lightning protection both ends of cable

[Soundy 1]

by the time he has paid and installed equipment to protect it. ... it will of been cheaper to replace the dvr than what it was to try and protect.

Cost of installing pvc pipe was probably much more than the cost of a superior and earthed protector.

 

Maybe, but the chance of damage to the wire by sun, weather, birds, animals, or other environmental factors is about a million times higher than the chance of lightning damage.

[bud--- 0]

In every case, a protector has that earthing wire.

Westom has a religious belief (immune from challenge) that surge protection must directly use earthing. Thus in his view plug-in protectors (which are not well earthed) can not possibly work.

 

The IEEE guide explains (starting page 30) that plug-in protectors do not work primarily by earthing. They work by limiting the voltage on all wires (power and signal) to the common ground at the protector. The guide explains earthing occurs elsewhere. Westom ignores the explanation (and everything else that does not fit his belief in earthing).

 

Retail protectors such as Belkin or Tripplite do not provide earthing and will not discuss it.

They don't discuss earthing because plug-in protectors do not work primarily by earthing.

 

How does its 1400 joules (actually 460 joules and never more than 930 joules) magically absorb hundreds of thousands of joules? It doesn't. A joules number is provided only due to UL safety requirements.

Nonsense. It is only magic for westom.

 

And plug-in protectors do not work by absorbing surges (but they absorb some energy).

 

The author of the NIST surge guide looked at the amount of energy that might be absorbed in a plug-in protector. He used branch circuits 10 m and longer. The power service surge was up to 10,000A. (That is the maximum that has any reasonable probability of occurring - based on a 100,000A strike to a utility pole adjacent to the house with typical urban overhead distribution). The maximum energy absorbed was a surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less. A plug-in protector with high ratings (like 1400 joules) and wired correctly is likely to protect from even a very close, very strong lightning strike.

 

Wired correctly means all wires leaving a set of protected equipment (power, phone, cable, camera) go through the plug-in protector.

 

There are a couple reasons the energy was so small if anyone is interested.

 

A sales promoter was asked for those numbers. And again refused to provide what does not exist.

Two of westom's favorite lies.

 

A protector is only as effective as its earth ground

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

 

Like - the IEEE surge guide explains plug-in protectors do not work primarily by earthing.

 

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

[shropna 0]

westom, great tips.

Actually, all lightening protection works as well like soap to protect from AIDS, as example . If we have direct lightening.

Best way is avoid current in "loop", caused power lines, not correct grounding, etc.....

As an example, surge protector, placed near camera, is grounded to direct ground pole.

If we have strong lightening near this place, voltage difference between "center" and "camera" grounding points will be to high, an current will occur to all data lines....

If we not connect surge protection unit near camera, or, do not use different grounding points, current, caused lightening, will not appear.

So, "Star" wiring configuration is the main protection.

Surge protectors are just "additional" protection....

[westom 0]

If we have strong lightening near this place, voltage difference between "center" and "camera" grounding points will be to high, an current will occur to all data lines....

As demonstrated by that professional's application note, the building has an earth ground. A tower has a different ground. You apparently have same - a building ground and a camera ground. A direct lightning strike to either may act like a lightning rod connected to electronics at the other end. The app note demonstrated how both earth grounds avert that damage:

http://www.erico.com/public/library/fep/technotes/tncr002.pdf

 

Building and tower grounds in that app note are electrically equivalent to your building and camera. Each is treated as if a separate structure. Any wire inside any incoming cable must first connect short to the camera's ground before connecting to the camera. Each and every wire must also make a low impedance (short) connection to the building's center ground before entering. Then direct lightning strikes and other lesser transients need not cause damage at either end. Any one conductor violating that 'short as possible to ground' rule explains damage.

 

If an incoming wire connects direct to earth with no protector, then protection is best. But video signals would be disrupted. A protector tries to do what copper wire does better. Without disrupting video signals. The only purpose of a protector. To make a connection to earth when a copper wire cannot make that connection. A protector only does what a copper wire would otherwise do better. Connect hundreds of thousands of joules harmlessly to earth. Otherwise a protector must either absorb that energy or do nothing.

 

Telcos also do what protects that camera and building electronics. Money is not wasted on protectors without earthing, such as the Belkin or Tripplite. If lightning causes damage, then an installer searches for and corrects his installation mistake. An investigation that begins with the only item that must always exist to have protection - earth ground. In your example, camera and building are treated as two separate structures – each with its own single point earth ground.

[bud--- 0]

Building and tower grounds in that app note are electrically equivalent to your building and camera. Each is treated as if a separate structure.

The OP did not have different buildings. He had a camera at a distant point on the same building. Treating them as separate structures is not practical. You want an added earthing system at the camera location? How are you bonding it to the main building earthing system?

 

Connect hundreds of thousands of joules harmlessly to earth. Otherwise a protector must either absorb that energy or do nothing.

And in westom's opinion plug-in protectors do nothing. Complete nonsense.

 

Plug-in (and service panel) protectors do not work by absorbing a surge. And as I wrote in a previous post the amount of energy absorbed in the process of protecting is very small - even with a very near very strong lightning strike.

 

Telcos also do what protects that camera and building electronics. Money is not wasted on protectors without earthing, such as the Belkin or Tripplite.

Gee - why wouldn't a telco use a plug-in protector to protect a hard wired high amp switch with thousands of phone circuits that would have to go through the protector?

 

An investigation that begins with the only item that must always exist to have protection - earth ground.

The point being that plug-in protectors, which are not well earthed, can not possibly work.

 

Unfortunately for westom the IEEE surge guide explains plug-in protectors work primarily by limiting the voltage between all wires (power and signal) and the ground at the protector.

 

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

[HeadsUp 0]

by the time he has paid and installed equipment to protect it. ... it will of been cheaper to replace the dvr than what it was to try and protect.

Cost of installing pvc pipe was probably much more than the cost of a superior and earthed protector.

 

Maybe, but the chance of damage to the wire by sun, weather, birds, animals, or other environmental factors is about a million times higher than the chance of lightning damage.

 

Yes . damage from mice , rats , weathering , birds and UV rays were the main reason for using conduit

 

I have lost equipment from lightning once , and after installing a pannamax unit on the mains supply we lost nothing from 3 subsequent lightning strikes , one of which was so close to the house that i felt static electricity in the air around me causing my hair to stand up

 

when this occurred i was sitting in front of the computers and not one of them showed the slightest sign of surge

 

the pannamax unit mentioned protects the mains power , phone line and TV coax from the antenna

it was well worth the $ 290 i paid for it.

 

Edited December 29, 2011 by Guest

[HeadsUp 0]

My question is . can i use two lightning surge protectors on the same cable , one at the camera and one at the DVR ?

 

Best protection is a wire connected directly to earth ............... So an ethernet protector connects all eight wires as short as possible to protection - earth. Only then does lightning use a path that causes no damage.............................................Your ethernet wire must first route down and connect to single point earth ground before rising back up to enter the building.

Other solutions also exist.

 

thanks everyone for the many replies

 

Westom , how do you connect all 8 wires of an ethernet cable to earth without shorting them out ?

 

as far as protection goes , i do know from experience that unearthed suppression does work , presumably by having proprietary components to limit voltage or current flow in them on every conductor and hence a less attractive path. ( see my previous reply to soundy above )

 

So , protection has to either provide a better path for the lightning to take to ground , and / or probably also create increased resistance to conductivity towards the protected device.

 

From memory the pannamax device i have was rated to 100,000 volts and " X" joules and had a connected equipment warranty.

 

however i have ordered the following surge protector and some others which are only el-cheapo varieties - they are all i could find after searching local suppliers so the jury is out if they will do anything . note the earth wire is a light gauge but hopefully for my DVR it will work successfully by internal suppression as mentioned above.

 

http://www.ebay.com.au/itm/280779999041?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

[westom 0]

however i have ordered the following surge protector and some others which are only el-cheapo varieties - they are all i could find after searching local suppliers so the jury is out if they will do anything . note the earth wire is a light gauge but hopefully for my DVR it will work successfully by internal suppression as mentioned above.

The protector is for BNC (not for Cat5 Ethernet). Rated for 5000 or 10,000 amps. It will easily earth such surges if its ground wire makes a low impedance (ie 'less that 3 meter') connection to earth. Unfortunately a typical lightning strike is 20,000 amps.

 

Wall receptacle safety ground is not earth for many reasoning including a number - 'less than 3 meters'. Protectors are rated in current because a protector must connect that current low impedance to earth. Then a surge creates no high voltage.

 

If a $290 protector did protection, then a long list of other appliances (including the furnace, air conditioner, etc) were destroyed. If not, then the protector was, at best, doing what was done by protection already inside every appliance.

 

Normal is to feel a nearby lightning strike while nothing is damaged. Because protection already inside every appliance makes that E-M field irrelevant. For example, lightning struck a building's lightning rod. That maybe 20,000 amps was on a wire to earth and less than four feet from an IBM PC. The PC did not even blink due to protection standard in all electronics even that long ago when internal protection was less robust. Protection inside all appliances is that good.

 

Your concern is a current that might use appliances (ie video server) as a connection to earth. That type surge can overwhelm existing internal protection. For a Cat5 wire that exposed, protector current rating should probably be higher.

 

However, other solutions also exist.

[westom 0]

Westom , how do you connect all 8 wires of an ethernet cable to earth without shorting them out ?

Protection means energy is connected to and harmlessly dissipates in earth. Best protection is provided by a ground wire. But an Ethernet wire cannot carry signals if earthed directly by ground wire. Effective protector does what protectors did even in the late 1800s when first patented. Protector makes a connection from each of eight wires to earth so that low voltage (single digit) signals on a Cat5 wires are not disrupted.

 

If energy connects low impedance to earth, then it does not go hunting for earth destructively via appliances. Then superior protection inside every appliance is not overwhelmed. Protection from a destructive type of surges is always about where that energy is connected and dissipated. Protection means a protector connects all eight Cat5 wires to earth. A relevant current number was discussed in the previous post.

 

Of course, other solution are available.

[bud--- 0]

The protector is for BNC (not for Cat5 Ethernet). Rated for 5000 or 10,000 amps. It will easily earth such surges if its ground wire makes a low impedance (ie 'less that 3 meter') connection to earth. Unfortunately a typical lightning strike is 20,000 amps.

When lightning strikes it typically has multiple paths to earth. As I wrote in a previous post the maximum surge current that has any reasonable probability of occurring is 10,000A per hot service wire. That is based on a 100,000A lightning strike to an adjacent utility pole in typical overhead distribution. There is a reference to the 10,000A figure in the IEEE surge guide. Note this is worst case, not "typical".

 

In US systems, at about 6,000V there is arc-over from service panel bussbars to the enclosure. When the arc stabilizes the voltage is hundreds of volts. Since the enclosure is connected to the earthing system that dumps most of the surge energy to earth. The same should happen in other systems, with different arc-over voltage.

 

You simply can't have anything like a 10,000A surge current past the service panel (unless you have a direct strike to the building).

 

Wall receptacle safety ground is not earth for many reasoning including a number - 'less than 3 meters'.

By which westom is saying that plug-in protectors can not possibly work.

 

But the IEEE surge guide explains how they work. It is not primarily by earthing the surge.

 

Protectors are rated in current because a protector must connect that current low impedance to earth. Then a surge creates no high voltage.

Nonsense.

 

Protectors are rated in current because that is the maximum single event current that puts the protection elements at defined "end of life". A surge current rating is exactly equivalent to a joule rating. (The 100,000 rating from HeadsUp would be amps, not volts.)

 

For an effective protector the surge current rating will be far above any surge current that it will get in a single event (just like the joule rating will be far above what the protector gets in a single event).

 

If a $290 protector did protection, then a long list of other appliances (including the furnace, air conditioner, etc) were destroyed.

Plug-in protectors, obviously, protect what is connected downstream from them.

 

The NIST surge guide suggests that most equipment damage is caused by high voltage between power and signal (phone, cable, ...) wires. Plug-in protectors are commonly used on high value equipment with connections to both power and phone or cable, like TVs.

 

Westom pays $290 because he buys from Monster.

 

If not, then the protector was, at best, doing what was done by protection already inside every appliance.

Since westom believes plug-in protectors don't do anything there must be protection inside "every" appliance (nonsense).

 

Normal is to feel a nearby lightning strike while nothing is damaged. Because protection already inside every appliance makes that E-M field irrelevant. For example, lightning struck a building's lightning rod. That maybe 20,000 amps was on a wire to earth and less than four feet from an IBM PC. The PC did not even blink due to protection standard in all electronics even that long ago when internal protection was less robust. Protection inside all appliances is that good.

The NIST guide says:

"Intruder alarm systems using wires between sensors and their central control unit can be disturbed - and damaged in severe cases - by lightning striking close to the house. The wires necessary for this type of installation extend to all points of the house and act as an antenna system that collects energy from the field generated by the lightning strike, and protection should be included in the design of the system, rather than added later by the owner."

 

Near lightning strikes can directly induce voltages with wires acting as "long wire" or "loop" antennas. A loop could be phone wires and power wires. This is a very minor source of damage.

===========================

 

In protecting a device with both power and signal wires (like the DVR or camera) you want to limit the voltage between power and signal wires and the device ground. That is what a plug-in protector does, as explained by the IEEE surge guide starting page 30. That requires all wires, power and signal, to go through the protector.

 

If you are using separate protection devices for the same piece of equipment you run the risk of creating a damaging voltage between power and signal wires that may not otherwise exist. Carefully evaluate the effects of what you are doing.

 

If you are running twisted pair ethernet thorough separate ports on the BNC protector the transmission speed will be impaired. I have never looked but I would think twisted pair ethernet protectors are available. Like a telephone protector, the voltage on all wires to a "ground" connection is limited. Ethernet is trickier because the frequencies are higher.

 

If the DVR has a plug-in protector the BNC protector ground wire could be kludged to the plug-in protector ground (not a great idea but it should work).

 

Ethernet has a relatively high isolation voltage, if the standard is implemented. Only 2 pair are used for 10baseT (don't know which you are using).

[HeadsUp 0]

The Cat5E ethernet cable runs through a BNC balun - see further notes below

 

Near lightning strikes can directly induce voltages with wires acting as "long wire" or "loop" antennas. A loop could be phone wires and power wires.

Yes , inductive effect alone could easily put a zap up a signal cable (of 25 - 100 volts+ _at a guess_) . enough to fry the ass of a sexy DVR card and PC

 

If you are using separate protection devices for the same piece of equipment you run the risk of creating a damaging voltage between power and signal wires that may not otherwise exist. Carefully evaluate the effects of what you are doing.

can you elaborate ?

 

If the DVR has a plug-in protector the BNC protector ground wire could be kludged to the plug-in protector ground (not a great idea but it should work).

I think it better if i run a 4 - 6 sq mm earth cable from the device earth , to a ground stake so i dont create a risk of fire inside my walls from frying the standard earth from the wall outlets

 

Ethernet has a relatively high isolation voltage, if the standard is implemented. Only 2 pair are used for 10baseT (don't know which you are using).

If you are running twisted pair ethernet thorough separate ports on the BNC protector the transmission speed will be impaired. I have never looked but I would think twisted pair ethernet protectors are available. Like a telephone protector, the voltage on all wires to a "ground" connection is limited. Ethernet is trickier because the frequencies are higher.

 

twisted pair ethernet protectors are available , however i am using one pair for video signal which connects to a RJ45-BNC balun then will connect through the protector mentioned . i didnt think a twisted pair protector would like it if i put 24 VAC through the other 3 pairs in the ethernet cable , so i use a separate protector made for low voltage for those other 3 pairs carrying the 24 VAC camera supply .

The other 3 cameras running through the 4 channel protector are all on coax cable and are not fixed to conductive window frame like the other , so i run those direct to the protector

[westom 0]

The Cat5E ethernet cable runs through a BNC balun - see further notes below

bud registered and posts here only because I posted here. He is paid to promote power strip protectors. It is his job. So he follows me everywhere posting nasty and to promote power strip protector myths. It is his job. Where does his post include the always required numbers? No numbers even for his own products? Numbers would expose half truths and subjective claims. Would put profits at risk. Where are the manufacture spec numbers that claim that protection? He has been asked that for most of ten years. And never once posted a manufacturer number that defines protection. He cannot post what does not exist.

 

Now facts with numbers. First, induced surges can create thousands of volts on a nearby 'long wire' antenna. So an NE-2 (a neon glow lamp also found inside illuminated switches) conducts maybe one milliamp of current. Then those thousands of volts drop to tens of volts. Induce surges are that easily made irrelevant. And made irrelevant by protection already inside every appliance.

 

Protection is about protecting from transients that can overwhelm that existing protection. Facilities that can never have damage (ie all munitions dumps) routinely earth 'whole house' protectors. Then induced surges are also made irrelevant.

 

An induced surge is about conducting milliamps. Destructive surges are about thousands of amps that can overwhelm superior protection inside every appliance. Numbers.

 

Second, if a CAT5 cable connects via a balun, then you have protection already found inside every network interface card. Protection routine in ethernet devices is rated about 2000 volts. Protection that is not overwhelmed IF a low impedance (ie 'less than 3 meter) connection to earth is before a transient gets anywhere near that balun. Balun does ineffective protection if earthing is after that balun. (Especially if an appliance is earthed.) A Cat5 protector is earthed at the service entrance so that transients need not seek earth destructively via the balun or via galvanic isolation required on all ethernet devices.

 

BTW, Cat5 protectors are also available for 24 volts since some Ethernet systems also carry 48 volts. Find numbers associated with something called POE.

 

Third, protection is never provided by a protector. If using multiple protection (ie multiple earth grounds), then damage is made easier. So that a transient current does not seek earth via appliances, all incoming wires must connect to the same protection - the same single point earth ground. Otherwise current would be inside hunting destructively for that other earth ground. Damage is always about no surge inside and hunting for earth destructively via appliances. Single point earth ground is critical. Always.

 

Fourth, a plug-in protector has no earth ground. It has a safety ground. A sales promoter will cite an IEEE brochure. Many different protectors are defined. Then it shows protectors that even make damage easier. Page 42 figure 8. A protector, adjacent to a TV and too far from earth ground, simply provides a destructive path through any nearby appliance. In the figure, a protector with only a safety ground (no earth ground) earths that surge 8000 volts destructively through a nearby TV. IEEE even defines that damage with a number: 8000 volts.

 

A point routine from all professionals including the IEEE. Once current is inside a building, then it will hunt for earth destructively. Protection is always about where energy dissipates. Either, destructively inside during a hunt for earth. Or harmlessly outside via a low impedance (ie 'less than 3 meter') connection to earth. Your choice.

 

Dr Martzloff warns about this damage his 1994 IEEE paper when a plug-in (point of connection) protector is used:

Conclusion:

1) Quantitative measurements in the Upside-Down house clearly show objectionable difference in reference voltages. These occur even when or perhaps because, surge protective devices are present at the point of connection of appliances.

 

Fifth, why a constant reference to low impedance (ie 'less than 3 meters')? Impedance says why safety ground is not earth ground.

 

Sixth, you appear to be confused. Never earth the appliance. That only makes an appliance a better and destructive path to earth. Earthing is best distant from protected appliances. Telcos, for example, want something less than 50 meter separation between earthed protectors and electronics. But again, numbers. Separation increases protection. Page 42 figure 8 happens when separation does not exist. 8000 volts destructively to earth via a nearby TV.

 

We engineers, over many decades, have also seen that mistake cause entire network damage. Required were direct lightning strikes without damage. We even learned from some galling mistakes. You need not suffer from those same mistakes. Best solutions here include facts and numbers.

 

Any protection that might work inside the building is already done better inside every appliance. Worry about transients that can overwhelm that internal protection (ie 2000 volts on Ethernet ports). Hundreds of thousands of joules dissipate where? Numbers that always separate profit centers from actual surge protection.

[Soundy 1]

WHO CARES?!

 

Seriously... unless you go absolutely over-the-top with all kinds of grounds and gadgets to protect every inch of every circuit and every device plugged in anywhere in your building (and spend thousands to hire either westom or bud, depending on which one you believe, as a consultant to make sure you didn't miss a trick anywhere), there's always a chance lightning will still find its way in to kill your gear and there's f-all you can do about it.

 

My advice is to stick to the simple, BASIC PRECAUTIONS, and just live with it - by the time you finish implementing everything these guys suggest, you could have just replaced any gear that gets zapped, ten times over, IF it actually ever gets zapped.

 

Yeesh. Get a grip, people.