To follow up previous post, I also saw a note from Lightning protection drawing indicates " where the metal bodies 3/16" or thicker do not require air terminal ", I am doing the research on nfpa-780 to see where does this rule comes from. Any comments will be appreciated. Thanks!
Lightning Protection - Air Terminal
- Thread starter anbm
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ron
Senior Member
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You will find it in NFPA 780.
The concept is that 3/16" steel will act as a terminal. It needs to be bonded like any other air terminal.
The concept is that 3/16" steel will act as a terminal. It needs to be bonded like any other air terminal.
jimday
Member
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- Northern California
check 4.19, 4.20 and 4.20 regarding metal bodies....
weressl
Esteemed Member
4.8.8.1
Chimneys or vents with a metal thickness of 4.8 mm
(3⁄16 in.) or more shall require only a connection to the lightning
(3⁄16 in.) or more shall require only a connection to the lightning
protection system.
6.10.1
Heavy-duty metal stacks having a metal thickness of
4.8 mm (3⁄16 in.) or greater shall not require air terminals or
4.8 mm (3⁄16 in.) or greater shall not require air terminals or
down conductors.
7.1.2.1
Metallic structures that are electrically continuous;
tightly sealed to prevent the escape of liquids, vapors, or gases;
and of 4.8mm(3⁄16 in.) thickness or greater to withstand direct
strikes in accordance with 7.3.2 shall be considered to be inherently
tightly sealed to prevent the escape of liquids, vapors, or gases;
and of 4.8mm(3⁄16 in.) thickness or greater to withstand direct
strikes in accordance with 7.3.2 shall be considered to be inherently
self-protecting.
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