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Section 5.4.3:
WORLD
WIDE OPPOSITION TO ESE LIGHTNING RODS.
copyright (c.) 1999 by Abdul M. Mousa,
All Rights Reserved in All Media
I wish
to make readers aware of the extent of the opposition of the scientific
community to Early Streamer Emission (ESE) lightning rods. In an unprecedented
move, 17 scientists who are members of the Scientific Committee of ICLP
(International Conference on Lightning Protection) issued a joint statement
opposing ESE lightning rod technology. The scientists represent 15 countries
including the USA, Japan, Great Britain and 12 countries from Continental
Europe, and 14 of them are well-known university professors.
The statement
was sent to NFPA (National Fire Protection Association of the USA) in
connection with the NFPA review regarding whether a standard for ESE devices
should be considered. It is worth noting that a draft standard for such
devices was rejected by the NFPA in 1995.
ESE proponents,
led by the Heary Brothers, then sued the NFPA alleging improper motive
behind the rejection of their draft standard. The litigation was settled
out of court by the NFPA agreeing to form a new panel to re-consider whether
ESE devices have a scientific basis. The ICLP statement was submitted
to the NFPA Panel, which is headed by Dr. John L. Bryan, in connection
with the subject review. A list of the 17 scientists follows:
1. Professor Ch.
Bouquegneau (Belgium)
2. Mr. L. Dellera (Italy)
3. Professor O. Farish (United Kingdom)
4. Professor Z. Flisowski (Poland) - Vice-President of ICLP
5. Professor W. Hadrian (Austria)
6. Professor T. Horvath (Hungary)
7. Dr. J.
Huse (Norway)
8. Professor T. Kawamura (Japan)
9. Professor C. Mazzetti (Italy) - President of ICLP
10. Professor C. Menemenlis (Greece)
11. Mr. E. Montandon (Switzerland)
12. Professor Aa. E. Pedersen (Denmark) - Honorary Member
13. Professor S. Lundquist (Sweden) - Honorary Member
14. Professor V. Scuka (Sweden) > 15. Professor M.A. Uman (USA)
16. Professor P.C.T. van der Laan (Netherlands) > 17. Professor J. Wiesinger
(Germany)
A transcript
of the ICLP fax to NFPA, which was dated February 26, 1999, follows:
THE
ICLP STATEMENT TO THE NFPA DRAFT STANDARD 781.
Referring
to the NFPA request for information and comments to their Panel set up
to prepare a reexamination report of the NFPA draft standard 781 on ESE
devices, which has been reopened for a new evaluation, ICLP (International
Conference on Lightning and Lightning Protection) wishes to give the following
information.
THE
ASSUMPTIONS BEHIND THE NFPA ESE DRAFT STANDARD 781
Lightning
protection is a primary safety issue. Protection systems and means are
provided in order to ensure personal safety and to reduce the risk of
fire, equipment and systems damages, malfunctions and production interruptions
etc. to a tolerable level. To fulfill these requirements and avoid legal
actions, including claims of economical losses etc., standard of lightning
protection systems should be based on scientifically proven and indisputable
technical arguments.
The claimed
function of an ESE device is the triggering of an early upwards streamer/leader
at a time, delta T, earlier than the triggering time of a simple lightning
rod. The time difference, delta T, is defined as the time advantage. It
is proposed that this time advantage be multiplied by a constant velocity
of the upwards progressing discharge. The velocity multiplied by delta
T determines the length, delta L, of the triggered discharge.
The philosophy
of the promoters of ESE rods is, that an ESE rod of the length L gives
the same protection as a simple lightning rod of length, L, plus the above-mentioned
delta L, i.e., L + delta L.
On this
assumption the protection, as specified in the draft standard, is designed
in principle using the Rolling Sphere Method.
ICLP's
COMMENTS AND STATEMENTS
The
subject of Early Streamer Emission devices has been analyzed closely by
the Scientific Committee of ICLP and its members. Moreover, the subject
has been dealt with in connection with discussions of papers presented
during the recent year's conferences.
With
this background, and on the basis of the latest results within the fields
of lightning physics and the individual lightning processes, and the results
of field tests, ICLP wish to submit the following information on major
aspects of the subject to the NFPA and their Panel concerning the draft
standard 781 under examination.
1. Unfortunately
the above mentioned function claimed for the operation of the ESE rod
has never been proven to be correct under natural lightning conditions.
Independent researchers have been unable to demonstrate the expected
advantages determined by means of the specified laboratory tests. On
the contrary, the ESE rod and the simple Franklin rod do not show any
major difference in the protection distance and the difference in the
number of flashes to the Franklin and the ESE rods in competition tests.
2. The draft standard
does not clearly distinguish between the different types of discharges:
streamer, cold and hot leader, and whether the discharges are stable
(self-contained) or if they will cease (be extinguished). This is unfortunate,
because each of the different types of discharges has its own set of
properties: current, field-strength, velocity etc. Moreover, for the
specified determination of the "upwards leader initiation time" in the
laboratory in connection with break down tests of the different types
of rods, the minimum dimensions specified are so small, that it is doubtful
whether the initiated streamer develops into a (cold) leader. Finally,
the draft standard does not consider what relationship the streamer
or (cold) leader-initiated breakdown has to the initiation of a stable
hot leader as they develop under natural lightning conditions.
3. The specified
laboratory test does not consider the immense difference in scale for
the laboratory set-up and the actual dimensions in the field. Due to
these differences, the different field conditions in a high voltage
laboratory versus the ones under natural lightning conditions, and due
to the highly nonlinear nature of the different discharge phenomena,
it is impossible in the laboratory to determine the development of a
stable progressing hot leader, as it develops under natural conditions.
In any case the
specified minimum dimension is so small that it might even be impossible
for the streamer to develop into a stable (cold) leader. Finally, even
if it were possible in the laboratory to determine the onset of a stable
progressing (cold) leader, the draft standard specifies an unrealistic
high velocity of the progressing discharge, which has no resemblance
to the velocity of a hot leader as developed under natural conditions.
4. The specified
field qualification test seems not to be adequate for the determination
of the order of merits of the different types of rods when considering
the findings given in comment 1. Apparently, the reason is that the
current specified in the draft standard for the pre-discharge under
natural conditions, does not ensure, that the discharge will progress
continuously nor, if it seems to do so, that a junction with the down
coming leader automatically will follow.
5. The specified
concept for the determination of the protection distance by means of
the Rolling Sphere Method rests on a misconception of the methods. Therefore,
the results determined by the draft standard are incorrect. The position
of an imaginary conducting plane, at a given height of the construction,
before the application of the Rolling Sphere Method, as indicated in
the draft standard [cf. for inst. Figure C-3.2(b) Example of design],
will completely change the original field around the object . The result
will therefore be invalid for the original construction. Thus, the evaluation
of the protection, for inst. for a Franklin rod, will be different depending
on whether it is determined according to the draft standard or the IEC
standard (and the corresponding American standard). This difference
may imply legal consequences when responsibility of a lightning protection
failure will be judged.
6. When considering
the above-mentioned information, and considering that the lightning
protection is a matter of achieving safety, it is evident that the concept
of the ESE rods is inadequate to provide the safety such as defined
in the draft standard. For this reason alone the draft standard does
not satisfy the minimum requirements for a safety standard. Therefore,
the NFPA draft standard 781 should not be accepted.
As a
consequence, ICLP strongly recommends the suspension of the draft standard
completely as it has already been done once before.
Finally,
ICLP wants to express its willingness to provide NFPA and the Panel with
more detailed information if requested.
On behalf
of ICLP
Signed
by:
Prof.
Dr. Ing. C. Mazzetti, President of ICLP
Prof. Dr. Zdobyslaw Flisowski, Vice President of ICLP
Abdul M. Mousa; Burnaby, BC Canada; e-mail: abdul.mousa@bchydro.bc.ca
Reposted
by permission of the copyright holder, Abdul M. Mousa
Aproved for LightningProtection@ONElist.com by Eduardo Rottenberg, E.E.,
and Fredrick Rea O'Keefe, list moderator.
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