Speaking of ground rods -
I had a 'little' incident with a tree that resulted in the severing of the
neutral feed (1440 volts) to my house or at least the transformer to my
house (and a couple more) - don't ask!
The tree brushed the hot wire on the way down and popped the breaker at the
sub station. That breaker was programmed to try and re-connect and
re-connect it did. Much to my suprise the house was up and powered as if
nothing had happened. ALL the ground return from the transformer and the
house (and the neighborhood) was returning through *the ground*.
Although everything was working normally I knew I had to 'fess up' and face
the music. The 'music' in this case meant bringing in a crew by helicoptor
(no roads in this area - an island to boot). Think $1000.00/hr for the
chopper alone. There is no hiding from the wrath of the power company (BC
Hydro) in this situation. My honesty actually saved my ass. Owning up earned
me a place in history as no one had ever done that before. The local manager
allowed as "folks always tried to plead innocent - but, in the end we
*always* caught them". In my case I realized that the pattern of fallen
trees pointing away from a newly installed Satsllite dish might just prove
embarassing.
The power corp buried the minor fix in a bogus meter mixup and it cost me
not a single dime - and no - I wouldn't get off that easily if I screwed up
again.

Regards
Ken (boning up on his trig in case I have to calculate the arc described by
another falling tree in the vicinity of power lines,)


"ATP" wrote in message
.net...
Gary Coffman wrote:
On Sat, 26 Jul 2003 05:07:09 GMT, "Justin"
wrote:
Note the neutral WILL NOT be connected to the shop ground rod. I
found several nice new, sealed 90' rolls of 2-0 at the reclamation
yard for $25 each last year. Regulations in my area are such that I
don't have to have inspections. Does anyone see a problem?

Why not connect the neutral to the shop ground rod?

Just wondering what the reason was...

The Earth isn't a very good conductor. If you connect to Earth
in two different places, a voltage will exist between the two points
(typically on the order of 25 volts per amp of current in the ground
path). So if you have about 4 amps of fault current, things attached
to one Earthed point will be elevated about 100 volts from the other
Earthed point. That's a potential shock hazard. By connecting to
Earth at only one point, this situation can be avoided.

Gary
In this case it appears that he is connecting the grounding conductor to
the ground rod in the shop, just not bonding it to the neutral. One of the
reasons for this requirement is so that the grounding electrode conductor
does not function as a parallel neutral return or even worse as the main
neutral in case of a lost neutral. This is particularly bad if metallic
conduit is serving as the grounding conductor, because the connections
will
get mighty hot with sustained amperage going through them.

WRT to the ground rod controversy, it is very complicated and some of it
is
beyond me, but I have seen problems with elevated neutrals connected to
copper plumbing systems serving outdoor spigots. People who used the
spigots
while standing on the wet ground with bare feet were getting mild shocks.
There was a small but significant potential difference between ground rods
connected to utility pole neutrals or the service neutral and any driven
ground rod 10' away, which varied continuously and I suspect was related
to
voltage drop on the neutral of the somewhat inadequate utility
distribution
system. In this case the people were "earthed" with their feet, and at a
lower potential than the service entrance neutral or the copper plumbing
bonded to it.