Hi Tom,

I just wanted you to know that I found out that you were correct concerning
the need for a ground rod in a separate building. I recently attended some
continuing ed. classes to maintain my license and both instructors brought
that issue up in class without prompting from me. It turns out that it is a
common misconception even among professionals that the equipment grounding
conductor alone will satisfy the code requirements.

As for William Deans; If he had spent half as much time installing that
grounding conductor on the water pipe where the inspector told him to
instead of wasting time trying to find an excuse not to, he would have a
nice, safe, code compliant grounding electrode system. I wonder if the
inspector told him to bond the gas pipe also?


John Grabowski
http://www.mrelectrician.tv



"HorneTD" wrote in message
ink.net...
toller wrote:
"RBM" rmottola1(remove wrote in message
...

William, if you attach the wire to the pipe close to the electric panel
and someone like a plumber,disconnects the pipe between your ground wire
and where the pipe enters the house, and there is a fault current, the
plumber can get electrocuted. I know there are a lot of if's here, but
that's the reason

That assumes
1) the electrical system is grounded to the water pipes, which appears
not
to be the case
2) the ground connection between the electrical system and the utility
and
the grounding rod are both open (as they are many times better path to
ground than a plumber could possibly be)

This is pretty silly, but then that doesn't mean you are wrong.


I'm a Firefighter / Rescuer (FF/EMT) for my community and I have
responded to four different electrical injuries caused by bad grounding.
Two of those were working codes and one of those didn't make it. I
am only one EMT out of the thousands that serve in the nation so I
cannot believe that such occurrences are as rare as some of you seem to
think.

The impedance of two eight foot ground rods driven only the requisite
six feet apart is often over fifty ohms. The impedance of the
underground metal water piping is usually less than ten ohms because it
is part of a network of underground piping that interconnects the
neutrals of all the electrical services in the area. There are still
many water utilities that do not permit plastic piping for service
laterals. It is your electrical inspectors job to know if yours is one
of them.

If you loose the low impedance underground metal water piping grounding
electrode a plumber or water meter mechanic kneeling on a concrete
basement floor may well have a low enough impedance to suffer an
injurious or fatal shock.

It only takes thirty volts to overcome the skin resistance of a healthy
adult and it only takes ten milliamperes to cause a fatal cardiac
dysrhythmia called ventricular fibrillation. If the neutral service
conductor does fail 120 volts is imposed upon the grounding electrode
system. The resultant current flow divides in proportion to the
impedance of the electrodes that make up the grounding electrode system.
If the plumbing pipe connection has been broken by alterations or
repair a human in contact with any part of the grounding system could
well find themselves in deadly danger.
--
Tom H