🚀 go-pugleaf

In article <10269@dasys1.UUCP> aj-mberg@dasys1.UUCP (Micha Berger) writes:
>spector@brillig.umd.edu.UUCP (?) writes:
>>Question from a novice: My house has "two prong" outlets.  I've been told
>>that the center screw and casing of the outlet boxes is generally grounded,
>>so that I will have a correctly grounded outlet if I attach the wire of a
>>"3 to 2 adapter" to the center screw.  How do I (a vertual electronics
>>know-nothing) check to see if this is working in my case?
>
     {{Text deleted}}
>
>Barring lightning, I wouldn't panic about grounding. Especially if your
 ^^^^^^^^^^^^^^^^^  ^ ^^^^^    ^^^^^ ^^^^^ ^^^^^^^^^     
>outlet strip has a fuse / circuit breaker.
>-- 
>					Micha Berger
>
I've watched this discussion go on for a while now and most of the advice
has been good, BUT now to insert my $.02!!

Many if not all PC's and a large portion of commercial grade electronics
have some sort of power line filter to meet FCC and other RFI/EMI specs.
Most of these filters have a pair of capacitors from each side of the line
to "ground". (read chassis)  Modern equipment probably use capacitor values
such that the reactive current to "ground" is less than 0.5ma for 120V
lines. However, I've seen equipment from not that long ago that had caps
as big as .1uF from both lines to ground. When the chassis of such 
equipment is not connected to earth or mains ground, the chassis floats
at about 1/2 the line voltage! I've frequently seen people (who should 
know better!) use "cheater" plugs (3 pin to 2 pin converters, with the 
little ground wire disconnected, or cut off) to "float" some piece of 
equipment, austensibly to eliminate ground loops. This may eliminate the
dc ground loop, but the 60 HZ line current to "ground" is forced to flow
through the signal leads, which usually doesn't help the problem.

There are a lot of items in a home/shop in addition to plumbing and damp
floors, that are directly or indirectly tied to ground, even in older
buildings. A good example is heating equipment, radiators, floor
or wall registers, sheet metal ductwork, etc. It can be a real surprise
to be standing on a floor register in your bare feet and touch a "floating"
appliance. The current may be limited to a few ma. or less, but shocks
are dangerous under any conditions, especially 60 Hz.

A 120V bulb can be rigged up with some care as a test light.  One side
is connected to the ground in question, and the other connected to the
high side of the line (usually a black or red wire). If the bulb glows
brightly the ground is of some value. If it doesn't light or lights
dimly the ground is not good. Compare the brightness when the lamp is 
connected to the ground being tested to when it is plugged directly into
the outlet. Comparative brightness is a good rough measure of voltage
equality, because it varies significantly with small variations in 
voltage. This is *DEFINITELY* only a minimal test of ground integrity.

The best advice is the licensed electrician.

-----Bob

-- 
            Bob Lewandowski
    Domain: blew@tc.fluke.COM
     Voice: (206) 347-6100, Ext. 5368
      UUCP: {microsof,sun}!fluke!blew
  U S nail: John Fluke Mfg. Co. / P.O. Box C9090 / MS 273G / Everett WA  98206