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Grounding a Phone Line

Posted by tchp (My Page) on
Fri, May 9, 08 at 19:52

Qwest Communications is installing a new external phone hookup box on the outside of my house, since the existing box was 40 years old. The technician is telling me that he is required to ground the phone line to the same ground as the house wiring (the old phone box had the line grounded to a hose bib, and he said they cannot ground the phone line to bibs or water pipes anymore). I asked why I can't just drive a new grounding rod into the ground so that the phone line will have its own grounding rod, and he said he could not do this either -- that the phone line had to be grounded to the same ground as the home service panel. Can anyone tell me why this would be the case, and why I cannot have a phone line grounded on its own grounding rod? My house was built in 1963, and is grounded to a cold water supply copper pipe, and the technician says he cannot ground the phone line to that either. Getting a simple phone box installed is making it sound like I am going to have to run a new solid copper ground wire from my service panel to a new ground rod outside, and then ground the phone box to this same rod. It sure seems bizarre to me that I can't just put in a new rod just for the phone line.


Follow-Up Postings:

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RE: Grounding a Phone Line

Have him install the phone box near your electrical service entrance, that way he will be real close (next too??) a ground that meets his needs.

BTW, I hate Qwest.

:)


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RE: Grounding a Phone Line

Unfortunately, it looks like even if he does install the box near to my electrical service entrance, the existing ground for the house (a cold water supply pipe) will also not work to ground the phone line, according to him. I may have to redo the grounding for the service panel by installing 1-2 grounding rods outside, and then wire the service panel to them. Then he can ground the phone line to one of those rods. But that puts the phone box on the complete opposite side of the house from where the phone line comes in from the street. The whole thing would be so much easier if I could just put in a separate grounding rod for the phone line at that end of the house, and be done with it. At this point I would like to know if anyone has ever even heard of it being required that a phone line has to be grounded to the same grounding rod as the house, or if this guy does not know what he is talking about at all.


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RE: Grounding a Phone Line

The phone line is required to be connected to the power grounding electrode system by no more than 20 feet of wire. There is an exception that allows a separate communications ground rod to be used when this is not practical, but the communications ground rod must be bonded to the building's power grounding system. The phone company or your local AHJ may have their own requirements which may differ from the NEC.

The NEC can be viewed online at the NFPA web site. Article 800.100 covers grounding of phone lines.

Here is a link that might be useful: Online NEC


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RE: Grounding a Phone Line

Thanks, that helped clarify things.


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RE: Grounding a Phone Line

"The technician is telling me that he is required to ground the phone line to the same ground as the house wiring".

I must lead a sheltered life, or else the phone companies I have dealt with(Contel, GTE,Alltel, Windstream, AT&T, and many independents) have a much better customer service philosophy than Quest appears to have. I have never heard of an instance where supplying a proper ground becomes the customer's issue. The typical response around here to a technician's statement like yours is, "It looks like you have your work cut out for you, good luck. Please let me know when you have the phone back on."


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RE: Grounding a Phone Line

Congratulation you have a phone guy who actually know what he doing. He is wanting to do it the proper way. Most of them just pound their own ground rod and leave.


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RE: Grounding a Phone Line

Drop another ground rod at the line interface box under the exception. Then then connect the new rod to the old ground.
It would be better to drive another rod for the electric service since it has been required for many code revs to have both a primary and at least one secondary electrode. You do not need two rods if the water pipe is the primary (and if it is metalic and 10 feet long in contact with the earth it MUST be the primary).

While you are not normally obliged to upgrade to new code revisions, new work must comply with the revision in effect when the new stuff is installed.

If that means a secondary grounding rod for the TELCO to meet the rules you need to put in the rod and bond the TELCO rod to the power rod.


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RE: Grounding a Phone Line

Right, the qwest tech. knows what he's doing and is trying to do it the right way. Be it power, catv, phone, water, they should all be "bonded" or grounded together for safety, insurance(lightning strikes whatever), and noise reasons. Your're making a mountain out of a mole hill...if practical, he should run a ground wire to a cold water pipe(preferrably) and as a LAST resort, if ground options nil, then he should drive a ground rod.


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RE: Grounding a Phone Line

FYI, I don't think the ground on the phone line actually grounds either of the incoming wires. I believe it's only the ground side of the lightning protection.


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RE: Grounding a Phone Line

I think phone service from Qwest works best if first struck by lightning.

I have known some acct. reps. on which I like to try out my assertion.

But I digress...


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RE: Grounding a Phone Line

I am a sound engineer and not a telephone specialist but...
I think this grounding pattern is referred to as a "Star" ground. All branches of the star meet in the center (ground rod).
This eliminates noise from ground differential (voltage difference -less than a volt- that arises with multiple ground paths. A symptom of which is to feel the tingle of low voltage current when touching both grounds. It also minimizes 60 hz hum caused by ground-loops. If you have more than one ground (rod) certain noise signals are prone to looping around in circles.

I hope this is helpful...we're all in this together.


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RE: Grounding a Phone Line

Sorry, Harry, there's no problem with ground loops and multiple paths.
SOLAR POWERED is right. Neither of the phone wires is grounded (and woe be it to you if one side does become grounded). The thing that is grounded is the lightning protector which only conducts when there's sufficient potential (more than the 90V that is the typical phone max) between the lines and ground.

That ground needs to be connected by a direct path to an acceptable ground. The rules have been pointed out early by wired_lain and Brickeye.


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RE: Grounding a Phone Line

HarryTuttle hit the nail on the head. There could be
a difference 'in potential' between all of your ground rods. They should all be tied together. By 'in potential', I mean to say that there could be a difference to "TRUE GROUND", between ground rods. For example:
a rod driven in sand does not have the same grounding
as a rod driven in clay. But it gets much more definative
than that. In other words, two ground rods, 24 inches
apart, could have different grounding capabilites. There
are tests, using 'fairly' sophisticated equipment, that
measures the resistance of your ground rod to having
'perfect' contact with the earth ground.


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RE: Grounding a Phone Line

A proper system won't have a potential difference. This is why all the parts of the grounding electrode system need to be bonded together as well as certain other items.

It is NOT an issue with loops as he theorizes (yes that is an issue with audio), Grounding systems aren't necessarily STARS.


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RE: Grounding a Phone Line

"I am a sound engineer and not a telephone specialist but... "

Sound is not the same as power, never has been, never will be.

Ground loops (even in audio) are only an issue in the presence of time varying magnetic fields (often produced bu other unbalanced signalling schemes).

The goal in power grounds is to provide as low a potential difference between multiple electrodes, and provide adequate earth contact for lightning transients and high voltage primary leakage in pole transformers.

It is NOT to provide a low impedance path for 120 V (the earth is way to high an impedance at this low a voltage).
See the now banned 'Worm Getter.'

It is for the 7,200 volt leakage from primary to secondary inherent in pole transformers, and any lightning that couples to the lines.

If you have widely separated ground rods (separate structures) the displacement current from charged clouds moving above can be significant and produce high voltages if the rods are not bonded well.

When a charged cloud moves through the air, an equal charge is below it and moving through the earth.


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RE: Grounding a Phone Line

I had a service upgrade done 3 years ago, and the electrician mounted a grounding block aside the panel for that specific purpose. Made the SatTV guy's day.


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RE: Grounding a Phone Line

Assuming you can't get the phone guy to do the ground rod, then you may as well get a proper ground rod for your electrical, and then bond it to the tel demarc box and the water pipe. I don't know if the wire's supposed to be a continuous piece between panel, rod and water pipe.

Here in BC I've only seen one satellite person ground a dish, and I suspect he was a telephone tech too, which is probably why, they were all properly trained.

When we do media roughins, we never run a ground wire, which seems somewhat short-sighted, but we don't. I've queried this with the boss and I just do what I'm told, and the electrical inspectors almost NEVER come and check.

When I rough in my own satellite stuff, when I run the ground to it, can I run it down the (metal) siding and join it to the electrical ground, and if so, should it be insulated, and what gauge?

I'm assuming that sort of a ground should follow a short path, be straight as possible and not run through the structure (I could run it with the satellite cable, and fish it to meet the ground where it bonds to the water pipe, but I'm guessing that's a no-no.)


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