Lightning eats SSA Excom Minutes

On Nov 23, 9:56 am, "w_tom" wrote:

There is no stopping or blocking of lightning as plug-in protector
manufacturers hope you believe.
The best information I have seen on surges and surge protection is at
http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf
- the title is "How to protect your house and its contents from
lightning: IEEE guide for surge protection of equipment connected to AC
power and communication circuits" published by the IEEE in 2005 (the
IEEE is the dominant organization of electrical and electronic
engineers in the US).

A second guide is
http://www.nist.gov/public_affairs/p.../surgesfnl.pdf
- this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the National
Institute of Standards and Technology (the US government agency
formerly called the National Bureau of Standards) in 2001

Both guides were intended for wide distribution to the general public
to explain surges and how to protect against them. The IEEE guide was
targeted at people who have some (not much) technical background.

Both say plug-in surge suppressors are effective.

All interconnected devices, like a computer and printer, need to
connect to the same surge protector. If a device, like a computer, has
external connections like phone or LAN, all those wires have to run
through the surge suppressor for protection. This type of suppressor is
called a surge reference equalizer (SRE) by the IEEE (also described by
the NIST). The voltage on all wires connected to the SRE (power, phone,
CATV, LAN, ...) are clamped to a common ground at the SRE and the
voltages are held to a value that is safe to the connected device.
Ratings vary from junk to very high.

While a single point ground with phone, CATV, ... protectors connecting
with short wires to the grounding electrode wire at the power service
is best for eliminating the ground potential differences in Doug's
post, SREs also provide protection.


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.
As is clearly described in the IEEE guide, plug-in suppressors work by
clamping,.They do not work primarily by earthing, or stopping,
blocking, absorbing.


Many
believe a plug-in protector will somehow stop or absorb what 3 miles of
sky could not.
Among those who believe that are the IEEE and NIST.

--
bud--

bud-- wrote:
On Nov 23, 9:56 am, "w_tom" wrote:

There is no stopping or blocking of lightning as plug-in protector
manufacturers hope you believe.
The best information I have seen on surges and surge protection is at
http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf
- the title is "How to protect your house and its contents from
lightning: IEEE guide for surge protection of equipment connected to AC
power and communication circuits" published by the IEEE in 2005 (the
IEEE is the dominant organization of electrical and electronic
engineers in the US).

A second guide is
http://www.nist.gov/public_affairs/p.../surgesfnl.pdf
- this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the National
Institute of Standards and Technology (the US government agency
formerly called the National Bureau of Standards) in 2001

Both guides were intended for wide distribution to the general public
to explain surges and how to protect against them. The IEEE guide was
targeted at people who have some (not much) technical background.

Both say plug-in surge suppressors are effective.

All interconnected devices, like a computer and printer, need to
connect to the same surge protector. If a device, like a computer, has
external connections like phone or LAN, all those wires have to run
through the surge suppressor for protection. This type of suppressor is
called a surge reference equalizer (SRE) by the IEEE (also described by
the NIST). The voltage on all wires connected to the SRE (power, phone,
CATV, LAN, ...) are clamped to a common ground at the SRE and the
voltages are held to a value that is safe to the connected device.
Ratings vary from junk to very high.

While a single point ground with phone, CATV, ... protectors connecting
with short wires to the grounding electrode wire at the power service
is best for eliminating the ground potential differences in Doug's
post, SREs also provide protection.


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.
As is clearly described in the IEEE guide, plug-in suppressors work by
clamping,.They do not work primarily by earthing, or stopping,
blocking, absorbing.


Many
believe a plug-in protector will somehow stop or absorb what 3 miles of
sky could not.
Among those who believe that are the IEEE and NIST.

I suggest that you go back and re-read your references. For instance,
on pg. 38:

Well-designed and well-built plug-in protectors will actually withstand
the
10,000 A (8x20 µs) surge current, and that is rating required by NFPA
780-2004
for plug-in protectors. However, the UL 1449 Standard only requires
plug-in
protectors to withstand, without damage, ~20 500 A surges. Inexpensive
protectors using the 6C type of circuit are designed to respond to
overload by
opening the protective fusing shown in Figure 6C, sometimes at surge
currents
barely over the 500 A limit. Because the UL 500 A surge withstand
requirements
are relatively weak, it is important to have both a hard-wired
protector at the
service entrance and a plug-in protector at the critical loads.

This clearly recommends that you don't depend upon a surge protector
alone, simply because the minimum UL requirements are REALLY a minimum.
Most people don't know that surge protectors use devices (MOVs) that
have a limited life, and they don't have a visible indicator showing
how much of their life is left. High quality surge protectors are sold
by www.zerosurge.com.

The IEEE report confirms what w_tom was saying about voltage
differentials on the building grounding during a lightning strike:

If wiring comes into a building at many different points, it is much
more difficult
to get proper protection against lightning surges. Even if surge
protectors are
installed at these alternate entry points, the long ground wires
running back to the
main building ground greatly reduce the effectiveness of the
protectors. In highlightning
areas, where lightning protection is a major concern, it is worth
routing
as many AC and signal cables as possible past the building power entry
point, to
facilitate good grounding for protectors and cable sheaths

I highly recommend a thorough reading of the IEEE document for a
complete discussion of this issue. The take home message: individual
surge protection devices ARE NOT a complete lightning protection plan.

Tom Seim
Richland, WA

Mike the Strike wrote:
From the latest SSA news:

"While I know this is going to sound like an excuse right up there with
"The dog ate my homework assignment..." last week the Carswell house in
Midlothian TX was struck by lightning (really).


Well, here in Tucson, we are sometimes known as the "lightning capital"
of America...and I have to tell you, we have a tree in the front yard
that was struck last year, while we were sitting in the house...sounded
like a terrorist bomb attack. The house shook, the power wavered off
and on, and the dogs went to hide. I firmly believe the story!

I have yet (lo, these many years) ever been able to recover a hard
drive from any power surge that great....sorry, I don't hold much hope!
Good luck.

micki minner

My mobile medical unit was struck by lightning while traveling on the
interstate near Junction, TX some years ago. The bolt struck the left
forward corner of the trailer and traveled forward to the tractor
wiping out the lights, engine computer, gauges, head, taillight and
marker bulbs and much of the wiring and rearward through the trailer
where the only damage was to the ceramic insulators in the x-ray
processor heater located at least 25 feet aft of the strike. The
trailer framing is steel so the charge apparently traveled through it
to the road protecting the x-ray equipment; the entire cab on the
tractor (GMC Astro), however is fibreglass and the wiring, gauges,
engine, frame rails and computer were the pathway. The driver was
badly frightened, but otherwise OK.

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


MickiMinner wrote:
Mike the Strike wrote:
From the latest SSA news:

"While I know this is going to sound like an excuse right up there with
"The dog ate my homework assignment..." last week the Carswell house in
Midlothian TX was struck by lightning (really).


Well, here in Tucson, we are sometimes known as the "lightning capital"
of America...and I have to tell you, we have a tree in the front yard
that was struck last year, while we were sitting in the house...sounded
like a terrorist bomb attack. The house shook, the power wavered off
and on, and the dogs went to hide. I firmly believe the story!

I have yet (lo, these many years) ever been able to recover a hard
drive from any power surge that great....sorry, I don't hold much hope!
Good luck.

micki minner

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 |

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

Sounds like the bonding strap may be broken on your pedals, or possibly
it was not replaced properly when the tow hook was serviced. Although
fixing this may make your early warning less effective, you will be
better off in the long run.

Mike the Strike wrote:

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!

MickiMinner wrote:
Mike the Strike wrote:
From the latest SSA news:

"While I know this is going to sound like an excuse right up there with
"The dog ate my homework assignment..." last week the Carswell house in
Midlothian TX was struck by lightning (really).


Well, here in Tucson, we are sometimes known as the "lightning capital"
of America...and I have to tell you, we have a tree in the front yard
that was struck last year, while we were sitting in the house...sounded
like a terrorist bomb attack. The house shook, the power wavered off
and on, and the dogs went to hide. I firmly believe the story!

I have yet (lo, these many years) ever been able to recover a hard
drive from any power surge that great....sorry, I don't hold much hope!
Good luck.

micki minner
http://www.lightningsafety.noaa.gov/images/map.pdf shows the propensity
for lightning.

Florida has the most casualties, mostly on golf courses, but trails
behind many states in intensity.

The most intense storms I've personally experienced were in Nebraska
and Turkey.

Colorado has a lot of tornadoes, but tipping a shed or cow makes little
news.

Frank Whiteley