Re: Lightning & Bathtubs

dnoyeB wrote:
On Sat, 31 May 2008 23:33:28 -0400, gfretwell wrote:

On Fri, 30 May 2008 17:20:56 -0500, letterman@xxxxxxxxxxx wrote:

We are always told to never take a bath when it's lightning because of
the possibility of electrocution if the lightning travels through the
metal plumbing. This makes sense. But what if the plumbing connected
ot the tub is all plastic? These days we have PEX, CPVC, and other
plastic pipes supplying the water to the tub, and PVC drain pipes. Since
the tub is not connected to any metal plumbing, is there any danger?

I'm not planning to take a bath or shower during a storm, but I just
heard this warning on tv again, and it got me wondering if there's any
danger with all plastic pipes. It kind of seems like this may be an
outdated warning, if one knows for sure there are no metal pipes
connected.

Mythbusters played with these things in the power company lab. and
figured out all sorts of bad things could happen in a lightnng storm
(shower, phone etc)
The main lesson was they had to lift the ground electrode cable to get
any of these bad things to happen. A properly bonded and grounded house
should be safe.
If everything is bonded you are a bird on a wire or a helicopter
lineman.
The same basic principle is true in your surge protection but I am not
getting in that flame war.

That is totally untrue. Lightning is static electricity, its going to behave differently than your standard A/C 3-phase loop. This is like saying because you have a lightning rod, you won't get struck by lightning. The only thing a lightning rod means is you are less likely to get struck, but if you do, it will be right in the rod.

So a "properly bonded and grounded" house will be less likely to get struck, but if it is, it will be right in the "bond and ground."

I read gfretwell as saying that with proper bonding there won't be damaging voltage between parts of the electrical system. Like a "bird on a wire", or perhaps 2 birds on the same wire that touch each other. With proper grounding (earthing), the voltage of the system to 'earth' is minimized. [But for protection from a direct strike to a house you need lightning rods.]

Myhtbusters disconnected grounding (earthing) so there was dangerous voltage between the system and 'earth'. [The mythbusters earthing was probably much more effective than a house.]


Far as I have read, lightning rods do not reduce the probability of a building being struck by lightning (although some manufacturers make that claim).

--
bud--
.

Relevant Pages

  • Re: surge protection built into ordinary household electronics
    ... Physical Electrical Shock Hazard (Electrocution) ... Ground Fault Interruption ... Component-Level Protection ... not because they are immune to lightning! ...
    (sci.electronics.design)
  • Re: Lightning & Bathtubs
    ... the possibility of electrocution if the lightning travels through the ... plastic pipes supplying the water to the tub, ... saying because you have a lightning rod, ... get struck, but if you do, it will be right in the rod. ...
    (alt.home.repair)
  • Re: Lightning & Bathtubs
    ... the possibility of electrocution if the lightning travels through the ... plastic pipes supplying the water to the tub, ... the tub is not connected to any metal plumbing, ... Lightning is static electricity, its going to ...
    (alt.home.repair)
  • Re: Lightning & Bathtubs
    ... plastic pipes supplying the water to the tub, ... Since the tub is not connected to any metal plumbing, ... I'm not planning to take a bath or shower during a storm, ... which have spectacular lightning storms. ...
    (alt.home.repair)
  • Re: Tonights ride home from work
    ... dielectric than wet wood, but, as you say, if a strike ... A lightning rod is to dissipates the earth's local electrical charge ...
    (rec.motorcycles)