| Charles Perry 2006-04-15, 3:21 pm |
|
"Beachcomber" <invalid@notreal.none> wrote in message
news:4441288a.1249281@news.verizon.net...
>
> One of the reasons I posted these two articles is that, in my
> research, I found it fascinating that there could be so much strong
> emotions amongst professional engineers in the arguements for and
> against ungrounded vs. grounded distribution systems.
>
> Apparently, in the US at least, the split also goes along with the two
> regulatory bodies NEC and NESC, that you describe and more roughly,
> splits the interests of utilities vs. the safety and well-being of
> homeowners and farmers.
>
> My concern is with the reinforcement and codification of bad policy.
> For example, as one of the papers pointed out, NEC standards for RV
> vehicles were apparently just plain wrong in the 1950's when the
> neutral was allowed to served as ground and people were electrocuted
> just by touching the metal frame of their RV and standing on damp
> ground.
>
> Apparently there were similar problems extended to marinas, which have
> their own unique problems with grounding issues. It took years of
> study before the regulations "made it right" with a safer insulation
> and a fully grounded system. In the meantime, how many unnecessary
> electrocution deaths occured to swimmers in all those early years when
> inferior and lax regulations were in place?
>
> Beachcomber
The problem with your arguement is that the current system, as applied to
medium voltage distribution lines in the US, is NOT killing people. Some
stray voltage problems exist, but they are usually localized problems.
These stray voltages are not killing people. They do scare people but they
don't kill them.
In many of the stray voltage cases we have studied, the high levels of 3rd
harmonic current in the neutral have been a major contributor. These
currents are created by electronic loads and since they are triplens, they
add, rather than cancel, in the neutral. I propose that the US adopt a
European style regulation for all, and I mean ALL, electronic equipment
requiring power factor corrected power supplies. Fewer harmonics, better
power factor, everyone wins.
Charles Perry P.E.
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