Do Power Strips & Laptops Mix?

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Do Power Strips & Laptops Mix?

Postposted on Thu May 31, 2012 11:29 am

Do laptops benefit from being plugged into power strips? This is the question I've been asking myself lately... I've almost always use power strips for desktops to protect from power surges. Lately I've been hearing stories that laptops don't need to be connected to power strips. That laptops have built in surge protectors.

If anyone here could shine some more light on this situation I'd appreciate it.
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Re: Do Power Strips & Laptops Mix?

Postposted on Thu May 31, 2012 11:37 am

I am not sure if there is a "built in surge protector," but functionally speaking, an AC to DC converter would be able to absorb a surge of electricity with the components inside. Now a good burst of electricity might kill your transformer, but it should protect your laptop from getting fried.
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Re: Do Power Strips & Laptops Mix?

Postposted on Thu May 31, 2012 12:01 pm

Why would the AC-to-DC power transformer in a laptop power plug be any less susceptible to surges than the AC-to-DC power transformer in a desktop?
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Re: Do Power Strips & Laptops Mix?

Postposted on Thu May 31, 2012 12:02 pm

The question is this: if a surge causes the first link in the chain to die sacrificially protecting your system, which would you rather it be? A commodity surge protector, or the proprietary power supply for your laptop?
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Re: Do Power Strips & Laptops Mix?

Postposted on Thu May 31, 2012 12:21 pm

nerdrage wrote:Why would the AC-to-DC power transformer in a laptop power plug be any less susceptible to surges than the AC-to-DC power transformer in a desktop?

Two ways, actually.

1. The battery can also soak up some of the surge.

2. Less power. Electric components have points at which they fail (any combination of voltage, current, or power). When this happens, connections are usually broken rather than shorted (meaning they stop the flow of electricity rather than allowing even more through). A lower failure level would mean that the stuff in the transformer is more likely to fail before levels rise high enough to damage components down the line. So basically think of that black box as a really expensive fuse.

A desktop PSU could also do the same thing, which shouldn't be surprising if you've replaced one after a storm and had the computer boot up just fine. I had to replace at least a dozen PSUs at my university after some summer storms, and every single computer survived.

EDIT: Ubergerbil probably had the best response. Electricity will flow until something breaks. The idea of a surge protector is to break before anything connected to it does.
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Re: Do Power Strips & Laptops Mix?

Postposted on Thu May 31, 2012 12:29 pm

superjawes wrote:I am not sure if there is a "built in surge protector," but functionally speaking, an AC to DC converter would be able to absorb a surge of electricity with the components inside. Now a good burst of electricity might kill your transformer, but it should protect your laptop from getting fried.


Sure, the transformer might absorb a surge; and given a larger surge, the damage might well be limited to the transformer itself.

But a power strip is designed to absorb a surge, will absorb a much larger surge; and is far easier and cheaper to replace if damaged.
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Re: Do Power Strips & Laptops Mix?

Postposted on Thu May 31, 2012 2:28 pm

The main difference is that in a desktop, any surge serious enough to really wreck the PSU will then apply the consequences directly to the system components via the PSU output. A laptop is naturally constructed as an uninterruptible power supply and the internal converter has secondary voltage regulation and protection mechanisms after the AC-DC converter in the brick, meaning that the first-order damage would more likely be confined to the brick.

I wouldn't bother carrying a surge strip in my laptop bag, but if you frequently plug in your laptop at one particular location (e.g. your desk), there's certainly no harm in using a high-quality surge strip.
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Re: Do Power Strips & Laptops Mix?

Postposted on Fri Jun 01, 2012 4:49 pm

Thanks for all the great info everybody. Learned a lot. :)
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Re: Do Power Strips & Laptops Mix?

Postposted on Sat Jun 02, 2012 3:40 am

The power brick for your laptop is no more or less likely to survive a power surge than the PSU in a desktop system. TBH beyond that it is probably a wash... as ludi notes, the laptop will have additional power regulation internally, but I'm not convinced that buys you much in the event of a power surge. The main difference is that (assuming a good battery is installed) a laptop effectively has a built-in UPS, so you'll be less susceptible to data corruption/loss in the event of a power failure than you would be on a desktop without a UPS.
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Re: Do Power Strips & Laptops Mix?

Postposted on Sat Jun 02, 2012 8:06 am

Everybody worries about surges but a good PSU regardless of if it is a laptop or desktop should have surge suppression built in to handle the moderate stuff (nothing is going to handle direct lightening strikes). What's far more damaging are the brown outs because electronics typically tries to draw constant power - it's not like a resistive load. This means that when the voltage sags the current increases and can burn out traces and components that are just too small for the current flow. The laptops inbuilt UPS, its battery, will prevent this damage from occuring.
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Re: Do Power Strips & Laptops Mix?

Postposted on Sat Jun 02, 2012 9:41 am

malebolgia wrote:I've almost always use power strips for desktops to protect from power surges.


I'm no electricity whiz, but there is a significant difference between a simple power strip and an actual surge protector, right?
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Re: Do Power Strips & Laptops Mix?

Postposted on Sat Jun 02, 2012 11:44 pm

absurdity wrote: I'm no electricity whiz, but there is a significant difference between a simple power strip and an actual surge protector, right?

Read manufacturer spec numbers to see the difference. A power strip protector claims near zero protection and can give a surge even more potentially destructive paths through adjacent appliances. A power strip is zero protection and does not give the surge more destructively paths.
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Re: Do Power Strips & Laptops Mix?

Postposted on Sun Jun 03, 2012 12:20 am

westom wrote:
absurdity wrote: I'm no electricity whiz, but there is a significant difference between a simple power strip and an actual surge protector, right?

Read manufacturer spec numbers to see the difference. A power strip protector claims near zero protection and can give a surge even more potentially destructive paths through adjacent appliances. A power strip is zero protection and does not give the surge more destructively paths.

Manufacturer's specs aren't particularly helpful for people who don't know what joules are, or how many are typically carried in a lightning-induced power surge.

I also question your implication that a "surge strip" is actually worse than a vanilla power strip (though I do agree that they're probably not much better if you get a surge that your PSU couldn't have handled on its own).
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Re: Do Power Strips & Laptops Mix?

Postposted on Sun Jun 03, 2012 7:21 am

just brew it! wrote: Manufacturer's specs aren't particularly helpful for people who don't know what joules are, or how many are typically carried in a lightning-induced power surge.
Joules are taught even in high school science. Surges that are destructive can be as much as hundreds of thousands of joules. Protection is always about where energy dissipates. As in always.

A device called a protector and located adjacent to an appliance must either block or absorb that energy. How do its hundreds of joules make hundreds of thousands of joules disappear? Such protectors even have a history of creating house fires.

Another completely different device and located where wires enter the building can connect that energy to what it seeks. Earth ground. Then hundreds of thousands of joules are absorbed harmlessly outside the building. Then that energy is not inside hunting for earth ground destructively via appliances. Facilities that can never have damage always earth a 'whole house' protector. Do not waste money on power strip protectors.

A protector is only as effective as its low impedance (ie 'less than 10 foot') connection to earth. The difference between protectors that even earth direct lightning strikes. And remain functional. Verses grossly undersized protectors that do not even claim protection from a typically destructive surge. However, a majority buy and recommend the inferior product. Advertising myths are easily believed by a majority who ignore numbers. Who think subjectively. And therefore all but want to be scammed. Honesty means a perspective only possible with numbers.
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Re: Do Power Strips & Laptops Mix?

Postposted on Sun Jun 03, 2012 11:13 am

westom wrote:
just brew it! wrote: Manufacturer's specs aren't particularly helpful for people who don't know what joules are, or how many are typically carried in a lightning-induced power surge.

Joules are taught even in high school science.

Yes, and what percentage of the general public (or even of people who read forums like this one) actually remember everything they were taught in high school physics?
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Re: Do Power Strips & Laptops Mix?

Postposted on Sun Jun 03, 2012 11:49 am

The best information on surges and surge protection I have seen is at:
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.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 a major organization of electrical and electronic engineers).
And also:
http://www.nist.gov/public_affairs/prac ... gesfnl.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 surge guide is aimed at people with some technical background.

westom wrote:A device called a protector and located adjacent to an appliance must either block or absorb that energy

Nonsense.

With minimal reading skills westom could find out in the IEEE surge guide how plug-in protectors really work. It isn't by "blocking" or "absorbing".

westom wrote:How do its hundreds of joules make hundreds of thousands of joules disappear?

The author of the NIST surge guide investigated how much energy might be absorbed in a MOV (the protection element in almost all surge protectors) in a plug-in protector. Branch circuits were 10M and longer, and the surge on incoming power wires was up to 10,000A . (That is the maximum that has any reasonable probability of occurring and is based on a 100,000A strike to a utility pole adjacent to the house in typical urban overhead distribution.) The maximum energy at the MOV was a surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less. A plug-in protector, wired correctly (as below), is very likely to protect from a very near very strong lightning strike. Plug-in protectors with much higher ratings are readily available. High ratings mean long life.

(One reason the energy is so small is that at about 6,000V there is arc-over from service panel busbars to the enclosure. Since the enclosure is connected to the earthing system that dumps most of the energy of a large surge to earth.)

(Neither service panel or plug-in protectors work by absorbing the surge. But they both absorb some energy in the process of protecting.)

westom wrote:Such protectors even have a history of creating house fires.

UL has, since 1998, required thermal disconnects for overheating MOVs. Any surge protector in the US should be listed under UL1449. (Some UPSs don't seem to be.)

westom wrote:Facilities that can never have damage always earth a 'whole house' protector.

Service panel protectors are a real good idea.
But from the NIST guide:
"Q - Will a surge protector installed at the service entrance be sufficient for the whole house?
A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

A service panel protector with adequate ratings (see the IEEE surge guide) is likely to protect anything connected only to power wires. But service panel suppressors do not by themselves prevent high voltages from developing between power and phone/cable/... wires. The NIST surge guide suggests that most equipment damage is from high voltage between power and signal wires.

westom wrote:A protector is only as effective as its low impedance (ie 'less than 10 foot') connection to earth.

The IEEE surge guide explains (starting page 30) that plug-in protectors do not work primarily by earthing a surge. They work by limiting the voltage from each wire (power and signal) to the ground at the protector. The voltage between wires going to the protected equipment is safe for the protected equipment.

When using a plug-in protector all interconnected equipment needs to be connected to the same protector. External connections, like cable, also must go through the protector. Connecting all wiring through the protector prevents damaging voltages between power and signal wires.

westom wrote:Verses grossly undersized protectors

Westom thinks all plug-in protectors are "grossly undersized".

The plug-in protector I am using that has the lowest ratings has a total joule rating of 1770 - 90,000 surge amps. Compare that with the 35 joules maximum above. (The 90,000A is far above what can appear on the power service wires. The high surge amp rating just goes along with the high joule rating.)

westom wrote:that do not even claim protection from a typically destructive surge.

Nonsense.

Some manufacturers even have warranties for protected equipment.

Both the IEEE and NIST surge guides say plug-in protectors are effective.

westom wrote:Honesty means a perspective only possible with numbers.

If westom was honest he wouldn't compulsively post blatantly false information all over the internet.

===========================
Wall warts generally seem to provide surge protection. I don't know why - information comes from the author of the NIST surge guide. I wouldn't think that would apply to a power brick.

A very limited investigation including the author of the NIST surge guide and an insurance company found desktop computers with surge damage often had blown power supply fuses and shorted diodes on the line side DC power supply. Often they would work after replacing those parts. That is consistent with comments by superjawes.

If a computer has phone or other signal wires attached the damage may be other than the power supply.

One precaution would be to disconnect external power to a laptop during thunderstorms and run on battery.
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Re: Do Power Strips & Laptops Mix?

Postposted on Sun Jun 03, 2012 2:58 pm

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Re: Do Power Strips & Laptops Mix?

Postposted on Sun Jun 03, 2012 3:16 pm

Ah, so this is just like the '80s college tours of the scripted Timothy Leary/G. Gordon Liddy "debates", no?
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Re: Do Power Strips & Laptops Mix?

Postposted on Sun Jun 03, 2012 10:34 pm


Oh, he's been to TR three of four times already. Once you figure out who he is and what his agenda amounts to, it's best just to get popcorn :D
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Re: Do Power Strips & Laptops Mix?

Postposted on Mon Jun 04, 2012 9:04 am

Captain Ned wrote:Ah, so this is just like the '80s college tours of the scripted Timothy Leary/G. Gordon Liddy "debates", no?

Westom goggles for "surge" to post his wisdom. Some of what he says is good, some not so good and some is complete nonsense. One of his very often posted opinions is that plug-in protectors (including UPSs) do not work - complete nonsense. He has posted this on an astonishing number of forums. Googling for ["westom" surge] returns about 1400 hits. (A year ago there were about 14,000 hits.) There are more under other names. People who have been on the internet for a long time say he has been doing this for maybe 10 years, going back to Usenet.

I got tired of his drivel after seeing it 5 times in a short period on 2 newsgroups I follow. But his technobabble posts can be convincing. I counter only a few of his rants. I can back up almost all of what I post from technical sources. And it is likely that you did not know all of what I posted. But the arguments can be annoying.

If you are interested in surge protection the 2 sources I posted have excellent information from reliable sources and cover a lot more than has come up here.
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Re: Do Power Strips & Laptops Mix?

Postposted on Mon Jun 04, 2012 10:21 am

bud-- wrote: Westom goggles for "surge" to post his wisdom.

Bud is paid to post here. His job is to promote protectors that do not claim protection. He has followed me everywhere to post attacks. Why did he join yesterday? It is his job. He joins discussions to attack me. It is his job.

Ask bud for numeric specs for any plug-in protector. He refuses. Honesty means facts supported by numbers. bud cannot post manufacturer numbers. Those protection spec numbers do not exist. His very first post is to attack the messenger. To make subjective claims. To protect sales.

Honesty says where hundreds of thousands of joules dissipate. Then learn what page 17 of his NIST citation says:
A very important point to keep in mind is that your surge protector will work by diverting the surges to ground. The best surge protection in the world can be useless if grounding is not done properly.


Bud recommends protectors that clamp ... to nothing. Reality: it sometimes clamps a surge to earth destructively via any nearby appliance. IEEE citation, page 42 figure 8, shows a protector too close to appliances and too far from earth ground. It earths a surge *8000 volts* destructively through a nearby TV. It may earth destructively via the attached TV1 or destructively via any other nearby appliance (TV2). Since it does not make a low impedance (ie ‘less than10 foot’) connection to earth, then it must earth energy via nearby appliances. As bud’s specification numbers show. Oh. He never posts engineering facts. He cannot post what does not exist.

Effective protectors clamp low impedance (ie ‘less than 10 feet’) to earth ground. What a protector clamps to defines protection or no protection. No earth ground means no effective protection.

Why do facilities that can never have damage always earth a ‘whole house’ protector. Informed facilities use a less expensive solution defined by the IEEE as “99.5% to 99.9%” of the protection.

Informed consumers install protectors from more responsible companies including GE, Intermatic, Siemens, Cutler-Hammer (Eaton), ABB, and Leviton. Protectors that actually connect surges harmlessly to earth.

bud's citation defines effective and ineffective solutions. The NIST on page 17 says:
The best surge protection in the world can be useless if grounding is not done properly.
The most critical component of any protection system even 100 years ago: single point earth ground.

Protection is always about where energy dissipate. A TV 8000 volts destroyed because an adjacent protector cannot be earthed. Any protector without earthing is called “useless”. Every facility that cannot have damage uses earthed protectors. Where do hundreds of thousands of joules dissipate if all but invited inside the house? Destructively via appliances.
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Re: Do Power Strips & Laptops Mix?

Postposted on Mon Jun 04, 2012 10:55 am

westom wrote:
bud-- wrote: Westom goggles for "surge" to post his wisdom.

Bud is paid to post here. His job is to promote protectors that do not claim protection. He has followed me everywhere to post attacks. Why did he join yesterday? It is his job. He joins discussions to attack me. It is his job.

Ask bud for numeric specs for any plug-in protector. He refuses. Honesty means facts supported by numbers. bud cannot post manufacturer numbers. Those protection spec numbers do not exist. His very first post is to attack the messenger. To make subjective claims. To protect sales.

Honesty says where hundreds of thousands of joules dissipate. Then learn what page 17 of his NIST citation says:
A very important point to keep in mind is that your surge protector will work by diverting the surges to ground. The best surge protection in the world can be useless if grounding is not done properly.


So you're saying that you are personally so large a threat to the power strip industry that they actually hire guys like Bud to follow you around on the internet and dispute things that you write on forums?
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Re: Do Power Strips & Laptops Mix?

Postposted on Tue Jun 05, 2012 9:30 am

westom wrote:Bud is paid to post here. His job is to promote protectors that do not claim protection.

Lie #1.

If westom had valid technical arguments he wouldn't have to lie about others. My only association with surge protection is I am using some surge protectors.

westom wrote:Ask bud for numeric specs for any plug-in protector. He refuses. Honesty means facts supported by numbers. bud cannot post manufacturer numbers. Those protection spec numbers do not exist.

Lie #2.

A 10 year old can find specs. So can anyone here except westom.
I have posted specs many times. So have others. Westom always ignores them and repeats one of his favorite lies.

westom wrote:Honesty says where hundreds of thousands of joules dissipate.

If westom could think he would have found out.

Repeating:
At about 6kV there is arc-over from service panel busbars to the enclosure. After the arc is established the voltage is hundreds of volts. Since the enclosure is connected to the earthing system that dumps most of the surge energy to earth.

westom wrote:Then learn what page 17 of his NIST citation says:

Everyone is in favor of earthing building electrical systems.
But what does the NIST surge guide really say about plug-in protectors?
They are "the easiest solution".
And "one effective solution is to have the consumer install" a multiport plug-in suppressor.

With no sources that agree with him westom has to misrepresent what the NIST says.

westom wrote:Bud recommends protectors that clamp ... to nothing.

I recommend only accurate information. Informed people can decide what protection is appropriate.

Both the IEEE and NIST surge guides say plug-in protectors are effective.

The IEEE surge guide explains how plug-in protectors work for anyone who can think.

westom wrote:Reality: it sometimes clamps a surge to earth destructively via any nearby appliance. IEEE citation, page 42 figure 8, shows a protector too close to appliances and too far from earth ground. It earths a surge *8000 volts* destructively through a nearby TV.

Anyone with minimal mental abilities can discover what the IEEE guide says in this example:
- A plug-in protector protects the TV connected to it.
- "To protect TV2, a second multiport protector located at TV2 is required."
- The illustration "shows a very common improper use of multiport protectors"
- In the example a surge comes in on a cable service with the ground wire from cable entry ground block to the earthing system at the power service that is far too long. In that case the IEEE guide says "the only effective way of protecting the equipment is to use a multiport [plug-in] protector."
- westom's favored power service protector would provide absolutely NO protection.

It is simply a lie (#3) that the plug-in protector in the IEEE example damages the second TV.

With no sources that agree with him westom has to misrepresent what the IEEE says.

westom wrote:He never posts engineering facts.

Lie #4

I post links to the IEEE and NIST surge guides. They contain "engineering facts".
Westom has no source that agrees with him that plug-in protectors are effective.

westom wrote:No earth ground means no effective protection.

Westom's mantra protects him from conflicting thoughts (aka reality).

Westom has an apparently religious belief (immune from challenge) that surge protection must directly use earthing. Since plug-in protectors are not well earthed westom believes they can not possibly protect.

The IEEE surge guide explains that plug-in protectors do not work primarily by earthing a surge. They work by limiting the voltage from each wire to the ground at the protector.

Westom is evangelical in his belief in earthing. That appears to be why he posts his belief that plug-in protectors do not work all over the internet.

westom wrote:Why do facilities that can never have damage always earth a ‘whole house’ protector. Informed facilities use a less expensive solution defined by the IEEE as “99.5% to 99.9%” of the protection.

Lie #5.

The 99+% figures are from the IEEE "Green" book and are for lightning rods. They are not for service panel protectors.

With no sources that agree with him westom has to misrepresent what the IEEE says.

westom wrote:Informed consumers install protectors from more responsible companies including GE, Intermatic, Siemens, Cutler-Hammer (Eaton), ABB, and Leviton.

All of westom's "responsible companies" make plug-in protectors and say they are effective.

For real science read the IEEE and NIST surge guides. Excellent information on surge protection. And both guides say plug-in protectors are effective.

Pass the popcorn.
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Re: Do Power Strips & Laptops Mix?

Postposted on Tue Jun 05, 2012 3:16 pm

cphite wrote: So you're saying that you are personally so large a threat to the power strip industry that they actually hire guys like Bud to follow you around on the internet and dispute things that you write on forums?

Many spend $45 or $100 for a protector circuit that also sells in Wal-Mart for $7. Obscene profit margins are created by myths and spin. Read more lies and half truths from his 'cut and paste' replies. He even ignores that his own citation says. A plug-in protector (no earth ground) is "useless".

Meanwhile, if that protector does protection, then he quoted a number for each type of surge. If a ten year old can find them, then he must be nine years old. Reality: he cannot post what does not exist. He will post endlessly because he is paid to protect profits.

A protector is only as effective as its earth ground. As was understood even 100 years ago. Only solution always found in any facility that cannot have damage: proper earthing and a 'whole house' protector. Cost: about $1 per protected appliance.

Best protection for a laptop is the same solution found in every telco CO - that cannot have damage. A properly earthed 'whole house' protector.

What is necessary so that a power strip protector does not cause a house fire? A properly earthed ‘whole house’ protector. Be concerned about sale promoters who even ignore the fire problem.
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Re: Do Power Strips & Laptops Mix?

Postposted on Tue Jun 05, 2012 4:32 pm

westom wrote:A protector is only as effective as its earth ground. As was understood even 100 years ago. Only solution always found in any facility that cannot have damage: proper earthing and a 'whole house' protector. Cost: about $1 per protected appliance. Best protection for a laptop is the same solution found in every telco CO - that cannot have damage. A properly earthed 'whole house' protector. What is necessary so that a power strip protector does not cause a house fire? A properly earthed ‘whole house’ protector. Be concerned about sale promoters who even ignore the fire problem.

I'm going to break my own popcorn rule for a moment. First, the whole-house surge protector is a great idea IF you have a spare 240V breaker position in your service panel and IF you both have access to your panel and rights to modify it. For many people living in multiple-unit residences as well as homeowners with fully-populated 100A or 150A service panels (still extremely common around these parts), they don't have that option either (a) at all or (b) without spending several thousand dollars on a panel retrofit. Second, the impedance difference between the neutral bus bar at the service panel and the ground connection at a wall outlet over 100 feet of a #12 copper service run will be roughly one-fourth of an Ohm, plus perhaps another Ohm or two of reactive impedance. This will not meaningfully cripple the ordinary operation of a MOV stack located at the end of that wire run.

Second, although MOV stacks can and have caught fire in worst-case failure scenarios, this is rare and unlikely to happen with any recently manufactured unit, as they are now required to have both overcurrent and thermal fuses in series with the MOV device. Most fires that start with a power strip involve loose connections or overloads, not the MOV device.
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Re: Do Power Strips & Laptops Mix?

Postposted on Tue Jun 05, 2012 5:15 pm

ludi wrote:I'm going to break my own popcorn rule for a moment. First, the whole-house surge protector is a great idea IF you have a spare 240V breaker position in your service panel and IF you both have access to your panel and rights to modify it. For many people living in multiple-unit residences as well as homeowners with fully-populated 100A or 150A service panels (still extremely common around these parts), they don't have that option either (a) at all or (b) without spending several thousand dollars on a panel retrofit. Second, the impedance difference between the neutral bus bar at the service panel and the ground connection at a wall outlet over 100 feet of a #12 copper service run will be roughly one-fourth of an Ohm, plus perhaps another Ohm or two of reactive impedance. This will not meaningfully cripple the ordinary operation of a MOV stack located at the end of that wire run.

Add to that the fact that many of us living in New England happen to own homes whose wiring was installed decades after the house was built in the first wave of electrification and are thus still 2-wire systems. I pull new 12/3 when & where I can, but most of my overhead lighting circuits will be groundless 2-wire until the day this place eventually burns down. Knob & tube is a common find in houses built before 1900 (and that's a large proportion of our housing stock).
It is one of the blessings of old friends that you can afford to be stupid with them. Ralph Waldo Emerson.
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Re: Do Power Strips & Laptops Mix?

Postposted on Wed Jun 06, 2012 7:57 am

ludi wrote: First, the whole-house surge protector is a great idea IF you have a spare 240V breaker position in your service panel and IF you both have access to your panel and rights to modify it. .

Those restrictions do not apply. A 'whole house' protector is often attached to the side of a breaker box. Or to the meter pan. Utility’s meter reader girl can even install one behind the meter. Everyone has numerous options to install a best and least expensive solution.

Impedance on a 100 foot 12 AWG wire is not that tiny. Wire resistance is well below 0.2 ohms. But wire impedance to a surge is more like 120 ohms. 120 ohms times a tiny 100 amp surge means the receptacle, during a surge, is at something less than 12,000 volts. Impedance is why a connection to earth must be so short (ie 'less than 10 feet'). Cannot be in conduit. Ground must not be that 12 AWG wire with too many sharp bends and splices. Impedance in a receptacle’s safety ground wire is too high.

If a ground wire from the breaker box to earth ground goes up over the foundation and down to earth, then protection is compromised. That ground wire must go through a foundation and down to earth. Wire length to single point earth ground is critical. Sharp bends over the foundation also increase impedance. Ground wire also should be separate from other non-grounding wires.

Impedance is why every incoming cable must connect so short to single point earth ground. Impedance is why separation between a protector and the appliance increases protection. Impedance is why telcos want their protectors separated up to 50 meters from that $multi-million switching computer.

Protection is about where hundreds of thousands of joules dissipate. Impedance is critically important to that process. Impedance is what an adjacent protector is not earthed.
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Re: Do Power Strips & Laptops Mix?

Postposted on Wed Jun 06, 2012 9:20 am

westom wrote:Read more lies and half truths from his 'cut and paste' replies.

My "lies and half truths" come from the IEEE and NIST.

Westom's cut and paste arguments come from his religious belief in earthing.

westom wrote:He even ignores that his own citation says. A plug-in protector (no earth ground) is "useless".

The NIST, of course, never says that.

Repeating what the NIST surge guide really says about plug-in protectors:
They are "the easiest solution".
And "one effective solution is to have the consumer install" a multiport plug-in suppressor.

He ignores what the citation says.

westom wrote:Meanwhile, if that protector does protection, then he quoted a number for each type of surge. If a ten year old can find them, then he must be nine years old. Reality: he cannot post what does not exist.

Does anyone but westom have trouble finding specs?

"Each type of surge" is more nonsense. Protectors have MOVs from H-G, H-N, N-G. That covers all possible power line surges.

westom wrote:He will post endlessly because he is paid to protect profits.

He will post endlessly because his belief in earthing has been challenged and cracks are appearing in his universe.

westom wrote:A protector is only as effective as its earth ground.

And westom's religious mantra. It is why westom believes plug-in protectors can not possibly work. The impedance of of the branch circuit ground wire is too high for earthing a surge.

Unfortunatly for westom the IEEE explains that plug-in protectors do not work primarily by earthing.

westom wrote:What is necessary so that a power strip protector does not cause a house fire? A properly earthed ‘whole house’ protector. Be concerned about sale promoters who even ignore the fire problem.

Funny, the IEEE and NIST don't say anything about protecting plug-in protectors.

Westom ignores that starting 1998 UL requires protectors to have thermal disconnects for failing MOVs.

And the "sales promoter" lie sprinkled into westom's rant.

westom wrote:Impedance on a 100 foot 12 AWG wire is not that tiny. Wire resistance is well below 0.2 ohms. But wire impedance to a surge is more like 120 ohms. 120 ohms times a tiny 100 amp surge means the receptacle, during a surge, is at something less than 12,000 volts.

Of course, at about 6kV there is arc-over at the service panel, and the arc drops to hundreds of volts. You won't get 12kV from a power line surge.

The impedance of the branch circuit then greatly limits the current that can reach a plug-in protector. That is why the energy that a MOV can absorb is only 35 joules, even with the largest power line surge that has any reasonable probability of occurring.

Of course westom ignores all the "engineering facts".

(A surge is a very short event. That means it has relatively high frequency current components. That means the impedance of wire is far more important than the resistance. The example in the IEEE surge guide starting page 30 has a 30 ft wire with 10,000V end-to-end.)

westom wrote:If a ground wire from the breaker box to earth ground goes up over the foundation and down to earth, then protection is compromised. That ground wire must go through a foundation and down to earth. Wire length to single point earth ground is critical.

The author of the NIST surge 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."

Worry about the length of the ground wire from cable and phone entry protectors to the common connection point on the power earthing system. The NIST surge guide suggests that the major cause of equipment damage is high voltage between power and phone/cable/... wires. An example of a entry protector ground wire that is too long is in the IEEE surge guide starting page 30.

Length of the wire to an earthing electrode is far less important. If you have a surge current to earth of 1,000A, and the only earthing electrode is a ground rod that has a near miraculous resistance to earth of 10 ohms, the building ground system will be 10,000A above 'absolute' earth potential. As a rule of thumb 70% of the voltage drop away from the rod is in the first 3 feet. The earth over 3 feet from the rod will be at least 7,000V from the building ground. The resistance of the wire just adds to the already high voltage you can get with a large surge.

If there is a strong surge the building 'ground' will float to a much higher potential relative to 'absolute' earth potential. You want all wiring in the building to float to the same high potential.


Still never seen - any source that agrees with westom that plug-in protectors do NOT work.

For real science read the IEEE and NIST surge guides. Both say plug-in protectors are effective..
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Re: Do Power Strips & Laptops Mix?

Postposted on Wed Jun 06, 2012 12:01 pm

Those restrictions do not apply. A 'whole house' protector is often attached to the side of a breaker box. Or to the meter pan. Utility’s meter reader girl can even install one behind the meter. Everyone has numerous options to install a best and least expensive solution.

That protector requires a breaker or other fusing device. Once you start installing devices upstream of the service panel you'll inherit most of the cost of installing an entire new subpanel. Also, I don't know who these delightful meter girls are that you deal with, but around here, we have Xcel Energy. I work with three engineers who were previously at Xcel, two of whom worked in the metering department, and they would fall over horse-laughing at these "easy and convenient" notions of yours. They had many fights with the internal bureaucracies just trying to get common-sense provisions implemented, and that was with an inside advantage. Random customers calling for service only get a rapid response if there is an actual outage, since the utility regulator will pound them for that. If the lights are still on, good luck.

I can show you an apartment complex I lived in a few years ago that was built in the mid-1970s, where every unit had an in-wall 60A panel with something like eight positions and no spares, and the metering was located out back next to a 250kVA service transformer. And this was some of the newer and better-managed apartment stock around here, unless you want to start spending six figures on late-80s and early-90s vintage townhomes, which I do not. There are no rights to modify any of the permanent electrical equipment in an apartment of that sort, and neither the apartment management nor Xcel Energy is going to entertain you for very long if you want to request expensive modifications for anything that isn't actually broken.
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