The code says water pipe 'earthing' may be performed but
that water pipe 'earthing' is not sufficient. That earthing
being different from the still required 'bonding a water pipe
to breaker box' so as to remove electricity from the pipe.
Function that removes electricity - bonding - is required even
though water pipe (alone) is no longer sufficient for earthing
function.

Due to installation of plastic pipe (during repair), some
jurisdictions now require a dedicated ground wire (ie. 6 AWG)
to pipes that connect to steel bathtubs. Concept is that an
electrical wire anywhere inside walls could fault to tub or
pipes (water or drain). Tub or pipe having been electrically
isolated because plumber made his repair; creating a potential
electrical hazard.

Concept that applies here and to rest of discusson: plumber
is not expected to install protection from a hazardous
electrical problem. Electric should be installed so that
plumber cannot create a hazard. My opinion is that this
dedicated tub safety ground should be required for all metal
bathtubs regardless of whether plastic does or does not
currently exist; because potential danger (created by
existence of CPVC in Home Depot, et al) is significant.

Even when city water enters an 'all CPVC pipe' house,
inspector still wants that less than '10 foot of copper pipe
from city water' to be bonded to breaker box. An electrical
fault to that few feet of exposed, interior copper pipe is
still considered hazardous. An electrical fault might even
occur underground and outside the building. Therefore short
copper pipe still must be bonded to electrical box.

Using that principle, a metal pipe buried 40 feet to remote
outside bib also should be bonded. I can appreciate why both
that city water pipe and '40 foot pipe to bib' should be
bonded if someone inside building could touch a potentially
electrically hot pipe. But my guess is that 40 foot pipe is a
classic case of local code interpretation.


Strongly believe that all metal bathtubs even in a house
that is not CPVC should be bonded to breaker box. Like the
idea that incoming city water should still be bonded even if
house is all CPVC - for human safety. Not sure if 40 foot
outside pipe is required, by code, to be bonded to breaker
box. But do appreciate why an inspector would also want pipe
bonded. Electrical faults do happen in earth and outside of
building. Such faults to a '40 foot pipe to bib' in a
backyard would be less likely to harm humans as compared to
electrical fault out beneath the street.

To again make original point clear because 1) it is
necessary for human safety (even if rest of house is CPVC)
and 2) it is so often missing in maybe two out of ten older
homes. That breaker box connection to water pipe 'less than
five foot from entering building' is still required. Pipe
must be bonded to breaker box so as to remove electricity
from pipe; so as to cause circuit breaker to trip.

Tom Horne wrote:
Are you saying that you did not mean that "water pipe earthing is
not required." If that is true then we have no disagreement. My
concern was and continues to be that an ordinary DIYer might read
your post and take that meaning. As long as we agree that in
areas that have adopted the US NEC you must attach a conductor to
an underground metal water pipe that is sized in accordance with
250.66, is free of reversible splices or joints, is connected
within five feet of were the piping enters the structure, and
terminates on the service equipment enclosures bonded buss bar
than I don't care what we each believe the purpose is. I just want
to avoid this thread misleading someone into making a dangerous
mistake.

I would like to ask you to think about a question. In a house
that has an underground metal pipe that; serves only a yard bib
used for gardening, the underground piping is forty feet long,
and it changes over to CPVC (plastic) piping just inside the
basement wall; do you connect any conductor to that piping? The
house has no other metallic piping and I mean none. If you do
connect a conductor to that piping what is the purpose of that
conductor?
--
Tom H