Automation system hit by lightning

[LarrylLix]

 

At the time I thought I was being smart because the clamping voltage is listed at 150v, but after reading this thread I'm noticing that the "let through rating" is 330/400/400, which doesn't sound so good (?).  What would have been a better surge strip to purchase?

Unfortunately those voltages are a fact of life. To protect a circuit with up to 132 vac allowed, a device has to be created higher than that or it may short out during normal operations.

A 150 vac device has to allow the peak voltage of the AC waveform so multipkybthe 150 by 1.414 to get 212 volts DC.

By the time some impedance and other factors are allowed for your 3-400 volts are probably just more truthfully than some other brands being most of them are probably using the same MOV devices anyway.

Never mind the troll factor here. This is very common for many to toss insults around when they cannot argue intelligently with somebody basically paraphrasing an accepted source like IEEE documents.

 

[mikefamig]

To understand what an spd is dealing with while trying to protect your equipment  you need to understand an AC current waveform. Voltage is constantly changing in an AC circuit and it has peaks and lows at different points in time. What we call 120 volts AC is actually 120 RMS AC volts. RMS stands for root mean squared and is a formula that is applied to a sample of many voltages occurring over a period of time to come up with 120vac RMS.
 
I am a DIY'er and I know that there are engineers and techs that can explain it but my point here is that your 120 volt AC home voltage may normally see peaks as high as 300 volts for very short periods of a second of time and you wouldn't even know it. Or at least that is my understanding of it.
 
Mike.

 

[westom]

I trust APC and would be happy with a power strip that they recommend but remember that any power strip is designed to be used to supplement a type2 and or type1 spd.

Why?  This company finally admitted to selling some 15 million protectors that must be removed immediately.  Catastrophic failure in their protectors was creating fires.  We had noted this problem years prevoiusly.  But since APC was selling near zero protectors with a massive profit margin, then the defect was unfortunately ignored:
http://www.cpsc.gov/en/Recalls/2014/Schneider-Electric-Recalls-APC-Surge-Protectors/
Companies with integrity would not create and would have immediately elimnated what was a simple, obvious, and dangerous defect.  APC did not.  Other and similar companies have that attitude: profits (not a better product) are more important.
 
 
Let-Through voltage:  First a protector is only one component of the 'system'.  Let-through voltage is about performance of that one part.  Clamping voltage measures an entire system.  APC will not provide a useful reply because APC protectors are missing other 'system' parts - ie single point earth ground.
 
All protectors conduct some current at all voltages.  (Current is the independent variable; voltage is only a dependent variable for those who remember high school math.)  Let-through voltage defines when current becomes significant while still well below what is necessary for effective protection.  As current increases, so does its voltage.  MOV manufacturers provide charts for this relationship.  As current increases, so does its voltage.  If protector parts are undersized, then a tiny surge current means voltage rises quickly to well over 900 volts.  A voltage this high is deemed completely unacceptable (for 120 volt protectors) by MOV manufacturers. And why fires happen.  These tiny (plug-in) protectors must be protected by something more robust such as a properly earthed 'whole house' protector.
 
No 'magic' voltage exists that a surge will rise to and not exceed. 120 volt protectors start conducting a tiny current at about 330 volts.  How much more current will cause a protector's voltage to be 900 volts?  That parameter says when a protectors will fail catastrophically (in rare cases create house fires).
 
Fire has long been a problem with plug-in protectors when not protected by a 'whole house' protector.   Let-through voltage only applies to a protector.  Actual clamping voltage is higher as defined by all parts of that protection 'system'.   Protection is summarized by the entire clamping voltage.  That voltage can be excessive for a small current when a protector does not have a low impedance (ie less than 10 foot) connection to single point earth ground.  Earth ground is critical in determining a voltage that is relevant.  And so the expression, "a protector is only as effective as its earth ground".
 
Why is a 300 volt transient acceptable?  120 volt electronic design standards (long before PCs even existed) defined no damage even with 600 volt spikes.  Effective protectors conduct a massive current (ie 20,000 amps) without creating a voltage that high.  Another number that says why informed consumers properly earth a 'whole house' protector.

 

[mikefamig]

With all this talk of lightning strikes it occurred to me to that some of us need protection more than others. Check thisout, it's a list of annual lightning flashes by state.
 
http://www.lightningsafety.noaa.gov/stats/05-14_Flash_Density_State.pdf

 

[mikefamig]

Why?  This company finally admitted to selling some 15 million protectors that must be removed immediately.  Catastrophic failure in their protectors was creating fires.  We had noted this problem years prevoiusly.  But since APC was selling near zero protectors with a massive profit margin, then the defect was unfortunately ignored:
http://www.cpsc.gov/en/Recalls/2014/Schneider-Electric-Recalls-APC-Surge-Protectors/
Companies with integrity would not create and would have immediately elimnated what was a simple, obvious, and dangerous defect.  APC did not.  Other and similar companies have that attitude: profits (not a better product) are more important.
 
 
Let-Through voltage:  First a protector is only one component of the 'system'.  Let-through voltage is about performance of that one part.  Clamping voltage measures an entire system.  APC will not provide a useful reply because APC protectors are missing other 'system' parts - ie single point earth ground.
 
All protectors conduct some current at all voltages.  (Current is the independent variable; voltage is only a dependent variable for those who remember high school math.)  Let-through voltage defines when current becomes significant while still well below what is necessary for effective protection.  As current increases, so does its voltage.  MOV manufacturers provide charts for this relationship.  As current increases, so does its voltage.  If protector parts are undersized, then a tiny surge current means voltage rises quickly to well over 900 volts.  A voltage this high is deemed completely unacceptable by MOV manufacturers and why fires happen.  These tiny (plug-in) protectors must be protected by something more robust such as a properly earthed 'whole house' protector.
 
No 'magic' voltage exists that a surge will rise to and not exceed. 120 volt protectors start conducting a tiny current at about 330 volts.  How much more current will cause a protector's voltage to be 900 volts?  That parameter says when a protectors will fail catastrophically (in rare cases create house fires).
 
Fire has long been a problem with plug-in protectors when not protected by a 'whole house' protector.   Let-through voltage only applies to a protector.  Actual clamping voltage is higher as defined by all parts of that protection 'system'.   Protection is summarized by the entire clamping voltage.  That voltage can be excessive for a small current when a protector does not have a low impedance (ie less than 10 foot) connection to single point earth ground.  Earth ground is critical in determining a voltage that is relevant.  And so the expression, "a protector is only as effective as its earth ground".

 
Because they are leaders in the field and I don't live to re-invent the wheel.

 

[mikefamig]

Westom
 
Given a modern home built to NEC code with whole house type 2 surge protection - which spd power strip do you recommend assuming that it is properly installed to a well grounded outlet?
 
Mike.

 

[dementeddigital]

With all this talk of lightning strikes it occurred to me to that some of us need protection more than others. Check thisout, it's a list of annual lightning flashes by state.
 
http://www.lightningsafety.noaa.gov/stats/05-14_Flash_Density_State.pdf

 
Here is a nice map, too.
 
http://www.lightningsafety.noaa.gov/stats/97-11Flash_Density_miles.png

 

[LarrylLix]

 
Here is a nice map, too.
 
http://www.lightningsafety.noaa.gov/stats/97-11Flash_Density_miles.png

Interesting that half of California doesn't hardly know what lightning is.

 

[westom]

Westom
 
Given a modern home built to NEC code with whole house type 2 surge protection - which spd power strip do you recommend assuming that it is properly installed to a well grounded outlet?

 
No plug-in (power strip)  protector is earthed.  Wall receptacle safety ground clearly is not earth ground for many reasons.  Including one posted repeatedly: low impedance (ie less than 10 foot).
 
Listed previously were many manufacturers of integrity ( http://cocoontech.com/forums/topic/29367-automation-system-hit-by-lightning/page-4#entry246391 ) that provide effective 'whole house' protectors.  In every case, the protector has a dedicated wire for that low impedance (ie wire has no sharp bends) connection to earth.  APC was not listed - does not sell them.
 
Plug-in protectors are not rated to be that close to earth ground - for human safety reasons.  Type 1, 2, 3  define that that human safety issue.  If it cannot be connected close to (low impedance) to earth, then what is it protecting from?  Not from typically destructive surges. 
 
NEC code may or may not provide sufficient earthing (in articles completely different from where safety ground is defned).  NEC is only about human protection.  Protection is about transistor protection.  A NEC required earth ground may need be upgraded to also provide transistor protection.  Again, this critical expression applies - low impedance (ie less than 10 feet).
 
A minimal 'whole house' protector is 50,000 amps (with that always required earth ground connection).  It must be at a service entrance to make that low impedance connection.
 
APC is famous for profit margins and advertising.  Take a $3 power strip.  Add some ten cent parts.  Sell it for $25 or $50 with plenty of advertising.  APC is not found in venues where surge damage cannot happen.  In fact, an employee might be fired in some high reliability facilities for installing that company's near zero product.   APC is an industry leader in selling near zero protectors to naive consumers.
 
Monster also has a long history of identifying scams.  Then selling a similar product (ie with more expensive paint) for $80 or $100.  That Monster is electrically similar to the APC and to a protector selling in Walmart for ten dollars.  APC and Monster were clearly not defined in a list of companies with integrity.  Why did APC continue to sell protectors that were creating house fires due to a glaring and obvious defect?  Why did they sell 15 million of them?  This is a responsible industry leader?  Or a leader among companies known for little integrity and obscene profit margins?
 
Plug-in protectors do not claim to protect from typically destructive surges. As made glaring obvious by what does not exist - a low impedance connection to single point earth ground.  It even absorbs so few joules - ie hundreds or a thousand.

 

[westom]

Interesting that half of California doesn't hardly know what lightning is.

 
Outside of San Francisco,  lightning literally caused an entire radio station to explode.  A transformer that connected 33,000 volts to 240 distribution was not properly earthed.  Lightning created a plasma path (a direct connection) from 33,000 volts to 240 volts.  That transformer even exploded with so much force that only tiny pieces remained.
 
Lightning (even in California) does not have energy to create such damage.  Damage was created by what is called in the industry a 'follow through current'.  Energy that did most damage was from the utility's 33,000 volt supply.  A fault was created because that transformer' earth ground (the 'primary' surge protection layer) was missing.

 

[mikefamig]

Interesting that half of California doesn't hardly know what lightning is.

 
I think that much of California hardly knows what rain is. We are very luck y here in the Northeast as we get relatively little destructive weather including lightning. We see an occasional hurrican but even they are usually worn thin by the time they make it to the north atlantic.

 

[mikefamig]

No plug-in (power strip)  protector is earthed.  Wall receptacle safety ground clearly is not earth ground for many reasons.  Including one posted repeatedly: low impedance (ie less than 10 foot).
 
Listed previously were many manufacturers of integrity ( http://cocoontech.com/forums/topic/29367-automation-system-hit-by-lightning/page-4#entry246391 ) that provide effective 'whole house' protectors.  In every case, the protector has a dedicated wire for that low impedance (ie wire has no sharp bends) connection to earth.  APC was not listed - does not sell them.
 
Plug-in protectors are not rated to be that close to earth ground - for human safety reasons.  Type 1, 2, 3  define that that human safety issue.  If it cannot be connected close to (low impedance) to earth, then what is it protecting from?  Not from typically destructive surges. 
 
NEC code may or may not provide sufficient earthing (in articles completely different from where safety ground is defned).  NEC is only about human protection.  Protection is about transistor protection.  A NEC required earth ground may need be upgraded to also provide transistor protection.  Again, this critical expression applies - low impedance (ie less than 10 feet).
 
A minimal 'whole house' protector is 50,000 amps (with that always required earth ground connection).  It must be at a service entrance to make that low impedance connection.
 
APC is famous for profit margins and advertising.  Take a $3 power strip.  Add some ten cent parts.  Sell it for $25 or $50 with plenty of advertising.  APC is not found in venues where surge damage cannot happen.  In fact, an employee might be fired in some high reliability facilities for installing that company's near zero product.   APC is an industry leader in selling near zero protectors to naive consumers.
 
Monster also has a long history of identifying scams.  Then selling a similar product (ie with more expensive paint) for $80 or $100.  That Monster is electrically similar to the APC and to a protector selling in Walmart for ten dollars.  APC and Monster were clearly not defined in a list of companies with integrity.  Why did APC continue to sell protectors that were creating house fires due to a glaring and obvious defect?  Why did they sell 15 million of them?  This is a responsible industry leader?  Or a leader among companies known for little integrity and obscene profit margins?
 
Plug-in protectors do not claim to protect from typically destructive surges. As made glaring obvious by what does not exist - a low impedance connection to single point earth ground.  It even absorbs so few joules - ie hundreds or a thousand.

 
To sum it up you can not recommend a point-of-use spd and that you consider a point-of-use spd useless which disagrees with the IEEE document that was referred to earlier in this message thread. With all due respect my money's on the IEEE.
 
Have you read this?
 
http://lightningsafe.../IEEE_Guide.pdf
 
 
 
Mike.

 

[dementeddigital]

Thanks!  If someone can name a better one, please do.  Otherwise, I'm probably going to get it installed this summer.  FWIW, I think this thread would have gone better if folks had identified specific products they recommended instead of leaving it to generalities.  At the end of the day both I and others need a concrete list of things to buy, and it's nice to have that vetted by a group of knowledgeable people like those here on cocoontech.
 
To that end, two years ago I purchased a couple of these surge protector strips:  https://www.tripplite.com/protect-it!-8-outlet-surge-protector-10-ft-cord-3240-joules-modem-coax-ethernet-protection-rj45~TLP810NET/
At the time I thought I was being smart because the clamping voltage is listed at 150v, but after reading this thread I'm noticing that the "let through rating" is 330/400/400, which doesn't sound so good (?).  What would have been a better surge strip to purchase?

 
I don't have much of an opinion about power strips, but here is an article which looks at a few different ones.
 
If you have a type 1 or type 2 SPD in place, that device is going to greatly limit the voltage that everything in the house experiences during a surge.  Because of this and wire inductance, the plug-in SPDs are going to experience a much lower energy level during the surge, too.  The electronics in your house can also tolerate some overvoltage for some time.  They typically have some amount of protection inside, as well as a voltage input range which should cover normal high-line voltages.
 
At the end of the day, I wouldn't worry too much about the specs on the plug-in devices if you have a type 1 or type 2 SPD.  You might want to select one which disconnects the load in the event of damage, and also get one from a known manufacturer, like you mentioned.
 
The only thing that I WOULD worry about with the point-of-use SPDs is protecting all of the paths to your electronics.  Anything which has wires connected to places other than the AC outlet may have another path for a surge to enter.  If one path (like the AC wiring) is protected and the other is not, then one connection will see a surge while the other will not.  When this happens, the electronic device can become the path for the surge, causing damage.  Things like a TV with a coax cable connected, a computer with an Ethernet cable, a cordless phone connecting to the phone line and AC power, should be looked at. 
 
Just like with the power wiring surge protection strategy we've been thrashing here, the "other" wires should be protected where they enter the house (preferably at the power service entrance), and they should have their own SPD connected to Earth ground.  If they enter the house somewhere other than at the power service entrance and are protected there, then you should bond that ground to the electrical service ground so that they are at the same potential during a surge.  They can also be protected again at the point of use.  In the case of a TV, I would get a power strip with built-in surge protection for both the AC wiring and the coax.
 
One of the guys I work with just had a lightning surge at his house and lost his air conditioner.  They think that the surge entered the system via the control wiring.  I don't have those protected on my house either.  Note to self...

 

[LarrylLix]

 
Outside of San Francisco,  lightning literally caused an entire radio station to explode.  A transformer that connected 33,000 volts to 240 distribution was not properly earthed.  Lightning created a plasma path (a direct connection) from 33,000 volts to 240 volts.  That transformer even exploded with so much force that only tiny pieces remained.
 
Lightning (even in California) does not have energy to create such damage.  Damage was created by what is called in the industry a 'follow through current'.  Energy that did most damage was from the utility's 33,000 volt supply.  A fault was created because that transformer' earth ground (the 'primary' surge protection layer) was missing.

Not quite a good diagnosis. Lightning jumping from one winding into another winding across the winding insulation is not due to any lack of grounding.

Distribution transformers may occasionally have lightning protection installed at it's primary bushings to prevent lightning surges from breaking down internal insulation but a direct hit from lightning is not stopped by lightning arresters or interwinding insulation. Most of the equipment explodes from the millions of joules and/or voltage avalaible due to the lightning hit. The lightning protector usually explodes at this point and needs to be replaced with the transformer and equipment downstream on that same line. Home surge protection close by doesn't do much with close hits no matter how good the grounding is done. Even the step potential rise destroys things in the building finding multiple ground paths.

Agreed, the power flow following the carbonised insulation materials or the ionised air from the lightning arc is definitely a major factor in the damage caused by lightning. This is what the recloser schemes on, especially, rural grid distribution circuits is all about.

When a lightning hit strikes a transmission line the arc finds earth somewhere along the line, usually at weaker points, like insulators on the poles. To avoid grid power following and creating damage, or more damage, most recloser schemes will trip the inline breaker contacts open and then will reclose immediately. This is an attempt to stop this phenomenem by causing a 0.1-0.5 second outage to the loads.

This is usally followed by various engineers concepts of what to do next. Most I have dealt with, will then "tougher" the overcurrent protection and if the sensing still sees the fault then the breaker opens again, but waits about 1 second before closing the breaker again.

This can be followed by a few more longer outages in an attempt to have the customers stay out and a line truck service call has to be made to refuse something many kilometres out in the country and hours of outage for customers. Of course the line has to be manually patrolled to find exploded insulators, burnt transformers, or downed conductors.

After a designed number of recloses the protection may be toughened past the circuit fuse blow curve so that further sensing of the same fault disturbance will blow the line fuse that controls a much larger area of customers.

The whole thing is dfefinitely an art and a science and a bit of luck at times for some events.

 

[westom]

To sum it up you can not recommend a point-of-use spd and that you consider a point-of-use spd useless which disagrees with the IEEE document that was referred to earlier in this message thread. With all due respect my money's on the IEEE.

 
With disrespect for your IEEE citation, you again contradict what both I and IEEE have said repeatedly.  IEEE and I are in complete agreement.  You did not read what  the IEEE says.  Time to admit to brainwashing by APC advertising.   Why did APC sell some 15 million protectors knowing those could create fires?  You called this a company of integrity?  Does that mean you are a honest person?
 
Figure 8.  A plug-in protector earthed a surge 8000 volts destructively via some nearby appliance.  It did what it claims to do.  Figure 8 is in your own citation - that you did not read.  Why dioyou not quote specific examples? You cannot quote what you really did not understand.
 
When did I say that plug-in protector is useless?  When a 'whole house' solution is not implemented.  Even your IEEE citation says same - even in figure 8.   Why did you ignore what I said?  Why do you claim I said only what you wanted to hear?  Again - hoping if I say it enough times, then you might grasp it.   A plug-in protector may do an additional 0.2% of the protection is part of a 'whole house' solution.  If that 'whole house' solution does not exist, then figure 8.  That near zero protector may even earth a surge 8000 volts destructively via nearby appliances.
 
A 'whole house' solution does maybe 99.5% to 99.9% of the protection. Reality is that easy.  If that 'whole house' solution does not exist, then a plug-in protector can even compromise robust protection inside appliances.  Might even earth a surge 8000 volts destructively via those nearby appliances. How many times is figure 8 mentioned before you will finally read it?
 
I never said plug-in protectors are useless.  Only you make that claim.  Plug-in protectors can make appliance damage easier if a 'whole house' solution does not exist.  Another IEEE paper was and is quoted again hoping you will finally read and comprehend the facts: [

... objectionable difference in reference voltages ... occur even when or perhaps because, surge protective devices are present at the point of connection of appliances.

 
Why do you try to put words in my mouth.  Why do you not even read your own citation?  What does a plug-in protector do when the 'whole house' solution is not implemented?  How many more times must I post this?  Figure 8.  8000 volts destructively via an adjacent appliance.
 
To sum it up, you fail to read your citations.  A plug-in protector may do 0.2% additional protection when part of a 'whole house' solution.  May do 8000 volts damage when not. - figure 8.  How much easier can I make this?