A question for an EE - Surge protector joule ratings - how much is enough

[Rickster71]

I gave up on this website/forum after I felt i was receiving very little/poor help from some members ( TBH I felt westom wasn't giving me a direct yes/no answer

This site has 56,303 members.
Westom is ranked as one of the bottom five members out of over 56 thousand members.
Shouldn't that tell you something?

If you need any questions answered, jnutron was kind enough to offer to do that.
I suggest you PM jnutron.
That helps avoid one of the sites lowest ranked trolls.

 

[jneutron]

jn,

What about Line conditioners in Surge Protectors and stand alone Line Conditioners

That always depends on the specific devices, so you'd have to take it case by case.

and last question, is it safe to daisy chain one surge protector into another surge protector for the assumed benefit of doubling joule ratings ( i.e. 1500 joules in each bar x 2 = 3000 joule of protection) and line conditioning ( i.e. -30db of reduction in line noise from one and another -30db from the other protector = -60 db in total of noise reduction)

It is indeed safe to daisy chain from an electrical point of view. However, it is not a recommended practice. All the ele guys hate to make a Christmas tree out of cords and adapters. But I understand your question regarding the math, so I'll answer that directly.

If you purchase two SPD's with the same voltage rating, there will be a range of voltages that they will clamp at. And they will never be the same. The lower one will generally take the brunt of the hit, and the higher one may or may not see any current at all, depending on how loose the first MOV is clamp-wise.

If the one taking the brunt eventually fails, it will usually fail into a shorted condition, and pop either the unit's breaker/fuse, or the load panel at your house AC in location. If it fails by opening, then the second would be a belts and suspenders safety. But generally, you will be no better off by just buying two and plugging them together, you have no control over the coordination of the current paths.

The whole house one works with multiport branch spd's because it is in the 400 volt range, and the endpoint branch ones typically 330.

Line conditioners (filters) are generally not designed to work with other line conditioners. It may add benefits in terms of filtering as you describe, but I wouldn't count on it. Many filters stop the noise by sending it to ground or neutral, and having a second one do the same may not benefit.

I'd recommend one unit at a specific location, and a whole house at the load panel.

Thats pretty much all the questions I have on this topic which is just so poorly handled on the web so thanks a bunch for giving some insight

Your welcome. There are so many like w-dude out there, that actual engineers who do it for a living shy away because of the abuse they will get from the un-informed.

There is of course, misinformation out there as well, and it tends to take on a life of it's own.

Can I take this information and apply it in practice at home then?

Of course.

If you find that a line conditioner fails to quiet down a system, there is a very good possibility that it's ground loop intrusion causing the problem and not line voltage quality.

Edit: BTW, if you choose to modify any house wiring to reduce loops, keep in mind that you would be better served having a licensed electrician do the work. Code varies from place to place, and an experienced guy will know local code. Putting cable in the same conduit, box, or sometimes even very close (within the walls), while reducing loop area, may violate local code. Try not to violate local code, as code is there to protect you.

Some things, like running the cable in the next stud bay over from the AC runs as opposed to the other side of the house can make big differences both in noise and in near strike survivability.

Your only wire loop recourse that doesn't concern code, is the wiring on the living side of the sheetrock. Sometimes wire dress there makes a difference, but again, is dependent on what mechanism is intercepting the noise.

jn

 

[PENG]

Electricity does not work that way. The surge is a current source. That means current flowing through a first protector is, at the same time, also flowing through a second protector, and through any 'at risk' appliance. You have assumed protectors work by blocking or absorbing a surge. Protectors that would somehow absorb surges do not claim to protect from destructive surges.

From this first paragraph of your long post I think it is reasonable to assume you really don't know much about how electricity works. The thread seems like a long one so it would not surprise me if some one pointed this out already so others wouldn't be misled or confused.

 

[jneutron]

From this first paragraph of your long post I think it is reasonable to assume you really don't know much about how electricity works.

You are correct in your assumption.

jn

 

[westom]

From this first paragraph of your long post I think it is reasonable to assume you really don't know much about how electricity works.

Defined in that first paragraph is a current source. Linemen, computer techs, and others with little electrical knowledge would not know what is taught to 1st semester engineers. Often because 'current source' cannot be explained by a sound byte. And the concept requires math.

Current source applies to a type of electricity not provided by the AC utility and characteristic of a destructive type of surge. It explains why daisy chaining protectors do not increase protection:
Current Source

A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it. ...
Most sources of electrical energy (mains electricity, a battery, ...) are best modeled as voltage sources. Such sources provide constant voltage, ...
Conversely, a current source provides a constant current, as long as the load connected to the source terminals has sufficiently low impedance.

Low impedance for lightning is even wood, concrete, rocks, and, of course any protector that attempts to block a surge. Voltage is independent; increases as necessary to maintain that current flow. Arithmetic makes that obvious.

Does not matter how many protectors are daisy chained. That surge current incoming to a first protector is also and simultaneously outgoing into a second protector (because it is electricity). And simultaneously outgoing into the attached appliance. Does not matter how many volts each protector will block or absorb. Being a current source, lightning increases voltage as necessary to blow through each device in that chain.

Lightning even blows through a wooden church steeple. Even wood impedance is low enough to conduct that current. Steeple voltage increases as necessary so that a current source - ie lightning surge - will flow to earth. Materials normally assumed to be non-conductive (high resistance) become conductive (low impedance) to destructive current sources such as lightning. Unknown to many since this electrical concept is not taught to linemen and computer techs.

Either a destructive surge connects low impedance to what it seeks - earth ground. Or current will increase voltage as necessary to connect (blow through) to earth destructively via protectors and appliances. How high will that voltage rise?

Generally a 120 volt protector (rated at 330 volts) will fail because, in trying to block a current source, voltage rises to well above 900 volts. Voltage increased as necessary so that the current will flow. A surge only need apply enough voltage to the highest voltage protector. Then that voltage will blow through all lesser ones in that path.

jneutron summarized a completely different type of surge. He describes a voltage source. He did not know of current sources. A power strip manufacturer claims to protect from that type. Voltage source transients can be neutralized even by near zero joules in a power strip or even less joules in a UPS. Only a properly earthed solution averts damage from the other, destructive (current source) surge that may be hundreds of thousands of joules.

More disparaging remarks will follow from those who never learned how electricity works - who never heard of a current source. And who get angry because reality requires more than two paragraphs. What will follow are more replies inspired by a venomous ego with a technician's or linemen's education.

 

[Rickster71]

More disparaging remarks will follow from those who never learned how electricity works - who never heard of a current source. And who get angry because reality requires more than two paragraphs. What will follow are more replies inspired by a venomous ego with a technician's or linemen's education.

Oh...... now I understand.
You're simply a victim in all this.
56,303 members are all wrong about you.... because of their egos and lack of education.

And the concept requires math.

The only math anyone needs: Knowing that you are virtually at the the bottom of 56,303 members.

Shouldn't you be trolling the Psychology Today forum instead?

 

[westom]

56,303 members are all wrong about you.... because of their egos and lack of education.

Subverting reality is your specialty. A few egotists hate me 56,303 times more than others. 56,303 people did not vote. A few petty squatter voted. Angry because technical realities contradict popular myths. Boiling your venom is easy. Just cite basic electrical concepts. Your clan did not even know what a current source is.

Knowledge requires some math; cannot be learned in a black and white, subjective world where advertising replaces an education. Hoiw many more nasty votes did you enter to get me to 56,304?

Only the informed say where hundreds of thousands of joules harmlessly dissipate. Numbers (not personal attacks) define whether a protector is useful. Near zero joules in power strips even create a fire threat. A problem revealed with APC protectors that are grossly undersized; too few joules; a serious house fire threat.

Another and well proven solution averts damage from all types of surges including current sources. One must know what a current source is to understand why. So you again attack the messenger rather than post anything technically useful. It's so easy to get on your enemies list. Your ego is showing.

Arithmetic for a current source is too hard to understand. So it was simplified. Voltage increases as necessary so that a surge current will blow through. Destructive surges are a current source; not a voltage source as jneutron assumed. Only the informed say where hundreds of thousands of joules from a current source harmlessly dissipate.

 

[jneutron]

Arithmetic for a current source is too hard to understand.

Really? So then, Thevenin and Norton got it all wrong?? Perhaps you should google that, then add it to your cut and paste repertoire.

Destructive surges are a current source; not a voltage source as jneutron assumed.

You need a basic understanding of current, voltage, and the equivalent circuits. Only you can decide to learn, we can't force feed you.

We can laugh at you however. You provide hours of entertainment with your childish understandings and demeanor.

I repeat to all, I am not paying w-dude to post stupid things... he makes me look good all by himself..


PS. Darkwing, If you wish to, would you post my PM to you in this thread? The information is actually useful to all. Thanks.
jn

 

[jneutron]

The only math anyone needs: Knowing that you are virtually at the the bottom of 56,303 members.

Shouldn't you be trolling the Psychology Today forum instead?

Then how can he become the best on this site?? He's not yet #1.

jn

 

[PENG]

Voltage increases as necessary so that a surge current will blow through.

This time your post is shorter so I will respond properly. You could be right if you referred to an artificially created surge, i.e. if there is such a thing as a surge similator/creater. Then you can crank up the voltage (the created one) source that you have controls, to overcome an impedance, to reach a say, targe surge current value. The same does not apply to surge typically resulted from switching (obviously there are all sorts of switching, intended or unintended) and lightning etc. I believe the OP was not referring to intentionally created/generated surges for experimental or other reasons. I believe he referred to surges resulting from switching of complex circuits and lightning. As such, those voltages cannot "increases as necessary". I am not sure if you are confused with the fact that for a given current, the higher the impedance it flows through the higher will be the voltage developed across the impedance load/path, but that does not mean if you increase the impedance the "SOURCE" voltage will increase to force the target current through.

A more natural and practical example of a created source would be the current transformer. The output voltage of a current transformer would indeed increase to force the target current through the load regardless of its impedance, but only to a point. Let's say the primary current is 100A and the current transformer ratio is 100:5, then the secondary voltage of a C.T. will try to drive 5A through the load connected to its secondary winding. So if you increase the load impedance, it will develop a higher voltage to maintain the current, to the point it could get dangerously high and damage itself if you increase the load impedance too much, such as an open circuit. That is not the same as a voltage source from lightning or surges from switching complex circuit. I have no need to ask Dr. Google, but you could if you wish to search for more. I am not a fan of long post, but I guess I owe you this one.

not a voltage source as jneutron assumed. Only the informed say where hundreds of thousands of joules from a current source harmlessly dissipate.

I did not read about what jneutron "assumed", but I had read a few posts by him in the past. It is reasonable to assume he is knowledgeable in electrical theory. For someone who understands electrical theory well, one has to be knowledgeable in advanced maths and physics, not just simple arithmetic.

 

[markw]

Then how can he become the best on this site?? He's not yet #1.

jn

No, but he is, without a doubt # 2.

 

[westom]

I believe he referred to surges resulting from switching of complex circuits and lightning. As such, those voltages cannot "increases as necessary". I am not sure if you are confused with the fact that for a given current, the higher the impedance it flows through the higher will be the voltage developed across the impedance load/path, but that does not mean if you increase the impedance the "SOURCE" voltage will increase to force the target current through.

Lightning is a typical example of a surge. Install protection to make direct lightning strikes irrelevant. Then lesser surges (ie due to utility switching) are also made irrelevant. Lightning voltages can increase so much as easily blow through anything including power strip protectors (typically so undersized as to fail catastrophically at maybe 900 volts and only hundreds of joules). Lightning voltages are potentially so high as to even make wooden church steeples into electrical conductors. Again, voltage increases as necessary to conduct to earth via wood.

Not only is that lesser surge also a current source (albeit with a lesser possible maximum voltage). But is also a longitudinal mode current. jneutron has confused trivial normal mode currents with typically destructive longitudinal mode currents. Protection from normal mode transients is routinely inside all appliances.

A longitudinal mode transient (ie lightning) is either non-destructive due to protection routinely inside all appliances. Or voltage increases so high as to blow through that appliance. T0 make a destructive connection to earth. Appliances are damaged when a current source (ie lighting) increases voltage well above the maybe 1000+ volts that appliances are designed to withstand without damage. Sometimes a power strip protector even bypasses an appliance's internal protection.

Voltage does not increase if that current (ie lightning) is connected low impedance (ie a connection less than 10 feet) to single point earth ground. This solution is proven by over 100 years of science and experience. Then surges due to stray cars, utility switching, linemen errors, etc are also made irrelevant. Some delivering more energy than lightning; others less. All create no damage, even to a protector, IF properly installed.
</SPAN>
Spend less money to have protection even from direct lightning strikes. Then all types of surges are routinely averted.

 

[PENG]

Lightning is a typical example of a surge. Install protection to make direct lightning strikes irrelevant. Then lesser surges (ie due to utility switching) are also made irrelevant. Lightning voltages can increase so much as easily blow through anything including power strip protectors (typically so undersized as to fail catastrophically at maybe 900 volts and only hundreds of joules). Lightning voltages are potentially so high as to even make wooden church steeples into electrical conductors. Again, voltage increases as necessary to conduct to earth via wood.

Not only is that lesser surge also a current source (albeit with a lesser possible maximum voltage). But is also a longitudinal mode current. jneutron has confused trivial normal mode currents with typically destructive longitudinal mode currents. Protection from normal mode transients is routinely inside all appliances.

A longitudinal mode transient (ie lightning) is either non-destructive due to protection routinely inside all appliances. Or voltage increases so high as to blow through that appliance. T0 make a destructive connection to earth. Appliances are damaged when a current source (ie lighting) increases voltage well above the maybe 1000+ volts that appliances are designed to withstand without damage. Sometimes a power strip protector even bypasses an appliance's internal protection.

Voltage does not increase if that current (ie lightning) is connected low impedance (ie a connection less than 10 feet) to single point earth ground. This solution is proven by over 100 years of science and experience. Then surges due to stray cars, utility switching, linemen errors, etc are also made irrelevant. Some delivering more energy than lightning; others less. All create no damage, even to a protector, IF properly installed.

Spend less money to have protection even from direct lightning strikes. Then all types of surges are routinely averted.

I am afraid you've got it upside down. Voltage produces current, governed by Ohm's law that everyone seems to know. Even currents produced by lightning started with voltage between point A and point B. Of course the origin of a direct lightning hit has high enough voltage to drive very high current through things that stand between it's point A to it's target point B. So you may say in that case it is like a current source and I don't think anyone would argue hard against that point.

The surges in our home that are resulted from lightning are typically and hopefully very indirectly related to lightning hits, and it will not likely behaves the same as a direct lightning hit that offers extremely high voltage and what I would call equivalent high internal (or source) impedance. I doubt the OP was referring to surge protection from direct lightning hit when he started this thread. If your electronic gear is in the path of a direct lightning hit, no surge protection systems you can buy online or from Home Depot will protect you from it.

Surges resulted from switching in appliances including HVAC systems in our homes, or within the nearby ultility power distribution systems are far from being anything like a real current source, ie. high voltage and high internal impedance.

 

[westom]

I am afraid you've got it upside down. Voltage produces current, governed by Ohm's law that everyone seems to know.

So why are 1st semester engineres taught about current sources and voltage sources? Did you ignore the Wikipedia citaon that demonstrates your mistake?

Surge protection of appliances, like surge protection of buildings, means near zero voltages and extremely high amperes (ie 20,000 amps) Any device that could foolishly try to stop or block a surge (a current source) creates and suffers from a high voltage. That voltage only exists when a current source is blocked (see the formula V=IR). Direct lightning strikes without damage has always been about connecting a surge current harmlesslyl to earth so that a near zero voltage exists.

Another popular urban myth is surges created by power cycling major appliances. If those appliances create a surge, then they destoy themselves. If they create surges, the the protector is on the surge generating appliance - not on the victims. But those appoliances only create noise; not surges. Noise that may be as much as ten volts. Noise easily made irrelevant by protection already inside every appliance. Protection required by international design standards even decades before an IBM PC existed.

But if a major appliance does create a surge, what is best located and has sufficient joules to eliminate such surges? The 'whole house' solution.

And finally, if HVAC is creating surges daily, then MOVs in power strips are degraded (fail) in weeks or months. They are not designed for events that occur hourly. Their design specs are for events that occur maybe once every seven years. Just another reason why you know 120 volt appliances (ie HVAC) are not creating 330+ volt surges hourly or daily. Read the number on that protector box. It ignored any transiet (ie 10 volt noise) that does not exceed 330 volts. How often do your appliances suffer 330+ volt surges from the vacuum or HVAC? Never. But the myth is popular and easy to promote in a sound byte to consumers who ignore numbers.

Read numbers in that Wikipedia citation rather than assume all electricity comes from a voltage source. Even electricians are not taught about current sources. A current source means that constant current must flow. Therefore from V=IR, voltage must increase if that current is blocked. That increased voltage is why protectors that must block a surge are easily destroyed - provide ineffective protection.

 

[jneutron]

I post this for all others. W-dude has no understanding, so can learn nothing.

Lightning is a typical example of a surge.

Lightning is but one example, and it is comprised of 4 categories.
1. Direct hit to house.
2. Direct hit to powerlines.
3. Earth strike close to transmission lines.
4. Earth strike close to house.

Branch multiport SPD's are the best protection for #4.
Branch and whole house are best for 3.
The utility with it's MOV's and spark gaps are best for #2.
#1 requires a faraday cage construction diverting all current as a cylindrical sheet around the entire house structure. Skyscrapers and large buildings do that via building structural columns.

The best one can hope for in a residential setting is diversion of the bulk of the energy via a grounding conductor, preventing large ground loops with low level circuits, and a point of use multiport SPD. Surge devices at the service entrance cannot prevent ground loop voltages.

Lightning protection at the house is designed to minimize fire potential.

power strip protectors (typically so undersized as to fail catastrophically at maybe 900 volts and only hundreds of joules).

Maybe hundreds of joules? As opposed to actual testing of MOV's with actual numbers? Make up some more numbers..

Lightning voltages are potentially so high as to even make wooden church steeples into electrical conductors.

You have no idea how lightning propagates. I'd explain leading edge voltage gradient ionization to you , but that again, is a waste of time..

jneutron has confused....

jneutron just finished wiring a billion dollar machine that works... jneutron's only confusion is an expectation of intelligence from you...

Appliances are damaged when a current source (ie lighting) increases voltage well above the maybe 1000+ volts that appliances are designed to withstand..

The standard reverse breakdown voltage for off line semiconductors is 800 volts. Guess again with your made up numbers.

Sometimes a power strip protector even bypasses an appliance's internal protection.

Really? How.

Now, don't make something up...

I am afraid you've got it upside down.

Peng, you will eventually realize he has no understanding. If you were to search, you would find that everything he posts is a repeat from the last decade or so from multiple sites. So much so, that everybody at some point in time thinks he's simply a bot with rudimentary programming.

jn

 

[jneutron]

For everybody's illumination, I've hilited in red the abysmal errors consistent with someone with no engineering or math education.

So why are 1st semester engineres taught about current sources and voltage sources? Did you ignore the Wikipedia citaon that demonstrates your mistake?

Surge protection of appliances, like surge protection of buildings, means near zero voltages and extremely high amperes (ie 20,000 amps) Any device that could foolishly try to stop or block a surge (a current source) creates and suffers from a high voltage. That voltage only exists when a current source is blocked (see the formula V=IR). Direct lightning strikes without damage has always been about connecting a surge current harmlesslyl to earth so that a near zero voltage exists.

Another popular urban myth is surges created by power cycling major appliances. If those appliances create a surge, then they destoy themselves. If they create surges, the the protector is on the surge generating appliance - not on the victims. But those appoliances only create noise; not surges. Noise that may be as much as ten volts. Noise easily made irrelevant by protection already inside every appliance. Protection required by international design standards even decades before an IBM PC existed.

But if a major appliance does create a surge, what is best located and has sufficient joules to eliminate such surges? The 'whole house' solution.
And finally, if HVAC is creating surges daily, then MOVs in power strips are degraded (fail) in weeks or months. They are not designed for events that occur hourly. Their design specs are for events that occur maybe once every seven years. Just another reason why you know 120 volt appliances (ie HVAC) are not creating 330+ volt surges hourly or daily. Read the number on that protector box. It ignored any transiet (ie 10 volt noise) that does not exceed 330 volts. How often do your appliances suffer 330+ volt surges from the vacuum or HVAC? Never. But the myth is popular and easy to promote in a sound byte to consumers who ignore numbers.

Read numbers in that Wikipedia citation rather than assume all electricity comes from a voltage source. Even electricians are not taught about current sources. A current source means that constant current must flow. Therefore from V=IR, voltage must increase if that current is blocked. That increased voltage is why protectors that must block a surge are easily destroyed - provide ineffective protection.

 

[westom]

SPDs do not do surge protection. Will its hundreds of joules magically absorb surges that are hundreds of thousands of joules? Why must this well proven reality be reposted repeatedly. Because many only believe the first thing told by advertising. Then reality with numbers is just too hard to accept. Protection is always about where hundreds of thousands of joules harmlessly dissipate. On a path that remains outside a building so that it remains outside of all appliances. Protection is always about a courrent source that creates near zero voltage. Therefore facilities that cannot have damage connect a completely different device (a 'whole house' protector) low impedance to single point earth ground. This well proven science has not changed because Belkin or Monster has sucessfully promoted myths.

If nearby surges are so destructive, then a nearby lightning strike means all car radios, wrist watches, mobile phones, and calculators are destroyed. So lets do the numbers that jneutron does not post because he cannot. Technicians typically do not learn this stuff.

A nearby strike induces thousands of volts on a long wire antenna. An NE-2 neon glow lamp (milliamp device) is connected to that antenna. Less than milliamps through that NE-2 means thousands of volts drops to tens of volts. Nearby strikes are so trivial as to be made irrelevant by protection already inside every appliance.

In another example, a lightning rod was struck. That maybe 20,000 amps flowed to earth on a wire just four feet away from an IBM PC. Was the PC harmed? Of course not. It (and all other electronics in the building) did not even blink. Because nearby surges are routinely irrelevant. Damage is from the direct strike. A direct strike that connects to earth without entering the building (or appliance) causes no damage.

One would know how trivial the nearby strike really is if one had learned electromagnetic field theory. But that requires numbers. Field theory is not taught to technicians. How does an NE-2 so easily eliminate those thousands of volts. Obvious from the numbers and from industry experience.

Anything that would stop or block a surge (ie an SPD) is bogus protection. Facilities that cannot have damage properly earth a 'whole house' protector that is sized to not be harmed even by direct lightning strikes. For a homeowner, that is about $1 per protected appliance. Best protection is also least expensive.

jneutron again makes accusations he cannot suport with facts and numbers. What happens to hundreds of thousands of joules? He never says. Answering that question would demonstrate why he resorts to personal attack and empty accuastions. And no numbers. By being only nasty and insulting, that makes him educated? He did not even know what current sources or wire impedance was until he was challenged. Wikipedia was his friend. He still does not know what a longitudinal current is. And has no idea what that is relevant. It is not routinely taught to techicians. So he will again do what he does best; post insults and cheapshots.

 

[jneutron]

SPDs do not do surge protection.

As opposed to what the NEC says, what UL says, what every NRTL says. Only you are right.

Because many only believe the first thing told by advertising.

The NFPA does not advertise. Nor do any Nationally Recognized Testing Labs on the planet.

If nearby surges are so destructive, then a nearby lightning strike means all car radios, wrist watches, mobile phones, and calculators are destroyed. So lets do the numbers that jneutron does not post because he cannot. Technicians typically do not learn this stuff.

All my electrical technicians understand this. Some of the mechanical ones do as well. You do not understand Faraday's law of induction.

Numbers? You think making up numbers is "doing numbers?"

Stop being an internet clown.

jn

 

[jneutron]

jneutron again makes accusations he cannot suport with facts and numbers.

I have stated that you have no understanding of electricity, that you are an internet poser with no education on the topic. My facts are your posts.

Over the years, I've detailed faraday's law of induction, amperes law, mutual and self inductance, time varying magfield based loop area induction. Numbers. Numbers which you ignore.

So he will again do what he does best; post insults and cheapshots.

You've no idea what I do best.

Calling you out as a poser and internet clown is a perk. I thank you for the multiple opportunities you provide, by posting your cut and paste gibberish.

Next install please? I need a good laugh..

jn

 

[westom]

If jneutron had industry experience, then he knew neither UL nor NEC say anything about how surge protection works. Those non-profit organizations only discuss human safety. Anyone with basic electrical experience would know that.

UL created UL1449 because so many power strips were causing house fires. They had to keep tightening the standards - now third edition - because so many UL 1449 protectors were still creating house fires.

Schneider Electric bought APC. Then discovered some APC protectors were so dangerous as to be removed immediately. All power strip protectors have this problem. But these APC protectors with a UL 1449 listing still caused fires - are especially dangerous:
Schneider Electric Recalls APC Surge Protectors Due to Fire Hazard | CPSC.gov

NEC describes how to wire a building so as to not threaten human life. NEC is part of the National Fire Protection Association. That addresses safety issues. UL describes how to construct appliances so as to not threaten human life. UL required appliances to be lab tested before that appliance can be UL listed. Because UL does not rate what any appliance (ie power strip) does. UL is only about human safety issues - ie fire.

jnetron would know that if he really was technically informed. Lack of basic knowledge is why he resorts to cheapshots and insults. And no numbers.