On Tue, 14 Apr 2009 10:27:09 -0400, Joseph Gwinn
wrote:

I saw this article in The New England Journal of Medicine. Here is the
URL, unfortunately behind a paywall.

http://content.nejm.org/cgi/content/short/360/13/1363

The gist is that a danish doctor had a patient who was getting
inappropriate cardiac shocks from an ICD (implantable cardioverter-
defibrillator) while in the shower, which turned out to be due to bad
house wiring causing a 50 Hz leakage current from showerhead to floor
drain.

A current of 3.5 to 4.0 milliamps is not usually felt, but can spoof the
ICD, which looks for such signals lasting about 300 milliseconds.

This would be easy to check with a voltmeter. And to prevent by
running a ground wire from showerhead to drain pipe.

I've seen it and fixed it. No ICD triggers, but the sensitive
people felt it in the shower and complained. Took me a while to track
it down.

Combinations of idiocy. They had an open Neutral wire and a
faked-in Neutral wire headed out to the wellhead. 2 HP submersible.

Now this wouldn't be a problem normally, since the well is 240V and
only time there would be a load on the Neutral is when they were
working on the well and wanted to use 120V power tools or a light.

But then they tapped off the well for 120V lights and appliances on
a semi-permanent residence tent - they saw a white wire and figured
they were solid.... And all the unbalanced Neutral current was going
through the water to find a ground, and made it up the water line all
the way to the shower heads in the permanent building.

Had to re-pull the power lines (including fresh Neutral and Ground)
all the way out to the well, and of course the problem vanished.

-- Bruce --