Do you stop using machine during thunderstorm with lightning

TheUglyTruth wrote:

ellen1159 wrote:Dumb question: are we in danger using our machines during a thunderstorm? I always get off the telephone and out of the tub or shower if one is going on, afraid of receiving a shock.

Two questions about world history:

Has anyone every been killed by lightning because they were talking on a telephone?

Has anyone every been killed by lightning because they were in a tub or shower?

I was shocked really good while using a land line when I lived in Texas. The phone line was faulty to begin with. . .I'm still here. . .but boy-oh - wouldn't want to do THAT again.

ellen1159 wrote: I think I should get myself a surge protector for my machinery, not so much for the tiny chance of a lightning strike, but for a general power surge that could fry this expensive piece of plastic.

Unfortunately, many are confusing two completely different devices that, unfortunately, share a common name.

Start by first reviewing what was even introduced in elementary school science.

Lightning (and other typically destructive surges) seek earth ground. A best path to earth was wooden church steeples. Unfortunately the electrical conductor called wood is not a very good conductor. So a maybe 20,000 amps current creates a high voltage. Steeple damaged.

Franklin eliminated damage with a lightning rod. The rod does not do protection. Protection is provided by the connection to and quality of the earth ground electrode. So a maybe 20,000 amps creates a new zero voltage. Nothing damaged.

Lightning (and other typically destructive surges) seek earth ground. A best path to earth is incoming on AC mains to all appliances. Unfortunately appliances are not good conductors. So a maybe 20,000 amps might create a high voltage on any appliance that makes that connection to earth. The surge is incoming to all appliances. But only damaged are ones that make that connection to earth.

For over 100 years, facilities that cannot have damage earthed every incoming wire. Either by a direct (hardwire) connection (ie cable TV, satellite disk). Or by a 'whole house' protector (ie AC electric, telephone). A protector does not do protection. Protection is provided by a connection to and quality of the earth ground electrode. So a maybe 20,000 amps creates a near zero voltage. No appliances damaged.

Lightning rod is for structure protection (as taught in elementary school). 'Whole house' protector is for appliance protection. In all cases, neither a lightning rod nor protector does protection. In both cases, a rod or protector is only a connecting device to what does protection. The art of protection (and what should have almost all your attention) is the earthing electrode. Protection means you know where hundreds of thousands of joules (energy) harmlessly dissipates.

Second, protectors adjacent to appliances have no earthing. Do not discuss it. And therefore do not claim to protect from any the typically destructive surges. Those devices are completely different from a 'whole house' protector (even sold in Lowes and Home Depot to be installed by any informed layman).

Third, other significant numbers and facts apply. This only introduces all to concepts made confusing by hearsay. Completely different devices share a common name. Some also confuse the earthing of a surge with the earthing of appliances.

Concepts demonstrated by Franklin in 1752 were originally taught in school science. And describes what well proven protection from lightning actually does. Routine is to have direct lightning strikes without damage. Your telephone CO (and $multi-million computer) is threatened by about 100 surges with each storm. And no damage. Because telcos routinely earth the superior and many times less expensive solution. Which is completely different from plug-in devices with a same name.

sawinglogz wrote: A clever (though apocryphal) trick that they used to use in radio stations:

Tie a knot your wire.

Any giant surge of current will induce a huge magnetic field, which will in turn (thanks to the knot) "resist" the current (inductive reactance, technically). All that energy has to go somewhere, of course, so it basically vaporizes the wire at the knot.

That's nonsense. It might actually blow up the knot, but it's not going to protect the equipment.

There are two different questions here.

1) Risk to the human. Let's call that electrocution.
2) Risk to damage the machine.

Risk of electrocution

As long as you don't have a heated hose, there's probably a slight increase in electrocution risk from using the CPAP during a thunderstorm, but I wouldn't give it a second thought. You're fairly well insulated and most of the current is likely to take another path than through the CPAP machine, through the non-conductive hose, through you, through your non conductive bed, etc.

With a heated hose, there's a little higher risk because you're more intimately connected to the machine, but even then, there's not a real good connection to you, and probably not that much of a risk.

Sometimes, lightning does what it darn well wants to and ignores ground rods, conductors, etc. and hits what it wants to. Lighting might just go through the window and hit you directly. Precautions like surge protectors and grounding just improve the odds.

Surge protection is there mostly to take care of nearby lighting strikes, and strikes to the power lines some distance away. It's not meant to stop a direct hit. Even the best home style surge protection isn't going to do much against a direct strike that follows a path through the wiring with enough energy to electrocute you.


Risk of damage to the machine:

Even with good surge protection, there's some risk to the equipment. The better the surge protection, the lower the chance of damage to the equipment. Surge protection is good. Whole house is better. Turning off a switched outlet strip is a step better. Unplugging the power cord is another step up. Also unplugging the cord from the back of the machine is even better.

I don't bother turning off the CPAP unless lighting is really frequent and close enough that I'm not sleeping anyway, but I don't have a heated hose. If it's going to be a bad lightning day, and I'm not at home, I'll turn off the power strip before leaving.

I use individual surge protectors and a surge strip. I don't have a lot of faith in them, but they improve the odds a bit and are cheap. Whatever surge protector you use, be sure to check the little light on the protector to be sure it's still working. In many surge protectors, the protecting element can burn out and you will no longer have any protection. Be sure to read the instructions and check the light frequently.

Surge protectors (any kind)are useless if the lightening hits the ground next to the house and the surge goes UP the grounding equipment. I have seen the melted computers.

Surge protectors are to lightening as little 2 foot plastic fences trying to stopping a herd of stampeding cows.

BlackSpinner wrote:Surge protectors (any kind)are useless if the lightening hits the ground next to the house and the surge goes UP the grounding equipment. I have seen the melted computers.

Unfortunately, too many make conclusions only from observation. Defines is damage from a ground strike because the building's earth ground was defective. For over 100 years, such strikes resulted in no damage. An example demonstrates the concept.

Lightning is a connection from the cloud to earthborne charges maybe 5 kilometers distant. A shortest path is maybe 3 kilometers to a tree. And four kilometers via earth to those charges. Standing maybe 10 meters from that tree was a cow. What kills the cow? That path from cloud and through a tree is also up the cow's hind legs and down its fore legs. Cow killed due to no single point earth ground. Same well proven concept also explains "melted computers".

Damage is always about a current incoming on one conductor. And outgoing on some other. Protection is always about connecting that current to earth on a path that remains outside the building. If the building does not have a single point earth ground, then household appliances can be damaged by the same concept that also killed the cow.

What Westom says has some truth, it's something w e weren't taught in school. I worked around machines that ran on 7200 volts of a/c, at safety training they brought in a large fish tank filled with water and ran a demostration of electricity.

They had a volunteer place his hands in the water clasp together. They took room a/c hooked thru a variable reostat transformer with two wires in the water. As they turn it on and cranked up the output voltage you could feel it, but it was bearable. Then he would have you separate your hands and move them apart. As you did it knocked you across the room, not pleasant. They never taught us that in school.

The point of this training was we were operating heavy equiptment and had that type if power around. If you had a power line fall on your equiptment your vehicle acted as a cage so the electricity wouldn't bother you as you are charged to the same level. The problem comes when you climb off the machine.

Where the charge goes into the ground it energizes the ground, at different lengths from the entry point the current changes, so if you have to jump off the equiptment you must land with your feet together (one contact point) to keep from being fried. Then hop out of the area, hard to do! Best bet to stay on the machine until the power is cut off. Sometimes the machine catches fire and you have to test your luck. Big electricity, has rules, but doesn't always do as we think. Jim

BlackSpinner wrote:Surge protectors (any kind)are useless if the lightening hits the ground next to the house and the surge goes UP the grounding equipment. I have seen the melted computers.

Surge protectors are to lightening as little 2 foot plastic fences trying to stopping a herd of stampeding cows.

In one station that I worked at the towers were directly in the field that was part of our campus. Lightning blew up our transmitter - and - some of the support equipment.

Spark gaps at the towers - Plus surge protection in the transmitter - Plus surge protection in the power to the support devices - worked. All proved themselves necessary.

Surge protectors do not care where the difference in potential comes from or which way the current wants to flow. Each one has limits, however, in how much protection it can offer.

While the surge devices available in the stores will not deal with a direct strike or the currents close to that strike they will protect the equipment further away from damage and are an essential part of any well designed protection scheme. The more the merrier.

Take care.

Todzo

archangle wrote:

sawinglogz wrote: A clever (though apocryphal) trick that they used to use in radio stations:

Tie a knot your wire.

Any giant surge of current will induce a huge magnetic field, which will in turn (thanks to the knot) "resist" the current (inductive reactance, technically). All that energy has to go somewhere, of course, so it basically vaporizes the wire at the knot.

That's nonsense. It might actually blow up the knot, but it's not going to protect the equipment.

The energy of lightning is in the 1-3 megahertz range. Not really high frequency but high enough that a loop in the wire creates enough inductance that the current is more likely to seek another path.

Since no energy is absorbed by inductance, indeed, since is reduces the current that would flow in the wire it protects the wire as well as the downstream equipment.

Putting a loop in a wire will tend to limit the lightning current that can flow in that wire. I think of it as a way to protect the downstream surge protectors from currents which are too high for them. Any bend will help. A loop is a much much better choice than a knot.

Todzo wrote: Putting a loop in a wire will tend to limit the lightning current that can flow in that wire.

True if the surge is from a voltage source. Surges are a current source. That means voltage will increase as necessary to blow through anything that might stop it.

Impedance (ie a longer wire) is why protectors work better when distant from electronics. However that impedance is virtually useless if current does not have a better and alternative path. That's why facilities that cannot have damage (while suffering even 100 surges with each storm) locate the protection virtually on earth ground. And up to 50 meters distant from electronics. The protector is the better and alternative path to earth.

To be effective, a knot that stops a surge also means that same antenna wire obstructs high frequency radio and TV signals. If a knot does not obstruct those signals, then it obviously is woefully insufficient to stop a surge.

westom wrote:

Todzo wrote: Putting a loop in a wire will tend to limit the lightning current that can flow in that wire.

True if the surge is from a voltage source. Surges are a current source. That means voltage will increase as necessary to blow through anything that might stop it.

Impedance (ie a longer wire) is why protectors work better when distant from electronics. However that impedance is virtually useless if current does not have a better and alternative path. That's why facilities that cannot have damage (while suffering even 100 surges with each storm) locate the protection virtually on earth ground. And up to 50 meters distant from electronics. The protector is the better and alternative path to earth.

To be effective, a knot that stops a surge also means that same antenna wire obstructs high frequency radio and TV signals. If a knot does not obstruct those signals, then it obviously is woefully insufficient to stop a surge.

Remember that voltages and currents are alternating at between 1 and 3 million times a second. Not 60 Hz AC but 2,000,000 Hz AC.

The impedance of a wire happens as the magnetic currents in that wire cut through the wire as they expand or contract about the wire - which happens about two million times a second where lightning is concerned. When you form a wire into a loop the magnetic force cuts into not only the parts of the original wire but also the entire wires in close proximity profoundly increasing the impedance (inductance - resistance to the current flow at the high frequency). Since there are other places for the currents to go outside the wire it is unlikely that the voltage in the wire will become great enough to blow through the insulation and air - as well the voltage is distributed across the wire and loops.

Surge protectors work by limiting the voltage rise across a point (say one of the AC plug tines and ground). Any currents that would raise the voltage beyond a certain point are shunted (re-directed) directly to the ground pin. When that current does flow heat is created in the surge device - which - can only take so much. If the impedance in the line limits the current through the surge protector the device has a better chance.

Todzo wrote: If the impedance in the line limits the current through the surge protector the device has a better chance.

You are assuming protection of a protector is relevant. That is true for many grossly undersized protectors recommended to and purchased by consumers. When installing effective protection (ie earthing a 'whole house' protector), we want the lowest impedance for a surge (maximum current) through that protector to earth. Good protectors need no such protection.

When it comes to protection, wire (as short as possible, no sharp bends, no splices, etc) is a best protector. Because it creates lowest impedance and voltage. Protectors are used only when superior protection (a wire) cannot be implemented. But again, voltage is only a symptom of undesirable impedance or other undesirable obstructions. Protection is always about a current that cannot be stopped. That will blow through anything that tries to stop it (ie a knot). That current is why a 'whole house' protector is at least 50,000 amps.

Many discuss surge protection in terms of a voltage. Protection is always about a current source. A concept rarely understood by consumers and so many who recommend plug-in protectors. Nobody need to learn such details. But discussing such details defines the fewer who understand surge protection. Why a protector must be both distant from electronics and within feet of earth ground. And also why knots are virtually near zero protection.

If frequency was less than one million cycles, a knot would be almost non-existent. A knot is only one step above near zero for typical surges. Since a surge is a current source, it must have a low impedance connection to earth. Voltage is only a symptom of excessive impedance.

westom wrote:You are assuming protection of a protector is relevant. .

If you are protecting a specific device (e.g. CPAP machine) it most certainly is. The theory is good and my over 20 years of experience doing this tells me that it most certainly works also.

If the currents are shunted around the devices the path to ground becomes irrelevant. Your approach is most likely to explode the very protection device you are installing! I think you should think about that.

I started disconnecting from the machine during lightning storms one storm late.

Todzo wrote: If the currents are shunted around the devices the path to ground becomes irrelevant. Your approach is most likely to explode the very protection device you are installing!

Please read, instead, what was posted. Either a wire or protector shunts BEFORE that current can enter a building (and away from electronics or appliances). Or it does virtually nothing useful. Obviously, an effective protector, with no protecting impedance, means that protector does not fail or explode. A failed protector means it was grossly undersized and ineffective.

Why is a minimally sufficient 'whole house' protector at least 50,000 amps? Because a direct lightning current passes through that protector without causing damage. Obviously the well proven solution means no protector fails or 'explodes'.

OP asked about protecting his CPAP. His 'whole house' protector details do not define that installation. Quality of and 'low impedance' connection to single point ground determines CPAP protection. How well earthed is his 'whole house' protector? Answering that question defines CPAP and all other appliance protection. Even disconnecting is insufficient and unreliable protection.

BTW, a grossly undersized protector that needs protection using impedance is also a potential house fire.