Electronics Forum / Electrical Engineering / September 2008

I  disagree that it is superior. The circuitry is subject to failure, hence
the instructions to test monthly (you do test all of yours every month,
don't you?)
If it fails and there is no bonding system, you have a lethal situation if a
fault occurs. I am fine with using both methods together, but if I have to
choose one I would rather rely on copper wire for my protection. It is not
perfect, but in my opinion it is much more reliable. If the industry
develops dual redundant self testing GFCI circuits, similar to what is used
in other safety critical applications, then I might reconsider.

This could be true only in circumstances where there is very little leakage
current, and no other sources of common mode current.  I have already found
that RF fields can cause false trips of GFCI, and in certain cases also cause
incorrect and potentially hazardous operation (unless the opening of the
circuit also cuts off the power driving the GFCI circuitry itself).  It is
believable that circulating harmonic currents could do this, as well.  Maybe
GFCIs need to come with a low pass filter.

A combination scheme would be the best.

Here are my thoughts:

Theoretically, one could argue that an individual grounding conductor from
each device back to the main bonding point would be the most reliable, since
nothing that happens anywhere else could adversely affect any other device's
ground integrity. Obviously, this is impractical in terms of the number of
grounding conductors. You grouped things as appliances, raceways, etc, which
is a compromise, and I am not sure it accomplishes anything. It reduces the
number of conductors, but is still probably impractical. I am of course not
addressing systems such as hospital patient care with isolated grounds, etc.

Current industry design practice in the US is to properly bond every exposed
surface to a common egc system. Certain requirements, such as using pigtails
at receptacles and switches, prevent the most common possible interruptions
of that grounding system, but do not eliminate every possibility.  Using
green wires instead of relying on conduit connections alone is a big
reliability improvement. I have not seen any studies or statistics proving
that our current industry practice is inadequate based on the number of
electric shocks/electrocutions on properly grounded systems. These accidents
more often appear to be the result of improper grounding.

The "double framed" appliance concept is an interesting one, but certainly
not one that can be universally implemented. I am not sure it is necessary
if you prevent exposure to the live conductor to begin with. Remember that
typically a fault occurs within the appliance. We already have double
insulated appliances which accomplish the same thing except when they get
wet! In that case, the "double framed" would offer an advantage  of a
grounded barrier to prevent a conductive water film on the outside.

Given a choice of using solid copper wire or a GFCI to protect a receptacle
or appliance, the solid copper is preferred over an electronic circuit. The
GFCI is acceptable practice where there is no copper ground (ie. older
two-wire systems), as it is better than no protection at all.

The bottom line is that I believe the current grounding practices are
adequate, when PROPERLY executed.  I have seen older systems that were well
grounded because someone took the care to do it right. The biggest issue I
see is when poor workmanship or improper installation compromises the
grounding system. Even in industrial environments there are
"do-it-yourselfers" who don't have a clue. You won't eliminate this type of
problem by designing a "better" more expensive and complex system that won't
get done right anyhow.