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Re: lightning strike

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During a lightning strike, the lightning is going to
try and find a way to the ground.  This can be through
multiple conducting materials, including piping inside
the house.  If there is gas piping to the fireplace,
that gas piping is connected to a ground rod pounded
into the ground via a rather large copper conductor
right where the gas meter is placed.  

Similarly, any reinforcing steel or anything that
conducts electricity near a pool (metal hand rails,
...) is electrically grounded and normally bonded

Once the lightning strikes, it will run all over the
place going to the ground.  If the soil is not very
conductive, it will follow the least path of
Resistance until it is dissipated.  That means the
lightning strike can be at the ground and still jump
to the house depending the local conditions.

There's a lot of energy there that needs to be
dissipated.  Once it's in the house via the electrical
wiring, phone wiring, water piping, gas piping, etc.,
it can do a lot of damage.  All these utilities are
normally grounded for your electrical safety.  It's a
way out for stray electricity but also a way in.

Paul Blomberg
Phoenix, AZ

--- Andrew Kester <andrew(--nospam--at)> wrote:
> Chris:
> Was this after we had that really bad electrical
> storm roll through C. FL
> last week??
> You said the crack goes from the fireplace to the
> water heater? Is there any
> reason for a water pipe to be near the fireplace and
> then run back to the
> water heater? Does the plumbing all work still with
> no noticeable leaks?
> I am not sure how the electricity traveled, but the
> cracking sounds right.
> The intense heat generated by the lightning may have
> superheated any
> residual moisture in the concrete causing it to
> expand and crack. This
> happened on one of our jobs a few months ago only as
> a result of an
> electrical wiring mistake. They charged up a
> building with 480 volts instead
> of 220 on a super deluxe capacitor (ok, I made that
> up because I don't know
> jack about electricity), anyway, it blew the panel
> off the wall and caused
> an EXPLOSION. Luckily noone was hurt. It blew a
> chunk of the CMU wall off
> and cracked the slab, from arcing and subsequent
> heat. We figured also due
> to heating of the moisture in the concrete. I can
> send you a couple of pics
> upon request.
> Cracks around a pool- could be completely unrelated.
> Do you see any signs of
> fire/electrical heat damage? Why would the
> electricity be flowing in the
> pool slab, maybe through the wiring in the slab?
> (Usually pool wiring is
> buried in some conduit below the slab.)
> Let us know your conclusions!!
> Andrew Kester, EI
> Longwood, FL

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