Automation system hit by lightning
- Thread starter kurtmccaslin
- Start date
Those who are technically incapable of solving problems or learning something new must do what they only understand - attack the messenger.mikefamig said:
Others who prefer to learn can appreciate why the OP had damage. Wires entered a structure without making a low impedance connection to single point earth ground. That low impedance (ie less than 10 foot) connection to earth is made by a hardwire (a direct connection) or via a 'whole house' protector. Then all types of surges (including and not limited to direct lightning strikes) need not do appliance damage.
Same well proven concept protects structures. Ben Franklin also connected lightning to what does protection - earth ground. Then typically destructive surges (lightning) need not do structure damage.
Any wire that interconnects two structures must have a 'whole house' solution at both ends of that wire. The solution, well understood even 100 years ago, exists in every town. However, if a homeowner does not learn it, then any resulting damage is directly traceable to that homeowner's mistake.
Reality cannot be repeated enough times when the naive want to obfuscate reality with myths, lies, and personal cheapshots.
So a SPD on the field cabling with a quick response time and quick clamp to ground on the field data cabling between the security panel and the expansion in the remote building, in addition to a service SPD is what you're suggesting now?
I believe that was suggested at least 4 times and negated by you Mr. Westom, stating that an EG is the solution. So what would be the suggestion for connecting the system data cabling to the EG? Wouldn't that be a Ditek or Edco type device? Clamp the surges to ground before the equipment.
I believe that was suggested at least 4 times and negated by you Mr. Westom, stating that an EG is the solution. So what would be the suggestion for connecting the system data cabling to the EG? Wouldn't that be a Ditek or Edco type device? Clamp the surges to ground before the equipment.
Here is an excellent guide from the IEEE on the proper ways to provide surge protection from lightning as well as other sources, such as utility system problems.
http://lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf
It's written by 5 experts on lightning and surge protection. It's a long paper, but worth reading. It even explains why power strip surge protectors are worth having. I recall someone saying they weren't necessary as they provided little value.
http://lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf
It's written by 5 experts on lightning and surge protection. It's a long paper, but worth reading. It even explains why power strip surge protectors are worth having. I recall someone saying they weren't necessary as they provided little value.
westom said:
Good example of the naivety of the author. Quite sexist and sounding like one of the presidential candidates (sorry for the political sidebar). And at least in our region, electrical meter reading has been automated for MANY years.
....Couldn't resist the commentary...
RAL said:
I haven't read the entire doc yet but lots of info here, thanks.
Here's a quote that was enlightening to me. It explains why I had and still have such a hard time choosing and spd:
The voltage peak to which an SPD limits an incoming surge has been given many
different names, including “protection level”, “Suppressed Voltage Rating”
(SVR), “surge response voltage”, “let through voltage”, “clamping voltage”,
“surge residual”, and “surge remnant”. Technically, the proper term is “surge
residual”, that is, the voltage remaining after a surge protector has acted to limit a
surge.
Mike.
WESTOM Do you agree with this statement:
Effectiveness of an SPD is strongly affected by the installation. The installation is
fully under the control of the SPD purchaser and should not be treated lightly.
The primary issues that need to be addressed are grounding, lead length, and over-
current protection.
??
Effectiveness of an SPD is strongly affected by the installation. The installation is
fully under the control of the SPD purchaser and should not be treated lightly.
The primary issues that need to be addressed are grounding, lead length, and over-
current protection.
??
mikefamig said:
What was I saying all along - from the very beginning? Primary issue of grounding was repeatedly defined by "single point earth ground" and 'layers of protection'. What defines each 'layer of protection'? Earth ground. What must harmlessly absorb hundreds of thousands of joules? Earth ground. How many even asked about the 'primary' protection layer after challenge to so many times? No one. Those who deny subjectively fully ignore grounding. "Therefore, an evaluation of the service entrance grounding system at the time of the SPD installation is very important." Who has been saying this repeatedly?
Primary issue of lead length was repeatedly defined by the "low impedance (ie less than 10 feet). And other parameters that would create excessive impedance between the surge and earth. "An effective, low-impedance ground path is critical for the successful operation of an SPD." A protector can only be as effective as the quality of that connection; including lead length. Response time of a protector becomes excessive if lead length is too long. "Surge residual" can be excessive if lead length is too long.
Primary issue of overcurrent protection was repeatedly defined by spec numbers. How much current must an effective protector conduct? A minimal 'whole house' protector must be at least 50,000 amps. Since effective protectors even earth direct lightning strikes - and remain functional.
What is different between that subjective statement and what I have posted repeatedly? I said same - with numbers. How many times does that IEEE brochure discuss earth ground? 250+ times? A protector is only as effective as its earth ground.
That means an SPD is strongly affected by its installation. World's best protector can be useless if not properly installed - not properly earthed. What do plug-in protectors not have and will not discuss? Earth ground.
Damage from surges including direct lightning was so routine that damage is considered a human mistake - fully under the control of the installer. How many others (who?) have described proper installation - with numbers? None?
dementeddigital
Active Member
mikefamig said:
I'm an electrical engineer, and I can say that some of the details can get a little strange. The way people use some terms interchangeably doesn't help at all.
After peeling into this a bit, I would conclude that all of the terms listed above are not referring to exactly the same thing, even though they are very often used interchangeably.
For example:
"Clamping voltage" is generally used to indicate the voltage where the SPD begins diverting or conducting energy.
"Let-through voltage" is the residual transient voltage that would appear across equipment after the SPD has operated. It is important to remember that the "let-through" voltage is the sum of the voltage drop across the surge protector itself plus the voltage drops that appear across the wiring that connects the protector to the power lines. The protector clamping voltage is only one part of the let-through voltage. Several factors can influence let-through voltage including the lead length, spacing, and twist during installation.
I curled up with UL1449, and they only use "let-through" when referring to current or energy - not voltage. I wouldn't overthink it too much, though. You basically want an SPD with a UL mark which has a high energy rating (joules), a high current rating (amps), a fast response time (nsec), and the lowest protection voltage suitable for the circuit on which it is used. Then you want to install it with the shortest possible wire length (twisted together if they run more than about 8 inches). You also want to make sure that you have a properly installed ground rod with a secure connection (as short as possible) between the ground rod and your electrical system (and thus the SPD).
The quality of the installation will heavily influence the performance. A mid-grade SPD well installed will likely outperform a high-end device which is poorly installed (long wire lengths, etc.) The high-end device will generally have a longer service life, though. The high energy and current rating will allow the device to take larger surges. It also equates to the usable life of the surge protector. Bigger numbers here generally equate to longer life.
dementeddigital
Active Member
mikefamig said:
YES!
NeverDie
Senior Member
dementeddigital said:
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 think htat you may be misunderstanding the term "let through".
This quote from UPC explains it fairly well:
Let-Through Voltage is actually the difference between the effective clamping voltage and the peak AC voltage. For example, a UL 330V rating indicates that the let-through voltage to the protected equipment is < or = 330V minus 169 Volts peak (for a standard 120 VAC power).
http://www.apc.com/us/en/faqs/FA158814/
This quote from UPC explains it fairly well:
Let-Through Voltage is actually the difference between the effective clamping voltage and the peak AC voltage. For example, a UL 330V rating indicates that the let-through voltage to the protected equipment is < or = 330V minus 169 Volts peak (for a standard 120 VAC power).
http://www.apc.com/us/en/faqs/FA158814/
This is an interesting article about what happens when the spd power strip fails:
http://www.computerworld.com/article/2472189/network-hardware-solutions/a-surge-protector-that-doesn-t-protect.html
http://www.computerworld.com/article/2472189/network-hardware-solutions/a-surge-protector-that-doesn-t-protect.html
NeverDie said:
It seems to me that there is a lot of confusion involved in choosing an spd. I've read that different manufacturers use different methods to test their devices and use different terminology to describe their outcomes. I'd love to hear someone explain it in plain English.
Just after I learned that let through voltage is the voltage that is not clamped to earth and does get through to your equipment I found the APC article that explains that it is actually the difference between the effective clamping voltage and the peak AC voltage.
Now I don't know what to believe.
Mike.
EDIT
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.
