Grounding phone lines
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  1. #1
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    Default Grounding phone lines

    My house was built in 1949 the phone company tied ground leads to the iron water pipes under the house. We use the land line only for DSL, no phone service. I am replacing the iron pipe inside the house with pex.
    My question is what to do about the phone grounds? Can I just tie the existing grounds to the main service panel ground system. I replaced the ground rod years ago. Or should I use a new ground rod just for the phone lines. I am probably overthinking the issue. Lightening is not a issue here.
    I suppose the house electric system was not grounded when it was built. It had a service upgrade in the 1970's that probably is when they added a ground rod and breaker panel. On newer construction I would guess that the phone lines are just tied to the house ground wires?
    Bill D.

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    Hi Bill. I think you would be safe to tie it to the panel ground. Ground is ground. I don't think there would be any advantage at all to driving a dedicated ground for the telephone assuming the ground you have for the service panel is relatively close by. My phone ground wire goes to the driven panel ground.

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    This may seem kinda silly but my first call would have been to the phone company...

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    Not sure I would go along with that. The reason is if for some reason the connection from the service equipment to the ground stake is interrupted, the phone system could be at high voltage. I would take it back to the ground stake directly.

    I would check with the phone company for their requirements.

    Tom

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    The NEC requires the 'phone line' to be bonded to the power service grounding electrode 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 then be bonded to the building's power service grounding electrode.

    As with all things NEC, modifications are required to comply with the recent code revision.

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    Here for new residential construction the phone co wants a separate ground rod (not bonded to the utility ground) which they provide. They did mine last year. Call them.

    There is no ground on the phone system other than the protective sheath on the incoming cable. That is not extended beyond the telco demarcation point.

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    I know Home Depot used to sell these 6 to 8 foot copper rod, 3/4" thick. You pound them into the ground with a sledge hammer than pour brine or copper sulfate or whatever (electrolytic of your choice) into the ground around it. Then you can attach stuff directly to it or clamp a copper grounding strap to it and lead that into the basement. If you want, you can drive multiple rods into the ground and connect them all together.

    When Tesla grounded Wardenclyff Tower (https://en.wikipedia.org/wiki/Wardenclyffe_Tower) he drove 16 iron pipes 400 feet into the bedrock below. He was very big into grounding.

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    A good, dedicated ground will avoid a whole host of piddly problems with your phone line, even if you only use it for data. Regards, Clark

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    Even if lightning is not an issue there are still many things that can raise that DSL line to dangerous/damaging levels. A falling power line that contacts it is just one. In that case you are likely to have damage to computer equipment. Most surge protection shunts the excess voltage to ground (earth) and will not work without that connection.

    As others have said, contact your provider to see what is required in your area.

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    Whatever grounding is done will most likely be through some protective equipment. The standard "plain old telephone set" used a balanced line, neither side of which could be grounded without adding noise and problems.

    Ground it to the same thing as your service box. Plenty good, and that's how it is supposed to be done. Lightning rods also have to be connected to the service ground, although they may also have their own ground system.

    Yeah, you probably want something to open up if you get a power cross to the local 4160 Volt line.

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    DSL via phone line?
    I gotta ask how much that costs and your download speeds?

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    If yours is like the other phone companies they will want a separate ground. If you lose your neutral for any reason the power can feed back into the phone company ground which can differ in potential.
    This was especially necessary in or near a substation where we had a fancy optical system to float our ground in relation to theirs and special care was taken to keep the grounds isolated.

    Normally this is a 6 to 8 ft copper coated rod driven in the ground near the phone entrance to the house.
    Call the phone company and I'll bet they will send someone out to put one in, probably at no cost.

    Not going to get into grounding theory here but power ground is different than phone co ground.
    35 years as a telephone engineer.


    Quote Originally Posted by APD View Post
    DSL via phone line?
    I gotta ask how much that costs and your download speeds?
    Here's our prices
    https://www.mvdsl.com/bundles-phone-...sidential.html

    Keep in mind that with DSL you are the only one on that line. With wireless and other services you are sharing the bandwidth with others.

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    Quote Originally Posted by KIMFAB View Post
    If yours is like the other phone companies they will want a separate ground. If you lose your neutral for any reason the power can feed back into the phone company ground which can differ in potential.
    This was especially necessary in or near a substation where we had a fancy optical system to float our ground in relation to theirs and special care was taken to keep the grounds isolated.

    Normally this is a 6 to 8 ft copper coated rod driven in the ground near the phone entrance to the house.
    Call the phone company and I'll bet they will send someone out to put one in, probably at no cost.

    Not going to get into grounding theory here but power ground is different than phone co ground.
    35 years as a telephone engineer. ...
    The phone company ground here goes straight from the protection block to the service ground bonding wire a few feet from the pipe it grounds to. They piggy-backed a clamp on the service ground wire. Done via obviously original phone company wire, and known to be untouched over the last 30 years, despite installing DSL and later "U-verse" internet (phone is still a POTS).

    Protection block is a ceramic block, with the protector presumably in the central "knob". Possibly thyrite, maybe something else.

    During upgrades, service guys wired to the same old protection block.

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    Yep the only reason twisted-pair POTS lines are grounded these days is via an over-voltage
    protection (often a spark gap) that breaks down to clamp the lines to ground in the event
    of any induced voltage from an unwanted source like lightning or accidental contact with
    power lines.

    In the old days party lines would ring from one line or the other to ground (often with
    a polarized ring signal that premitted four numbers on one twiste pair) but those days
    are long long gone.

    There seems to be a theme here. All the old bell-heads stick with twised pair copper. Here
    as well it's DSL over a dry pair that comes in the house along with the POTS line.

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    Maybe I misread... but DSL uses the existing POTS line - no additional dry pair needed.

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    Quote Originally Posted by Lakeside53 View Post
    Maybe I misread... but DSL uses the existing POTS line - no additional dry pair needed.
    Yep, the DSL was connected to the same old wiring.

    The U-verse probably isn't, just because we have kept the POTS and don't have the locally powered U-verse phone. Wanted the phone to still work when the power is out for a week.

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    I had a second line installed way back when the Web was mostly dial-up. They put a Network Interface box on my house, with its own ground rod. Cost me nothing. I have not had a land line for about 20 years.

    George

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    Quote Originally Posted by JST View Post
    Whatever grounding is done will most likely be through some protective equipment. The standard "plain old telephone set" used a balanced line, neither side of which could be grounded without adding noise and problems.
    Well.. in legacy 2W copper systems the Telco ground didn't just protect the NTE - it also had a "Day Job" so to speak.

    "Ground Start" to draw dialtone.


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    If the grounds are NOT bonded, a nearby lightning strike can cause a BIG differential voltage between the telephone and service grounds that can damage equipment or both perhaps start a fire. This happened to someone I know. The phone company bought him a lot of replacement gear.

    Think of a target with the strike at the bulls-eye. That's the point of maximum voltage. Every ring farther from the bulls-eye has a progressively lower voltage. Ground rods at different radial distances from a strike will have a voltage between them. If the strike happens perfectly in line with the two rods that can be a pretty big voltage. (The voltage at the strike point can be tens of MV. That's Megavolts.)

    We're not talking big differences in distance between the ground points here to make a real difference. Grazing cattle facing directly toward or away from a nearby strike do not survive at distances where their herd members that are side-on survive, because the end-on cattle have a bigger differential voltage between their fore and hind legs than the side-on cattle do between their right and left legs. The voltage gradient is really big anywhere near a strike.

    John

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    "Maybe I misread... but DSL uses the existing POTS line - no additional dry pair needed. "

    That's the way it was originally for me but the ISP for some reason wanted to change to a
    dry pair.


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