On 4/3/2011 9:48 AM, Carl wrote:
> Altho the 4 wire has been SOP in industrial sites for ages it is a result of
> nanny state busybodies
NO! Those "busybodies" to which you refer were smart electrical
engineers who understood God's laws of physics, understood them in the
context of "the big picture" of how buildings are wired and power is
used, and realized the negative implications of allowing the green wire
to carry load current, both in terms of electrical safety and electrical
NOISE. Their work was written into the National Electrical Code, a
model code that has subsequently been adopted by most local governments
in North America..
> Before your dryer ran the 120V motor and SS LV transformers between the hot
> side and a neutral/ground and it worked fine for 60 or so years with a 3
> wire feed.
"Worked fine" means to you that the appliances worked and nothing burned
down. To me, it means that any noise generated in the power system by
the appliance gets radiated by the wiring to the appliance, because the
return path for current is not the neutral that runs in parallel with
the hot conductor, but rather the green wire AND ALL OTHER GROUNDS
running in parallel with the green wire, like the plumbing system. This
causes electrical noise to radiate from that wiring like any other
antenna, and for a magnetic field to be created that couples into low
voltage wiring to put hum into connections between our computers and our
radios. I don't consider that "working fine."
73, Jim Brown K9YC
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