In article ,
Ken Bessler wrote:

I'm planning on buying a Radio Shack outlet tester (22-141, pg 238 of
the last catalog) - if it shows my outlets are configired properly, I plan
on running a heavy insulated ground wire from the outlet to the pipe (8").

Does this sound right to you?

I would advise _against_ doing this, for a couple of reasons.

One is that the Radio Shack tester can detect certain forms of
mis-wiring, but there's at least one which it cannot detect. This is
one in which you have a three-wire outlet, hooked up to a two-wire
power feed (one which doesn't actually have a ground), and the
installer simply wired the "neutral" and "ground" screws together at
the outlet.

To a simple static-voltage-based tester (such as the Radio Shack one
appears to be) this outlet will test out as "good" - there will be 120
volts between hot and neutral, 120 between hot and ground, and zero
between neutral and ground.

However, this sort of outlet does _not_ provide a true safety ground.
If you start drawing a large amount of current through the wire (from
this outlet or from another on the same wire), both the "neutral" and
"ground" contacts will be pulled several volts away from ground by the
I*R losses in the neutral wire. If you've got your equipment chassis
"grounded" to this outlet, the chassis will be pulled up away from
ground - this could present a shock hazard. Also, you can end up with
some portion of the power return current (back to the neutral
connector at the breaker box) flowing where you don't want it...
through your equipment chassis, your hot-water pipe, your
antenna-cable coax braid, etc.

Proper testing for a neutral/ground crossconnection may require
physical inspection of the outlet. It can, I think, also be detected
by measuring the voltage between the neutral and ground pins at an
outlet, while drawing a heavy current (e.g. a 1500-watt space heater)
through the other side of that outlet. If the outlet is wired
properly, you _should_ see at least a volt or so develop between these
two pins - if you don't, it may indicate a neutral/ground crossconnect
at that outlet.

The other reason I'd discourage wiring the power-outlet ground to your
hot-water-heater pipe, is that the National Electric Code doesn't
permit this. If a short circuit occurs somewhere on this circuit, it
would cause your water pipes to carry some of the current back to the
house ground, and this could result in a shock hazard for anyone in
contact with the pipes (e.g. somebody in a shower or tub).

As I recall, the electrical and plumbing systems really should remain
electrically isolated from one another _except_ at a single "bonding"
point. This ensures that the plumbing system cannot carry
ground-return currents, if a fault occurs in the electrical wiring.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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