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handlebar

join:2011-02-25
Grover, NC

lightning protection

Roadrunner was installed this afternoon. I liked the fact that a one-foot wire connects the service entrance to my power-company grounding electrode.

The installer said there was no need to run the cable through a surge protector at my computer. Is it wise not to have a surge protector on the cable?


CptGemini
Inside your computer
Premium
join:2004-11-29
Corpus Christi, TX
kudos:6
I would put one anyway. It won't hurt to have the extra protection.


ChillyCat6

join:2004-09-07
Chesterland, OH
kudos:1
reply to handlebar
MYTH: A surge protector or UPS device will provide sufficient protection against all lightning strikes, including a direct lightning strike.

TRUTH: Unfortunately not. A common surge protector will stop voltage spikes and surges, but not the violent, catastrophic burst of current from a close lightning strike. Direct lightning current is simply too big to protect with a little electronic device inside a power strip, or even a hefty UPS unit. If your UPS or surge protector is in the way of the lightning's path, all or part of the lightning will just flash over or through the device - regardless of the amount of capacitors and battery banks involved.

Even 'disconnects', or devices that physically switch off power to a device by activating a set of contacts, will not guarantee protection. A small air gap will not stop a lightning bolt that has already jumped across miles of air. It won't think twice about jumping a few more inches, or even a few more feet, especially if the 'path of least resistance' to ground is across the contacts of the disconnect switch.

Not only that, but not even a full-fledged lightning protection system with rods, cables and grounds will guarantee against damage to electronics and computers. For any system to provide 100% protection, it must divert almost 100% of the lightning current from a direct strike, which is nearly physically impossible: Ohm's Law states that for a set of resistances connected in parallel, the current will be distributed across ALL resistances, at levels inversely proportional to the different values of resistance. A house or building is nothing more than a set of resistors 'connected' in parallel- the electrical wiring, plumbing, phone lines, steel framework, etc. (Even though plumbing and electrical wiring, for instance, may not be physically connected, lightning will use side flashes across air gaps to effectively connect them). In a direct lightning strike, the current will not follow only one path- it will distribute itself across all paths to ground depending on each path's resistance.

Lightning current often peaks at 100,000 or more Amperes. With that in mind, consider if you have a lightning protection system installed, and your house is hit directly by lightning. If the protection system takes even 99.9% of the current, then your electrical wiring may take the remaining 0.1%. 0.1% of 100,000 Amperes is a 100 Amp surge through your lines- which may be enough to take out your computer.

It is not uncommon for 'side flashes' to occur inside a house or building, where all or a part of the lightning will jump across an entire room to reach ground- such as from the electrical wiring system to well-grounded water pipes. If your computer is in the way, it'll be time to shop for a new one, even if you have the most expensive protection system installed.

A 'side flash' often occurs when lightning branches out into several channels as it tries to bury itself deep into earth. So even if the bulk of the current is flowing to ground through the heavy cables of your protection system, there can be small 'overflow' disharges, even if the lightning hits outside of the structure. Such an event was experienced by my Grandmother, who witnessed a 6-foot long blue spark jump across the room from a wall outlet to the kitchen faucet as lightning struck nearby.

Guarantees on the packaging of UPS/surge protection devices are somewhat misleading when it comes to lightning protection, implying that the devices can stop any effects of a strike. In some cases, they will - as long as they aren't in or near the direct line of fire. But in reality, nothing can guarantee absolute protection from a direct or very close strike.

All this doesn't mean that you shouldn't use a surge protector, UPS, disconnect, or a full-fledged lightning rod system. Any device will provide some degree of protection from everyday power line spikes and distant lightning strikes. But when lightning hits nearby or directly, all bets are off.

The best, and cheapest, way to protect your stereo, television, computer, or any electronic appliance is to unplug all power, telephone (modem), and antenna connections during a thunderstorm.

westom

join:2009-03-15
kudos:1

2 edits
reply to handlebar
said by handlebar:

The installer said there was no need to run the cable through a surge protector at my computer. Is it wise not to have a surge protector on the cable?

A protector too close to electronics and too far from earth ground sometimes earths a surge destructively through electronics. Why would you want one?

No protector does protection. If a cable is properly earthed, then cable already has the best protection. But only if your earthing both meets and exceeds post 1990 code. They can only connect to protection that you have provided. How good is your earthing?

That eliminates surges incoming on cable. Surges do damage by entering an appliance via one wire. While the same current is also outgoing on another. The most common source of surges is AC electric. Once that energy is inside a building, nothing will stop it from finding earth destructively via some appliance.

A good connection to earth? Incoming on AC mains. Outgoing to earth via the cable. Whatever is between AC mains and that cable is at risk.

Worry about other wires that deposit a surge inside your building. Once inside, nothing can avert a destructive hunt for earth. Nothing. Either you also earth all AC electric wires at service entrance using a 'whole house' protector. Or ports connected to the cable might be damaged by a surge from AC mains seeking the cable ground.

Protection is always about no energy inside. Your cable has already done its part if earthed before entering. But if you do not do same for AC electric, then your still have no effective protection.

Cable guy is right. A protector on their cable does nothing; does not even claim to do anything useful. Others educated by advertising will disagree. But 100 years of engineering experience says the cable guy is right.

Protectors adjacent to electronics do not add protection. Do not even claim to do that protection - as manufacturer specs so glaringly admit. Protectors too close to appliances and too far from earth ground sometimes make damage easier. Effective protectors always have that short (ie 'less than 10 foot') wire that connects to earth. You need that 'whole house' protectors on AC mains.


handlebar

join:2011-02-25
Grover, NC
reply to ChillyCat6
said by ChillyCat6:

Not only that, but not even a full-fledged lightning protection system with rods, cables and grounds will guarantee against damage to electronics and computers. For any system to provide 100% protection, it must divert almost 100% of the lightning current from a direct strike, which is nearly physically impossible: Ohm's Law states that for a set of resistances connected in parallel, the current will be distributed across ALL resistances, at levels inversely proportional to the different values of resistance.

Lightning current often peaks at 100,000 or more Amperes. With that in mind, consider if you have a lightning protection system installed, and your house is hit directly by lightning. If the protection system takes even 99.9% of the current, then your electrical wiring may take the remaining 0.1%. 0.1% of 100,000 Amperes is a 100 Amp surge through your lines- which may be enough to take out your computer.

It is not uncommon for 'side flashes' to occur inside a house or building, where all or a part of the lightning will jump across an entire room to reach ground- such as from the electrical wiring system to well-grounded water pipes.

All this doesn't mean that you shouldn't use a surge protector, UPS, disconnect, or a full-fledged lightning rod system. Any device will provide some degree of protection from everyday power line spikes and distant lightning strikes. But when lightning hits nearby or directly, all bets are off.

The best, and cheapest, way to protect your stereo, television, computer, or any electronic appliance is to unplug all power, telephone (modem), and antenna connections during a thunderstorm.

I believe it's usually the ground surge that wipes out cattle and computers. Contrary to the electrical code, Bellsouth often put their service entrance 30 feet from the power entrance and didn't bond the grounds.

When I saw the situation I bonded my electrodes. In 1998, lightning hit a tree 30 feet from my electrical service entrance. I was online at the time. It knocked out my phone service, but the bonding and surge protector prevented damage to my computer equipment. About 2002, lightning lit the neighborhood orange when it struck a tree 60 feet from my service entrance. It blew bark 40 feet. I was online. No electrical damage.

In 2005, I was online when my house got hit. Masonry from both chimneys was blown a long away. Lightning blew a hole in the roof and knocked off siding. It wrecked perhaps $2000 worth of electronics, including a stereo receiver that wasn't hooked up or plugged in. My CRT was left with colors all over from the intense electrical field. However, none of my computer stuff was damaged. There's a case where equipment plugged into a surge protector fared better than a disconnected receiver.

I was online in 2010 when my house got hit again. I may have had $1000 worth of electronics wrecked, but none of my computer stuff. Both times my house got hit, there had been no lightning or thunder within 30 miles. It wasn't stormy and the sky wasn't ominously dark. There was no warning for me to unplug things.

A thousand miles from here, I was running through the living room in a thunderstorm when lightning jumped from the ceiling light to the floor, in arm's reach in front of me. Upstairs, my sister screamed. Lightning had come from the ceiling and hit the brass bed she was in.

Decades later, she moved into a farmhouse. Popping and blown bulbs were routine in thunderstorms. I solved it by bonding.

I'm glad the cable is bonded to the power ground at the service entrance, but in a storm there could be instants when, at the modem end, the cable could be thousands of volts different from the power circuitry at that point. It seems to me that a surge protector could absorb that energy. It might be thousands of amps, but it should be brief, not thousands of joules.

TWCdude

join:2006-04-28
San Antonio, TX
kudos:23
reply to handlebar
Lightning storms are pretty bad no matter what. I get many calls after each major storm with dead cable boxes and modems and it will kill other devices attached to them as well. Dead pc nics are common with dead modems

westom

join:2009-03-15
kudos:1

2 edits
reply to handlebar
said by handlebar:

It seems to me that a surge protector could absorb that energy. It might be thousands of amps, but it should be brief, not thousands of joules.

No surge protector absorbs that energy. View its numbers. Protectors are hundreds of joules. Destructive surges are hundreds of thousands of joules. No protector works by blocking or absorbing surges. Protectors are only connecting devices. Either a protector connects hundreds of thousands of joules harmlessly to your single point earth ground (ie phone line and AC electric ground now bonded into one big earth ground). Or that protector does nothing useful.

You have assumes a surge automatically destroys everything. It does not. A surge inside the building goes hunting. It selectively destroys appliances that make a better connection to earth. Protection is always about connecting every single wire inside every incoming cable to the same earth ground. So that surge energy is not even inside a building. That is why earthing is so critical.

One AC electric wire connects directly. Other two must be connected via a 'whole house' protector. Telephone already has a 'whole house' protector installed for free. But yours was ineffective when not connected to a 'single point ground'. Uniting both into one big ground created single point ground.

No protector does protection. Protection is always defined by the quality of earthing. Where all energy is harmlessly absorbed. Some wires (ie cable) need no protector - connect directly to earth. But in every case, either the protector makes that low impedance (ie 'less than 10 foot') connection to earth. Or that protector is ineffective. Bonding short to earth is critical.

Appliances already contain protection equal to or better than anything that might be on its power cord. The computer had some protection with or without an adjacent protector. Which appliances connect surge current better to earth? Those are the damaged appliances. Protection inside other appliances (ie GFCI, dimmer switch, digital clock) was probably more than sufficient because they were not the better connection to earth.

Bonding is important. But bonding must connect to every incoming wire. Either directly or via a 'whole house' protector.

Same applies to lighting rods. Many will argue point verse blunt. They miss the point. What is true for protectors is also true for lightning rods. Only as effective as what does the actual protection - earth ground. You may also want to upgrade earthing for those rods.

handlebar

join:2011-02-25
Grover, NC
reply to TWCdude
said by TWCdude:

Lightning storms are pretty bad no matter what. I get many calls after each major storm with dead cable boxes and modems and it will kill other devices attached to them as well. Dead pc nics are common with dead modems

With DSL, I liked to unplug the phone line when a thunderstorm approached. The TW installer must have screwed the cable on with a wrench. With or without a protector, would it be wise to disconnect the cable if a storm threatened or I was leaving the house? Do they make slide-on adapters?


DrDrew
That others may surf
Premium
join:2009-01-28
SoCal
kudos:20
reply to CptGemini
Between possible ground loops and frequent limitations in the frequencies passed most common surge protectors I wouldn't recommend it


rcdailey
Dragoonfly
Premium
join:2005-03-29
Rialto, CA
reply to handlebar
Why not just unplug the ethernet cable, which should be the only connection between your PC (or your router) and the cable modem?
--
Don't let the pluperfect be the enemy of the perfect.

westom

join:2009-03-15
kudos:1
reply to handlebar
said by handlebar:

With DSL, I liked to unplug the phone line when a thunderstorm approached. The TW installer must have screwed the cable on with a wrench. With or without a protector, would it be wise to disconnect the cable if a storm threatened or I was leaving the house?

Bell South disconnects their CO computers with every approaching thunderstorm. Phone service disappaears with each storm.

Of course not. Why does your town have phone service four days after each storm? Why do they not have electronics damage? Because their wires are also properly earthed before entering a building.

If you must disconnect, then never use the DSL. Destructive surges occur mostly without warning. Meanwnhile, a most common source of DSL damage is incoming on AC mains. Finding earth ground destructively via the DSL line. Because DSL lines also have superior and earthed protectors installed for free.

Bell South suffers about 100 surges with each thunderstorm. And no damage. The average home suffers about one every seven years. You are advised to do what has been done for over 100 years because it works even with 100 surges per storm. Confirm the earth ground (that you are responsible for) is properly connected the 'installed for free' DSL protector.

Cable has even better protection if properly connected to single point ground. If any wire (ie satellite dish) enters without that earthing, then every household appliance is at risk. Also disconnect the diswasher, refrigerator, and all smoke detectors.

Or do what the informed have been doing for over 100 years. That means properly earthing a 'whole house' protector on AC mains. The most common source of DSL and cable appliance damage is AC mains. Disconnecting is a least reliable solution.