Stray Current

Have I missed something guys?

Is it not a requirement to bond around a meter? The examples given concerning shocks are the exact reason for this bonding.

and as to di-electric couplings. A metallic water pipe that has at leas 10 feet of direct earth contact is required to to used as a grounding electrode.

in other words; you cannot isolate the outside pipes from the grounding electrode system, at least as controlled today by NEC.

as well, if the outside pipes are not bonded, there will always be the possibility of a difference of potential between anything metallic in the house and whatever portion of the water pipe is exposed in the house which would create a hazard. Remember, we are concerned with providing a 0 potential, not neccessarily 0 current.

while corrosion may be a serious problem to deal with, causing an electrical hazard to prevent it is not the way to solve it.

Maybe the plumbing codes need to be re-worked that would require a plastic section for the last several feet of the pipe that comes in to the buildig. That would eliminate our requirement to use as an electrode and it would eliminate currrent flow on the pipe itself.

John, I see you speak to the AC current as a minor cause but in the link, it did speak to the creation of DC current due to the widespread use of electronics. Many of todays electronics do operate on self made DC and so that would be a possibility. In cheaper methods of producing DC, you would have a rough pulsed DC which would induce a DC current into another conductor, especially an EGC in close proximity.

ok i emailed the link to a friend i work with and this is what he replied back, the quoted text is from the link and the other text is his words. do u agree or disagree???

I don't know how old this is, but its flawed at best.
He has some points, but the majority of it is wishful
thinking. For example....
"We are actively soliciting the NFPA to change the
next revision of the National Electrical Code so it
would prohibit the grounding of electrical services to
water lines."
Obviously this creates a hazard to everyone that has a
faucet, sink, hose, etc....and say a electric shaver,
an electric range, a portable plug in radio, etc. The
idea that the situation would never occur where
somebody would touch an electrically bonded surface
and a water line is ludicrous. Not to mention
dangerous...
"We feel that the interior piping certainly could be
grounded to the rod, but all exterior piping should
definitely not be part of this network."
How exactly do you propose to simultaneously prohibit
bonding of water services, yet bond them to the rod?
How will this change anything? Clearly this guy is in
the "electricity always takes the easiest path to
ground" crowd. Anyone whos ever touched a neutral and
a ground at the same time in a light fixture with a
load feeding through knows this is wrong. Not to
mention that this contradicts everything in the first
part of the paragraph.
"Therefore, isolation couplings and dielectric
couplings are being encouraged wherever we can in the
water industry to reduce the problem of corrosion in
mains and deterioration of the infrastructure through
the stray current problems."
If the problem is corrosion in the water MAINS, then
use the dielectric couplings or plastic service mains.
Why petition the NFPA to deliberately put millions of
people at serious risk to save a few man hours
maintaining water lines. What could an agency charged
with the task of assuring electrical and fire safety
have to gain by doing this? Liability? It'll never
happen... Also remember that potential (voltage)is not
always created through unbalanced neutral current, its
also created by long expanses of distance. If it
wasn't we wouldn't have any use for a Megger meter.
For example...the ground potential at my house is
different than the ground potential at your house is
different than the ground potential at my sisters
house, and so on....however, technically due to the
water mains we're all at the same potential. That's
the whole point of bonding. Deliberately lifting that
bond won't necessarily solve a deterioration issue.
Remember that PURE water (H2O) doesn't conduct
electricity, but the water we all drink and runs
through all of our houses is FAR from pure. Its
treated and chock full of fluoride and minerals,
particularly iron (among others) which conducts
electricity.
"We know that our pipe, particularly if it is metallic
pipe, can lose approximately 20 pounds of metal per
year from just one amp of current flowing on the
pipeline in a path that releases the ground off of
us."
...how much pipe are we talking about? 20 lbs of pipe,
or 20,000,000 pounds of pipe? Theres a useless and
alarmist factoid if I've ever heard one.
"We have even found instances where appliances have
been grounded to gas pipes because customers do not
always know the difference between gas and water pipes
in their basement."
That's not the reason. Actually, because of some
oversight in the electrical code, it both requires you
to and prohibits you to bond the gas pipe.
"My distribution people commonly tell me of electrical
shocks when they remove a meter from the water line,
indicating the tremendous risk to them."
If they're reckless, unqualified dumb-asses then they
deserve to get shocked, and the water utility deserves
to pay their settlements out of court. Don't blame
this on the electrical industry.
"We have not yet addressed the electrical shock
hazards from the AC (Fig. 6)"
...No kidding...
"and certainly we have not been able to totally define
that AC current does or does not have a detrimental
effect on the operations life expectancy of a water
line."
I don't think I even need to comment on this one...
This guy sounds like a corporate mudslinger out to
save his industry a buck on the backs of millions of
people who probably pay his salary and definitely pay
for utilities to be maintained. What are my thoughts??

goose it is not leakage or stray current we are discussing. It is "circulating" current that is traveling on the exterior water piping system due to the connection of the neutral to ground bond in every panel and then connecting to the water pipe system that connects to every house. A percentage of neutral current takes the pipe path house to house.

Voltage on a open section of pipe would be very low as mentioned EXCEPT, if there is an open neutral issue at a house panel or meter.

Neutral ground voltage is a product of load with the resulting neutral current and distance from the neutral ground bond which due to voltage drop on the neutral results in neutral to ground voltage. Most single phase residential services have low neutral current and with the water pipe issue have multiple neutral ground connections.

Having said all this I feel this current is objectionable, and should be avoided for a variety of reasons*. The code has a section 250.6 (B) (3) that allows the following install dielectric coupling, install ground rods, bond the interior water pipe.

Additionally what is the main purpose of an electrode in a residential service? Lightning strikes and accidental connections to the utility. The NEC mandates 25 ohm for a single electrode if this is insufficient drive another and walk away. A 25 ohm or somewhat less resistance to earth are they really concerned about this connection? Is the water pipe connection just a fall back to past NEC's that some feel is the "Holy Grail" of ground electrodes.


*Minimize EMF issues which will become a bigger issue (real or imagined) in the future than pipe damage.
Possible damage from lighting strike in one house damaging equipment in another, and while MINIMAL, lawyers do not care about minimal.
The mentioned shock hazard due to a lost neutral.