (during product approval not
PAT) would first damage and later test the leakage of the MOV.

Chris

 

[bud--]

On 5/31/2015 1:14 AM, Phil Allison wrote:

bud-- wrote:
Phil Allison wrote:

** Connecting MOVs to ground like that in a *plug-in device* is prohibited on safety grounds under EU and similar regulations as followed in most 230/240 V places - like Australia where I am.

MOVs either have or can develop after some use leakage currents well in excess of the maximum permitted, which is only a milliamp or so for most categories of appliances.

The only components that may be so connected are agency approved " Y caps " with values like 4.7nF - while MOVs and " X caps" always go across the line.



Standard practice in the US for plug-in protectors is MOVs from H-N,
H-G, N-G.


** I really doubt using three MOVs like that is *normal* practice - certainly one never sees it in entertainment electronics or test gear, whether made in the USA or elsewhere.

Entertainment electronics may have some surge protection but is not
intended to protect against major surges.

As can be seen from the IEEE surge guide, 3 MOVs is absolutely standard
practice in the US.

Because of the additional risks added by having only H-N protection in
plug-in protectors (as in my last post) I suspect 3 MOVs is common
practice elsewhere, H-N only protectors can increase risk, not reduce
it. Gareth does not know what is connected H-G. You do not necessarily
know what the specific requirements are for plug-in protectors elsewhere.

All the packaging protectors come in that I have seen indicate what the
protection is (H-N, H-G, N-G). I suspect it would elsewhere. I am not
interested in looking.

The normal failure mode for MOVs is after sufficient energy hits they
start to conduct at lower voltages, eventually conduct at 'normal'
voltages, and go into thermal runaway.


** The fact that MOVs deteriorate means it is hazardous to have them wired from active to safety ground. Same argument goes for regular metallised film capacitors which also deteriorate when exposed to AC supply voltages - then explode.

In the US the likely maximum surge energy at a MOV in a plug-in
protector is a tiny 35J, and that includes for the largest probable
power line surge (as in my 1st post). The simplest UL listed protector
here will have a joule rating far above that.

The joule rating of a MOV is the single event energy that will put the
MOV at defined end of life (but still functional). Looking at MOV
ratings curves, if the MOV gets single hits that are far below that, the
cumulative rating is far above (like over 10x) the single event rating.
Failure is real unlikely. Coupled with high ratings, that is why some
companies can have protected equipment warranties.

The author of the NIST surge guide has written "in fact, the major
cause of [surge protector] failures is a temporary overvoltage, rather
than an unusually large surge." An example of temporary overvoltage
would be a high voltage distribution wire coming down on the 115/230V
secondary conductors.

You could also say it is hazardous to have leakage and fault currents on
the safety ground.

 

[bud--]

On 5/31/2015 7:53 AM, Chris Jones wrote:

however they show a gas discharge tube between the Earth
wire and the MOVs. It would be interesting to know if this is common and
if so, why and what are its ratings.

As a guess, the GDT prevents leakage Phil is worried about, and the MOV
prevents "follow-on" discharge through the GDT right after the surge is
over and normal power is present.

Whilst I would agree with Phil that a used MOV is
likely to be so leaky as to result in unacceptable current flowing from
live to earth,

As I responded to Phil, this is actually quite unlikely (at least in the
US).

I'm not sure that many of the appliance standards would
catch this, unless the sequence of tests (during product approval not
PAT) would first damage and later test the leakage of the MOV.

US-UL tests include a series of test surges, after which the device has
to be functional (in particular, it is not 'leaking').

Later tests may cause the device to fail, but it must fail safely.

 

[bud--]

On 5/31/2015 8:11 AM, Phil Allison wrote:

bud-- wrote:

As can be seen from the IEEE surge guide, 3 MOVs is absolutely standard
practice in the US.


** Really - you must send me a copy.

Yawnnnnn....

Link to the IEEE surge guide was in my first post. Excellent information
from a completely reliable source. If you read it you might learn something.

H-N only protectors can increase risk, not reduce it.

** Insane crap.

The problem I described, with 3 MOV protectors, is well know and in a
published research paper by the author of the NIST surge guide (guide is
also linked in my 1st post). Problems with using only a H-N MOV are
considerably greater. The fix in the paper was to run not just power
wires, but also signal wires through the protector with the voltage
limited from all wires to the ground at the protector (as also described
starting page 30 in the IEEE surge guide, which is linked-to in my 1st
post).

In the US the likely maximum surge energy at a MOV in a plug-in
protector is a tiny 35J, and that includes for the largest probable
power line surge (as in my 1st post). The simplest UL listed protector
here will have a joule rating far above that.

** Another one of you wild suspicions ?

Published research by the author of the NIST surge guide , who was the
US-NIST surge expert.

My information comes from the IEEE, the NIST, and published research.


Sometimes you post really interesting information.

Sometimes not.

This is one of the latter.

 

[Phil Allison]

bud-- wrote:

bud-- wrote:

As can be seen from the IEEE surge guide, 3 MOVs is absolutely standard
practice in the US.


** Really - you must send me a copy.

Yawnnnnn....

Link to the IEEE surge guide was in my first post. Excellent information
from a completely reliable source.

** Fraid it is neither.

Nothing more than a simplistic, broad overview with no examples of any commercial products.

It does NOT say what you claim.

H-N only protectors can increase risk, not reduce it.

** Insane crap.

The problem I described,

** Listen you pompous halfwit:

the ** SAFETY HAZARD ** I am referring to is severe electric shock delivered to the user of the device.

Have you no idea how that can happen with MOVs wired to ground in a plug in device? ??

Obviously not - since the IEEE etc docs you linked do not bother to mention it.

Do I really have to rub your stupid nose in it ?

Sometimes you post really interesting information.

** Not just sometimes.

And you still have NO damn clue about the electric shock hazard inherent in connecting a MOV, cap, resistor or any sort of load from the current carrying conductors to safety ground inside a plug-in device.



.... Phil

 

[whit3rd]

On Sunday, May 31, 2015 at 12:14:55 AM UTC-7, Phil Allison wrote:

bud-- wrote:
Phil Allison wrote:

** Connecting MOVs to ground like that in a *plug-in device* is prohibited on safety grounds under EU and similar regulations

Standard practice in the US for plug-in protectors is MOVs from H-N,
H-G, N-G.

** I really doubt using three MOVs like that is *normal* practice - certainly one never sees it in entertainment electronics or test gear, whether made in the USA or elsewhere.

It isn't acceptable for US medical devices, but it isn't unknown, either. It's always
combined with a fuse, where I've seen it.

 

[Cursitor Doom]

On Sun, 31 May 2015 23:50:30 -0700, Phil Allison wrote:

> Do I really have to rub your stupid nose in it ?

"I'm so sorry; he's from Barcelona."

 

[bud--]

On 6/1/2015 12:50 AM, Phil Allison wrote:

bud-- wrote:

bud-- wrote:

As can be seen from the IEEE surge guide, 3 MOVs is absolutely standard
practice in the US.


** Really - you must send me a copy.

Yawnnnnn....

Link to the IEEE surge guide was in my first post. Excellent information
from a completely reliable source.

** Fraid it is neither.

https://en.wikipedia.org/wiki/Institute_of_Electrical_and_Electronics_Engineers
The IEEE currently has 400,000 members.

The surge guide comes from the Surge Protection Devices Committee. That
is people who actually design surge protectors and protection schemes.
They also write standards for surge protection.

Nothing more than a simplistic, broad overview with no examples of any commercial products.

It does NOT say what you claim.

For anyone with minimal reading skills, it shows how surge protectors
are connected and how they work (at least in the US). Namely MOVs from
H-N, H-G, and N-G.

H-N only protectors can increase risk, not reduce it.

** Insane crap.

The problem I described,


** Listen you pompous halfwit:

So do I trust people who actually design surge protection and have done
basic research, all of whom support what I have written?

Or do I trust Phil, who is currently in troll mode?

....that's a tough one...

 

[Phil Allison]

bud the dope -- wrote:


( snip piles of irrelevant crap about the IEEE)


** Listen you pompous halfwit:

the ** SAFETY HAZARD ** I am referring to is severe electric shock delivered to the user of the device.

Have you no idea how that can happen with MOVs wired to ground in a plug in device? ??

Obviously not - since the IEEE etc docs you linked do not bother to mention it.

Do I really have to rub your stupid nose in it ?

And you still have NO damn clue about the electric shock hazard inherent in connecting a MOV, cap, resistor or any sort of load from the current carrying conductors to safety ground inside a plug-in device.

Obviously, you cannot answer these important points.

FYI:

The executive director of the IEEE is a guy I went to high school and university with - Jim Prendergast.

https://www.ieee.org/about/management_council.html?WT.mc_id=lp_ab_imc

Totally irrelevant, of course.


.... Phil

 

[Cydrome Leader]

Phil Allison <pallison49@gmail.com> wrote:

bud the dope -- wrote:


( snip piles of irrelevant crap about the IEEE)


** Listen you pompous halfwit:

the ** SAFETY HAZARD ** I am referring to is severe electric shock delivered to the user of the device.

Have you no idea how that can happen with MOVs wired to ground in a plug in device? ??

Obviously not - since the IEEE etc docs you linked do not bother to mention it.

Do I really have to rub your stupid nose in it ?

And you still have NO damn clue about the electric shock hazard inherent in connecting a MOV, cap, resistor or any sort of load from the current carrying conductors to safety ground inside a plug-in device.

Obviously, you cannot answer these important points.

FYI:

The executive director of the IEEE is a guy I went to high school and university with - Jim Prendergast.

https://www.ieee.org/about/management_council.html?WT.mc_id=lp_ab_imc

Totally irrelevant, of course.


... Phil

I have to agree with Phil here. The key here is plug-in device. This is
why "surge strips" or any sort of power strip with surge supression are
just pure trash.

when these devices are not on fire, and are able to shunt some sort of
surge, real or imagined into ground, you elevate the voltage on that
segment of the ground circuit. That destroys or interferes with all the
other equiment connected to that that ground.

Keep in mind lots of grounds aren't even really grounded, or grounded
properly, especially in homes, old homes or places with poorly done
electrical work. The end of the line is the worst place to try to stop a
surge.

I had to remove some walls in a new space office space and wiring we found
was appalling. Had to have the building engineer drop by to take a look
for himself. He was baffled as well. Disconneting the weird wiring even
resulted in one light switch causing the lights to just flicker instead
off turn off in the off position. It wasn't even a two way switch.

 

[bud--]

On 6/3/2015 9:40 AM, Cydrome Leader wrote:

I have to agree with Phil here. The key here is plug-in device. This is
why "surge strips" or any sort of power strip with surge supression are
just pure trash.

Experts at the IEEE and NIST say say they are effective. That is based
on research and experience.

Where is a source that agrees with you?

when these devices are not on fire, and are able to shunt some sort of
surge, real or imagined into ground, you elevate the voltage on that
segment of the ground circuit. That destroys or interferes with all the
other equiment connected to that that ground.

The IEEE surge guide clearly explains how plug-in protectors work. It is
not primarily by earthing the surge.

And as any competent manufacturer, along with the IEEE and NIST make
clear, and as I wrote in my 1st post, "if using a plug-in protector all
interconnected equipment needs to be connected to the same protector.
External connections, like coax also must go through the protector. As
explained in the IEEE surge guide (starting page 30) plug-in protectors
work primarily by limiting the voltage from each wire to the ground at
the protector. To do that all wires must go through the protector."

As I also pointed out, the amount of energy that has any reasonable
probability of being absorbed in a MOV at a plug-in protector is
asurprisingly small 35 joules, and in 13 of 15 test cases it was 1 joule
or less (US). That is based on research. The largest energy is actually
not for the largest surges. One reason the energy is so small is there
is arc-over at about 6kV from panel busbars to the enclosure - and the
established arc is hundreds of volts. That dumps most of the energy of a
large surge to earth, and limits the exposure in a house. The second
reason is a surge is a very short event. That means the current
components are relatively high frequency. That means the impedance of
the branch circuit is more important than the resistance. The result is
the amount of surge current is quite limited which means that the energy
is limited.

What I have written is based on surge guides from reliable sources which
I have linked to, and on published research.

On the other side are opinions by you and Phil.

Maybe if you figured out how they worked....

 

[Ralph Mowery]

"bud--" <null@void.com> wrote in message
news:556f987f$0$29478$c3e8da3$e074e489@news.astraweb.com...

On 6/3/2015 9:40 AM, Cydrome Leader wrote:

I have to agree with Phil here. The key here is plug-in device. This is
why "surge strips" or any sort of power strip with surge supression are
just pure trash.

Experts at the IEEE and NIST say say they are effective. That is based on
research and experience.

Personal experiance tells me they work. During a thunderstorm a
transformer let go that feed my house and three others. I had surge strips
on all the electronics that plug in the wall. Two of the strips and a MOV
on the stove were taken out. No other damage. Two of the other houses lost
their TV sets and some other things. Did not talk to the third house to see
if he lost anything or not.