Bonding a Truck Scale....

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Fulthrotl

~Autocorrect is My Worst Enema.~
i have a customer who has a truck scale.

they are concerned with lightning strikes taking out
the load cells, etc. they want bonding to a ground rod(s).

next to each end of the scale is a 15' tall piece of 4" GRC
used as a mast that scale displays, RFID card readers, etc.
used with the scale are mounted to.

so the devices are mounted on the mast, which goes about
3' into a poured concrete base.

80' scale, four 20' sections. mast at each end, with equipment
on it.

so, here's what i was going to do... a bond from a lug on
each mast, ran underneath the scale, with taps going up
to each floating section of the scale, bolted to a lug on the
side of it. everything terminated in hypress, including the
taps to each floating section.

two 8' ground rods, one driven near each mast, tied into this bond
as well.

to prevent any ground loops, a ground wire from the equipment
grounding bus in the card reader mounted on the masts, down
to the lug bolted on the bottom of the mast.

i was planning on using #2 copper for all of the bonding.

now, here are my thoughts....

is #2 adequate for something like this?

the most likely target for a lightning strike is the mast.
is it better not to tie it into the bond wire, and leave it
standing apart, rather than bond the scale directly to
the thing most likely to get hit?

appreciate any feedback on this.. thanks.
 

Smart $

Esteemed Member
Location
Ohio
I suggest isolated strike terminals (at least 4, one at each corner) and isolated down conductors to a ground ring with or without additional electrodes and not bonded to the structural metal or EGS. Do any scale EGS bonding completely separate and isolated. Some galvanic crossover may be unavoidable. Try to limit crossover to at or below the ground plane (i.e. earth grade).

https://www.erico.com/public/library/fep/LT1462.pdf

PS: I'm a novice in the field of lightning protection so take my recommendation with a grain of salt and nothing more... :D
 
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