I can't find a good solid ruling for this one.
Are phone lines grounded locally at the house?
The configuration at my house has the main phone line coming off the pole,
down to a junction box, where 2 phone lines leave and a single ground wire
connects to the cold water plumbing.
I can't find any definite answers as to whether or not that ground wire is
required, desired, or useless. The intent is on replacing the whole setup
with CAT 5E (seeing how it's just as cheap as CAT 3 or phone cable) and
re-routing the wires, but I don't know if I need to keep the ground wire.
It looks like pretty standard 14 gauge wire, in a grey sheath.
The ground wire is from the surge protector in your Dmark. You need
If you don't have this protection it will ground itself through your
modem and PC. That is not a good thing in a smoking sort of way.
Alright, I'd better call them then.
The whole thing started while I was sheetrocking and insulating the
basement. The previous owner/and or phone company rather than drilling
holes into the studs, took a chisel and cut a "V" notch on the surface of
the stud so that the sheetrock would lay flat. So I'm looking at their
handywork and wondering how I can re-route those wires - when I discovered
that one of those grey wires wasn't a phone line - it was a ground wire.
Now I'm wondering if I can route the ground wire to my panel instead and/or
Alright, Qwest here I come. I'm sure it will take about a week to
sufficiently explain my question to them so that I get an intelligent
Old (older than every poster here) demanded the phone to be earthed
to a water pipe. That is no longer acceptable. Phone must now be
earthed to an electrode also used by cable TV and AC electric. Code
also says that wire must be 12 AWG. Most use 10 AWG wire. Code also
says that earthing wire must be short. That required to meet 'human
safety' code. For transistor safety, that wire from demarc (NID) must
be 'less than 10 feet', separated from all other non-earthing wires, no
sharp bends, no splices, not inside any metallic conduit, and should be
as short as practicable. These include post 1990 code requirements.
Same rules also apply to cable TV and AC mains earthing wire. All
earthing wires should remain separated until all meet at their common
earthing electrode. If it does not exist, you should install the
earthing rod (for AC electric) before the telco comes out. You want
them to use your 'better' earthing. Else they may install one that is
insufficient (too short).
Only other ground for telephone wire is where that wire enters the
telco's CO. However AC electric must be earthed at your earthing
electrode AND at utility's transformer.
While inspecting, also confirm a safety ground wire from breaker box
to water pipe is still connected. Best attached at a point where water
pipe just enters the building and so that an earthing connection does
not pass through any soldered connections. Your gas company may also
demand same connection to gas pipe; a requirement that varies with
natural gas companies.
Most important reason to confirm ground wires and to route them deep
enough so at to not be pierced by a nail - human safety. Do those
inspections while it remains convenient.
Why would this be? Sometimes it might be necessary to use metallic
conduit to protect the earthing wire from physical damage.
Given that the main panel/disconnect will have a grounding bar where
the Grounding Electrode Conductor terminates, is it good practice to
run the cable TV and telephone earthing wires directly to this grounding
When run in steel conduit, the wire through the steel acts as a choke
and can significantly raise the impedance of the earthing wire. As volt
notes, the NEC requires the conduit to be bonded to the earthing wire at
each end so the conduit acts as a conductor in parallel to the earthing
Connect them to the grounding electrode conductor close to where it
leaves the service.
Well, I have both a bare Cu #6 Ufer ground coming out of the concrete
foundation and a bare #6 GEC that goes to a ground rod and the
metallic water service. They are both connected to the ground bar in
the main disconnect. A few questions:
Is it OK to a use a bare #10 for the telephone/cable ground? You
suggest that this wire should be clamped to one of the bare Cu #6
conductors, which one? Why is this better than running it to the
ground bar in the main disconnect?
Thanks for the advice.
The NEC says insulated, but not the most important issue. Minimum size
#14, #10 is good.
The Ufer ground, it is really good. (Underground metal water pipes are
good too, but likely farther away. Ground rods are better than nothing.)
[With a Ufer ground you shouldn't need a rod.]
I believe the ground bar is not one of the allowable points of
attachment in the NEC.
And IMHO: It is better not to run the conductor in with power wiring.
Through the ground bar requires an extra connection in the path to the
Good information except the IEEE guide on surges and surge protection at:
(guide page 28-29) recommends the NID (and cable protector block) be
mounted close to the electrical service, and their ground wire be
connected to the grounding electrode conductor from the electrical
service close to the panel. With high surge currents there will be
significant voltage drop on the wire to the grounding electrode (the
wire will have a much higher impedance at lightning frequencies than its
DC resistance). With separate wires to the grounding electrode, that
voltage will appear between the power wires and the telephone wires and
may damage equipment connected to both. When the NID is connected with a
short path to the power system neutral-ground bond, the phone and power
wires will rise together.
Old practice often connected the NID ground wire to a nearby water pipe.
When electronics is connected to both power and telephone wires that can
produce failures. I moved mine to the grounding electrode conductor (but
now I will be looking for thugs - thanks Jim). The NEC now allows
connection to water pipes only within 5 feet of the entrance to the
We have Verizon FIOS which comes in on fiber optic cable. The ONI
(optical network interface) uses power and I believe uses a grounded
(3-prong) cord -- thus, it is no longer attached to a long
exterior metal wire (i.e. think antenna) and seems analogous to any
interior low voltage wiring system like an alarm.
So does this situation in which the interior telephone circuit is
literally optically isolated does the code still require that the
demarc be bonded directly to earth ground?
Interestingly - our gas company specifically WARNS against bonding the
gas entrance to ground (and will remove it if they see it). I have
heard that some gas companies purposely run a small current on the
external gas pipe to prevent galvanic corrosion. In those cases, the
internal piping (which often is grounded to appliance ground) is
isolated from the street piping via a rubber gasket of sorts.
Optical network interface electronics still connects to AC mains. AC
electric is equivalent to an antenna connected to optican network
electronics. That incoming wire must be earthed where it enter the
building to protect optical network electronics..
FIOS installations appear to have some earthing. Cannot say why with
certainty. But an optical cable has a conductive wire within it. A
conductor so that undersground optical cable can be traced before
excavating. Have observed something from optical cable connected to
earthing. But I did not inquire as to what or why.
Some gas companies want interior gas lines bonded. Others do not.
You must conform to your gas company demands. However that gas pipe
gets bonded anyway when furnace or other gas appliances also use
electricity. IOW if building earthing is not provided, then (as
happened in one dwelling) building might use gas line to obtain a
return ground - may use that pipe as an alternative neutral wire.
Fortunately no one was home when a gas line gasket eventually broke
down; house exploded. Just another (and rare) reason why all
'conductive' utilities should share a common earth ground.
Agreed. That's why I have whole-house surge protection right at the
If that wire is connected to the chassis ground and if that in turn is
connected to the ground prong in the plug, then it should be properly
grounded (and surge protected) in the house. If that electrical signal
is just hanging there isolated from my house wiring then there is not
much I can do about it since I can't access it...
Agreed. I asked my utility and they said "DON'T BOND IT"...
Wire has impedance. That impedance is irrelevant to 60 Hz AC
electricity; grounding that is for human safety. That same ground wire
has too many sharp bends, splices, and bundled with other wires.
Impedance is excessively high for transient protection. Bundled with
other wires, it may even induce transients on those other wires.
Earthing for electronics protection demands other precautions such as
no wire splices, no sharp bends, not inside metallic conduit, separated
from other wires, and especially short distance. AC wall receptacle
safety ground violates principles required for earth ground.
However, when transients are earthed at a building entrance (ie the
'whole house' protector), then higher impedance of interior wiring adds
to appliance protection. This separation and impedance is why better
protected facilities put a protector at earth ground AND distant from
For earthing each utility in a residential dwelling, each utility
should make a less than 10 foot earthing connection - that wire length
is critical. Therefore utilities enter a building at a common location
to have a short earthing connection to a common earthing electrode.
For earthing (and low impedance), the ground connection must be short -
and other factors.
It might be noted this what the Mythbusters had to disconnect to make
the "lightning kills you through the phone" myth wr. With the ground
connected, nothing happened. With it disconnected they had all sorts
My experience is only with computers and surge protection. I know
losing the bond between the phone and the power will blow modems,
system boards and power supplies.
I always thought phone lines were grounded internally through the wire
leading to the pole. Actually that's why I asked, I found too many people
referring back to the grounding on the pole but never mentioning the
grounding on site.
More accurately, the "protector unit" for the service is connected to an earth
ground. 14-gauge used to be the norm. 12 was used for years. It's now
That sounds right. If done to BSP (old Bell System Practice) specification,
there should be a tag attached to the ground connection at the electrode
(water pipe, ground rod, etc). It says something to the effect: On pain of
death, thou shalt not remove the ground. It is enforced by the same thugs
that enforce the mattress tag removal ban. <g>
Only until a direct, or near-direct, lightning strike.
It doesn't make sense to connect Cat 5e wire to a "Cat 2-1/2" network. Cat 5e
works fine for POTS (Plain Old Telephone Service) but is certainly overkill.
It's NETWORKING wire (ethernet, yammer, yammer).
Uh, Cat 3 *IS* phone cable. :)
You need to KEEP IT.
If re-doing the system, I'd go 10-gauge, or at least 12.
I have encountered MANY services where the ground wire had NEVER been
connected, some as old as 20-25 years. I declined to ask the customer if they
had had to replace much/any of their equipment over the years.
I have found services bearing the above-mentioned tag with the ground clamp
(and tag) "flapping in the breeze" (disconnected). Telephony gets no respect
The "protector" at the phone entrance is NOT designed to clamp most surges -
just the *HUGE* ones, like those delivered with a direct/near-direct lightning
strike or a power line coming down across a phone cable or drop.
I once encountered an old (restored, fine) farmhouse that took a direct strike
of lightning. The charge blew the protector housing off the outside of the
home. Half of the housing was 50-feet away. I never found the other half.
On the inside of the home, the bolt blew a 2-ft gaping hole in the lathe and
plaster as it passed between a phone jack and electrical outlet across the
The charge travelled along the underground "drop" (buried service wire) about
250-ft out to the road. There it blew apart a 25-pair splice module,
interrupting service to about 20 subscribers beyond.
This protector WAS grounded, for all the good it did. With a direct strike of
lightning, ALL bets are off.
You want your protector well grounded. Trust me.
Top posted for closure
I really appreciate the response for this. I wasn't sure why that ground
wire was there so I figure I'd better ask before moving it. I can leave it
in its current position, bonded to the pipes, as the pipes are bonded to the
panel ground, this would make the phone ground the shortest it can be -
otherwise I'd have to route the phone ground wire to the other side of my
house. But at least now I can drill the studs and put up nailplates for
protection and peace of mind that I'm not gonna take out my phone service
with an errant nail in the wall.
Just for comparison, the ROMEX was done in the same fashion, that was
corrected as soon as I uncovered that little piece of handywork.
As to CAT 3 being phone cable, sorry I'm a computer systems architect the
word CAT 3 means networking to me. Besides I thought CAT 1 was phone cable?
Before plastic pipe, that's the way grounding was done. Your
installation is grandfathered. While using the interior metal water
pipe as a grounding conductor is no longer permitted by NEC today, even
for telephone or cable, as long as nobody comes along and replaces the
interior metal pipe with plastic without jumpering it, you're OK.
Check to make sure the water meter is jumpered and also the hot to cold
at the water heater. In fact, there are still a lot of houses where
the electric service grounding was done the same way as your phone
grounding. The NEC restrictions against using interior water pipes for
grounding applies to Residential only, because of the availability and
common use of plastic pipe and popularity of DIY. Industrial and
Commercial electric services are still permitted to this day to use
interior metal water pipes as a grounding electrode conductor for an
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