"Minnie Bannister" wrote in message
...
On 02/23/04 04:01 pm volts500 put fingers to keyboard and launched the
following message into cyberspace:

snip

Also, if you have an underground metal water supply line, it's very
important that you have have an unbroken (preferably #4) bare copper
wire
connected from within 5 feet of where the supply line comes into the
house
routed to the main electric service. Jumper across the water meter if
applicable, and jumper from the hot to cold at the water heater, if
metal
pipes. Any sections of metal pipe that may have been replaced with
plastic
pipe should be jumpered also. Use UL listed/approved ground
clamps/connectors, preferably bronze.

No sign of any wire between the water pipe at any point and the
electrical system ground, and no sign of connection between hot and cold
pipes. Yet I did measure a low resistance ( 1 Ohm) between the pipes on
either side of the water meter (despite the Teflon-taped joints),
between the hot and cold water pipes (after all, they are both conencted
to the water heater), and between the water pipes and the case of the
electric panel.


Years ago, when metal water pipes were used, it was permissible to use the
interior metal cold water pipe as part of the grounding electrode conductor
(not any more). Look for a cold water pipe that is close to the electric
panel, as you may find the connection there that goes from the water pipe to
the panel. One should not depend upon the pipe connections at the water
heater for bonding purposes, use jumpers.

You should try to determine if your underground water supply pipe is metal
or plastic. If it's metal, it needs to be connected to the main electric
service, no exceptions. It may be plastic since you seem to have a ground
wire that comes out of the meter, to a ground rod, then to the panel. If
the water supply line is plastic, you definitely need to bond the interior
metal water pipes to the electric service.


The gas meter and telephone network interface are on the opposite end
wall of the house. The first thing I noticed is that an insulated wire
that comes out of the ground alongside the gas pipe is simply twisted
around it, with the bared end just "flapping in the breeze"; there are
no marks on the pipe to suggest that the wire was ever clamped to it.


I think Dan clarified that that wire may be a tracer wire for locating
purposes, and of course,the gas supply line would be plastic then.


That doesn't sound good. A grounding connection should _never_ be made
to
an _underground_ gas line. However, any _interior_ metal gas line
should be
bonded to the main electric service grounding system. Local codes may
vary.

No sign of a connection between the gas line and the electrical
grounding system either. But the gas line is connected to the water
heater, which is connected to the water line, which appears to have a
low-resistance connection (somehow -- see above) to the electrical
system ground.

That would be a good place to bond all three together. If your underground
water supply line is plastic, you could then run a ground wire from the cold
water pipe nearest the panel, to the panel, which would then bond the hot,
cold, and inside gas line to the electric service.


(The
telephone interface box is just a few feet away from the gas meter, but
the wire that disappears into the ground from it has a different color
insualtion from the one wrapped around the gas pipe, so I don't think
the floating wire is supposed to be the ground for the telephone.)

That doesn't sound good either. There's a possibility that the
telephone
interface box is grounded to the underground gas line. You'll want to
carefully dig that wire out until you find where is goes. If you are
lucky
that phone ground wire goes to a ground rod that is installed as far
away
from the gas line as practical, then that ground rod should be connected
to
the main electric service ground on the other side of the house, again,
preferably with a bare #4 conductor.

I found where the wire from the telephone network interface box goes: it
is connected to a cold water pipe inside the house, which is ultimately
conected to the incoming water supply -- all copper piping, except for
the sprinkler system.


The wire from the telephone interface should be less than 20 ft. What you
describe was permitted 30 years ago and would be grandfathered in. Since
plastic pipe became popular, the connection is now required to be connected
to the underground metal water pipe within 5 ft. of where the water pipe
enters the building. Or connect it to the (GEC) Grounding Electrode
Conductor (the one coming out of the electric meter.) If the ground wire
off the telephone interface were longer than 20 ft. (on a new install) then
you'd have to drive a ground rod at the interface and bond that ground rod
to the GEC. You should be OK the way it is now since yourinterior metal
water lines are intact.

If you have cable TV, it needs to be bonded to the electric grounding system
also.


How recent is the requirement that all grounds must be bonded together?


It's not a recent requirement, can't put a date on it though.


This house is 30 yrs old.

MB