Lightning eats SSA Excom Minutes

I'm mildly curious as to what pathway lightning might follow through my
carbon and glass fibre glider (not curious enough to experiment
however). Like Micki, I also believe the story.

Ray Warshaw
1LK



Vehicles are quite often struck by lightning and the damage varies from
nothing at all to (most often) damage to electrical and electronic
components, occasionally blown tires and (rarely) broken glass.
Lightning injuries inside vehicles are rare, but have been reported.

Damage to gliders depends on the current magnitude and duration of the
strike. Many gliders have survived weak cloud flashes with little
physical damage - I have personally examined two. The larger currents
of ground flashes can be more exciting as the arcs inside the glider
structure cause a large pressure pulse that can split a wing or blow
off the canopy. A severe positive ground flash blew a glider apart in
Britain a few years ago.

You may get a few warning signs when approaching an electrified cloud.
My Discus 2 produces small sparks from the release handle to my left
leg! Definitely a sign that you should fly somewhere else!

Mike

Mike the Strike wrote:
A severe positive ground flash blew a glider apart in
Britain a few years ago.

That was a K-21. The strike entered at one aileron push rod and traveled
to the other aileron push-rod, where it exited, through the spanwise
alloy push-rods and control linkage.

Ohmic heating in the control linkage produced a strong enough pressure
pulse to cut the fuselage in half and to blow out both canopies. The
skins were blown off both wings as well.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Ray Roberts wrote:
So wasn't it Ben Franklin that invented the fix for this problem, the
lightning rod, connected to earth ground?
I've often wondered why home insurance companies don't insist on having them
installed on each house they insure.
And no, my house doesn't have them either.

Well over 95% of all trees struck by lightning do not leave an
indication. If lightning is rarely so destructive, then why install
lightning rods? Of course, older homes already had a sort of lightning
rod - a cast iron sewer vent pipe. But more often struck are higher
earthing conductors - AC electric wires on telephone poles. If an
earth ground wire on utility poles is intact, then that is often a
better (electrically shorter) path to earth.

Using that paragraph, then one living in a newer home with plastic
pipes and underground utilities wires may consider Franklin lightning
rods (not to be confused with ESE devices).

A more common path to earth through a house is incoming on AC
electric wires (think of those wires as a large antenna network
connected directly to each household appliance). Few who suffer
appliance damage file insurance claims. Either a surge is harmlessly
earthed where utility wires enter a building, or lightning finds a
destructive path to earth via appliances.

Most commonly damaged are appliances that connect to telephone lines
because telco routinely earths a 'whole house' protector for every
subscriber - installed for free. Incoming on AC electric. Through
modem, portable telephone base station, or fax machine. Outgoing to
earth ground via telephone line. Many instead assume this is a surge
that enters via phone line. Fine. But then what was an outgoing path
to earth? No outgoing path means no electricity - no damage. Why did
the transient not take a shorter earthing path via a telco 'installed
for free' protector?

There is no stopping or blocking of lightning as plug-in protector
manufacturers hope you believe. Lightning damage is made irrelevant by
installing a so inexpensive and properly sized 'whole house' protector
on AC mains where that wire enters the building AND earthed to same
electrode used by telephone and cable TV. Effective protectors are
found in Lowes, Home Depot, and electrical supply houses using
responsible brand names such as Intermatic, Siemens, Cutler-Hammer,
Leviton, Square D, and GE. Effective protector for a typically most
destructive lightning path costs about $1 per protected appliance.

That protector also does not stop or absorb anything. A protector is
only as effective as its earth ground. Effective protectors make a
short and temporary connection to earth. Cable TV does not need a
protector since cable is earthed directly by hardwire.

We still build homes as we did when transistors did not exist
pre-1970. Most essential component of a protector system is earth
ground. Best protected homes have lightning protection installed when
footing are pour - halo or Ufer grounding. This because all lightnting
protection (Franklin rods, 'whole house' protector) is only as
effective as the earthing. However even upgrading household earthing
to meet and exceed post 1990 National Electrical Code requirements will
provide massive improvements.

So again, why is this protection not routinely installed? Many
believe a plug-in protector will somehow stop or absorb what 3 miles of
sky could not. Number of claims submitted to insurance companies
remains low. We still don't require effective lightning protection
that has been made essential since 1970. Lightning striking a house
via the roof is rare. Lightning directly striking household appliances
is more common - typically once every seven years. A number that
varies significantly even within neighborhoods. A problem made
irrelevant if each incoming utility wire in each cable is earthed
before it can enter the building. Effective protector earths each
incoming wire so that lightning need not damage household appliance.
How effective is your protection system? Protection begins with
quality of a single point earth ground.

w_tom wrote:
Ray Roberts wrote:
Most commonly damaged are appliances that connect to telephone lines
because telco routinely earths a 'whole house' protector for every
subscriber - installed for free. Incoming on AC electric. Through
modem, portable telephone base station, or fax machine. Outgoing to
earth ground via telephone line. Many instead assume this is a surge
that enters via phone line. Fine. But then what was an outgoing path
to earth? No outgoing path means no electricity - no damage. Why did
the transient not take a shorter earthing path via a telco 'installed
for free' protector?

Current flows in a complete circuit--direction is arbitrary and
irrelevant. What actually happens in many cases of applicance damage is
not voltage surges, it's ground potential difference. If your power,
telephone, cable TV and water services do not enter at the same point
and have common grounding, they can have different "gound" potentials
relative to each other. Even if lightning does not strike your house
directly, it disturbs the ground potential for a large area. This is
why telephones, televisions and refrigerators with ice makers are often
damaged--they are connected to two different systems.

I was working on my computer when my neighbors house got struck - 100 feet
away. The strike went through the roof hiting the upstairs copper water
pipes which set the house on fire. My neighbors were at home watching TV
and reported that a fireball danced around the living room for a few
seconds. Fortunately, all the pinholes blasted into the water pipes put the
fire out within a minute but the total insured damage was still in excess of
$50,000.

My lights dimmed for a second but the computer never blinked. I use a good
UPS.

Bill Daniels


"Doug Haluza" wrote in message
ups.com...

w_tom wrote:
Ray Roberts wrote:
Most commonly damaged are appliances that connect to telephone lines
because telco routinely earths a 'whole house' protector for every
subscriber - installed for free. Incoming on AC electric. Through
modem, portable telephone base station, or fax machine. Outgoing to
earth ground via telephone line. Many instead assume this is a surge
that enters via phone line. Fine. But then what was an outgoing path
to earth? No outgoing path means no electricity - no damage. Why did
the transient not take a shorter earthing path via a telco 'installed
for free' protector?

Current flows in a complete circuit--direction is arbitrary and
irrelevant. What actually happens in many cases of applicance damage is
not voltage surges, it's ground potential difference. If your power,
telephone, cable TV and water services do not enter at the same point
and have common grounding, they can have different "gound" potentials
relative to each other. Even if lightning does not strike your house
directly, it disturbs the ground potential for a large area. This is
why telephones, televisions and refrigerators with ice makers are often
damaged--they are connected to two different systems.

Doug Haluza wrote:

Current flows in a complete circuit--direction is arbitrary and
irrelevant. What actually happens in many cases of applicance damage is
not voltage surges, it's ground potential difference. If your power,
telephone, cable TV and water services do not enter at the same point
and have common grounding, they can have different "gound" potentials
relative to each other. Even if lightning does not strike your house
directly, it disturbs the ground potential for a large area. This is
why telephones, televisions and refrigerators with ice makers are often
damaged--they are connected to two different systems.

If the surge protector has a cable or phone jack connector in addition
to the AC sockets, would that protect the TV or telephone?

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Martin Gregorie wrote:
Mike the Strike wrote:
A severe positive ground flash blew a glider apart in
Britain a few years ago.

That was a K-21. The strike entered at one aileron push rod and traveled
to the other aileron push-rod, where it exited, through the spanwise
alloy push-rods and control linkage.

Ohmic heating in the control linkage produced a strong enough pressure
pulse to cut the fuselage in half and to blow out both canopies. The
skins were blown off both wings as well.

Did the pilots report noticing any sparks, tingling, or other
"electrification" before the strike? I've had lightning strike within a
mile of my glider without noticing any signs of it, before or after.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org

You must mean the ASK21 GBP which was destroyed near the London Gliding
Club, Dunstable on 17th April 1999.

The AAIB report may be found at
http://www.aaib.gov.uk/cms_resources...pdf_500699.pdf .

The pictures and other illustrations do not appear to be available, though I
have them, downloaded when the report was first published.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Mike the Strike" wrote in message
oups.com...


I'm mildly curious as to what pathway lightning might follow through my
carbon and glass fibre glider (not curious enough to experiment
however). Like Micki, I also believe the story.

Ray Warshaw
1LK


Vehicles are quite often struck by lightning and the damage varies from
nothing at all to (most often) damage to electrical and electronic
components, occasionally blown tires and (rarely) broken glass.
Lightning injuries inside vehicles are rare, but have been reported.

Damage to gliders depends on the current magnitude and duration of the
strike. Many gliders have survived weak cloud flashes with little
physical damage - I have personally examined two. The larger currents
of ground flashes can be more exciting as the arcs inside the glider
structure cause a large pressure pulse that can split a wing or blow
off the canopy. A severe positive ground flash blew a glider apart in
Britain a few years ago.

You may get a few warning signs when approaching an electrified cloud.
My Discus 2 produces small sparks from the release handle to my left
leg! Definitely a sign that you should fly somewhere else!

Mike

Eric Greenwell wrote:
Doug Haluza wrote:

Current flows in a complete circuit--direction is arbitrary and
irrelevant. What actually happens in many cases of applicance damage is
not voltage surges, it's ground potential difference. If your power,
telephone, cable TV and water services do not enter at the same point
and have common grounding, they can have different "gound" potentials
relative to each other. Even if lightning does not strike your house
directly, it disturbs the ground potential for a large area. This is
why telephones, televisions and refrigerators with ice makers are often
damaged--they are connected to two different systems.

If the surge protector has a cable or phone jack connector in addition
to the AC sockets, would that protect the TV or telephone?

It is helpful to have a common surge protector for low energy
disturbances, but it cannot completely make up for a lack of proper
bonding in a high energy situation. For example, if the telephone guy
drove a separate ground rod, and it is not bonded to your power service
ground, your $10 surge protector is not going to survive a nearby
strike.

Eric Greenwell wrote:
Doug Haluza wrote:

Current flows in a complete circuit--direction is arbitrary and
irrelevant. What actually happens in many cases of applicance damage is
not voltage surges, it's ground potential difference. If your power,
telephone, cable TV and water services do not enter at the same point
and have common grounding, they can have different "gound" potentials
relative to each other. Even if lightning does not strike your house
directly, it disturbs the ground potential for a large area. This is
why telephones, televisions and refrigerators with ice makers are often
damaged--they are connected to two different systems.

If the surge protector has a cable or phone jack connector in addition
to the AC sockets, would that protect the TV or telephone?

To the extent that the surge protector is able, yes. However, the cheap
power strip surge protectors that people often have are unlikely to absorb
a lighting strike. If this is your goal, make sure you purchase one that
says it can handle it. The good ones have attached equipment guarantees,
where they'll pay for damage if their stuff fails to protect your stuff.

--
Michael Ash
Rogue Amoeba Software