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Thread: Distance of Telephone (POTS) wring?

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    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    Default Distance of Telephone (POTS) wring?

    Anyone know what the maximum distance is for telephone wiring? I need to extend telephone service about 3000 (yes, three thousand) feet. I may use fiber, but I need to cost it out both ways.

    Thanks,
    Jason

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    In the Trades brownizs's Avatar
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    Why would you use Fiber? POTS has to use Copper. Now if you are talking about Networking, then you are looking at a completely new subject.

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    Like an engineer alternety's Avatar
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    Do you perchance have any rolls of cat 6 lying about? If so, try testing with that. Google of a line extender bidirectional amp. Fiber gets expensive for the conversion devices.

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    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    You'd be surprised how far you can extend POTS wiring. The main problem might be EMF problems -- lightning, etc. The only hard number I know of offhand is a 5000' limit for an analog line on a Cisco VG248 -- an analog-to-digital voice gateway -- which I would guess would be a good guideline. All in all, I'd say 3000' would work, but fiber would be very cool.

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    Plumber jimbo's Avatar
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    Distances up to 15000 feet from a central office are not uncommon for POTS. Depending, adding 3000 feet to yours probably won't be an issue.

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    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    Quote Originally Posted by brownizs View Post
    Why would you use Fiber? POTS has to use Copper. Now if you are talking about Networking, then you are looking at a completely new subject.
    Because fiber is immune to electromagnetic interference. There are some Cu to FO converters available for POTS.

    Quote Originally Posted by alternety View Post
    Do you perchance have any rolls of cat 6 lying about? If so, try testing with that. Google of a line extender bidirectional amp. Fiber gets expensive for the conversion devices.
    I don't have any rolls of Cat6. Most of designs are on paper only. I'll check into this line extender bidirectional amp though.

    Quote Originally Posted by Mikey View Post
    You'd be surprised how far you can extend POTS wiring. The main problem might be EMF problems -- lightning, etc. The only hard number I know of offhand is a 5000' limit for an analog line on a Cisco VG248 -- an analog-to-digital voice gateway -- which I would guess would be a good guideline. All in all, I'd say 3000' would work, but fiber would be very cool.
    I think that I saw a post regarding that Mikey... but like the next poster said, it could be many thousands of feet prior to that too. I would run the cable (probably CAT6) in rigid metalic conduit.

    Quote Originally Posted by jimbo View Post
    Distances up to 15000 feet from a central office are not uncommon for POTS. Depending, adding 3000 feet to yours probably won't be an issue.
    Maybe I'll call the Teleco. They can probably tell me my distance.

    Thanks!
    Jason

  7. #7

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    Unless you are way out in the country adding another 0.6 mile should not be a problem for POTS, although if you have DSL on the line it may stop working if you are already at 15000 ft. DSL has a max range of ~18000 ft. and sometimes less depending on the age of the DSLAM equipment.

    Your TelCo should be able to tell you how far you are now. Easiest to call repair (ususally 611) and ask them.

    My biggest concern would be lighting if you run extension as overhead rather than burried.

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    Computer Programmer Bill Arden's Avatar
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    There can be a problem if there are two phones "in use" at the same time at both ends.

    In other words extending the line 3000 feet is ok, but adding an extension 3000 feet away and then picking up phones in both locations will cause one phone to be hard to hear.

    Edit: clarification.

    A possible senerio

    1. Telco
    2. building one, phone 1
    3. 3000 foot extension
    4. Building two, phone 2

    In this configuration the line to phone 2 is not terminated when phone 2 is not in use.
    This could cause problems when using phone 1.

    Phone 2 will work fine as long as phone 1 is not in use.
    Last edited by Bill Arden; 03-10-2008 at 09:24 PM.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

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    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    Default POTS-Fiber converter

    Here's one solution, under $300 per end, good for up to 3 miles. This would solve EMI and lightning problems, and I think would address echo and termination issues as well (and very cool ):
    http://www.techforless.com/cgi-bin/t.../SAPTF3311-100

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    Moderator & Master Plumber hj's Avatar
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    Default phone

    He didn't say whether this was an extension phone, or it could be that the building is 3,000' from the phone company's connection box.

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    Plumber jimbo's Avatar
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    This whole discussion brings back long faded memories. My grandfather, and his two brothers, between them retired from AT&T with 100 years service. They were written up in the company magazine Long Lines back in the thirties. They were long distance linemen, involved in building the first transcontinental telephone line in the early part of the 20th century. They had to string the lines, and also "balance" the lines with components to maximize distance, eliminate "ringing" and echos. Grandpa Duggan also packed a pistol! because he was the Foreman and carried the crew payroll with him as they traveled for weeks at a time out in the boondocks! Those were the days! Of course they would roll over in their graves at the state of the company today!

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    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    Quote Originally Posted by OscarG View Post
    Unless you are way out in the country adding another 0.6 mile should not be a problem for POTS, although if you have DSL on the line it may stop working if you are already at 15000 ft. DSL has a max range of ~18000 ft. and sometimes less depending on the age of the DSLAM equipment.

    Your TelCo should be able to tell you how far you are now. Easiest to call repair (ususally 611) and ask them.

    My biggest concern would be lighting if you run extension as overhead rather than burried.
    Yup! We're way out in the country here! It will be buried, not aerial.

    Quote Originally Posted by hj View Post
    He didn't say whether this was an extension phone, or it could be that the building is 3,000' from the phone company's connection box.
    It's the latter.

    I've been thinking about the situation and I can probably just have the teleco relocate the service on the property and get by with 750 feet.

    I did see POTS to Fiber converters....although that $300 is a lot less than what I found them for earlier. Thanks!

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    Computer Systems Engineer jdoll42's Avatar
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    One other thing to watch out for is common grounding problems. Evidently two buildings that are both grounded might actually have a different voltage potential between the different grounds. I know it sounds odd, but they drilled that into my head when I took a bunch of different Cisco networking classes. I'm no electrical expert, but I'm sure some of the guys (and gals) around here could elaborate on that topic.

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    I&C Engineer (mostly WWTP) Lakee911's Avatar
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    Quote Originally Posted by jdoll42 View Post
    One other thing to watch out for is common grounding problems. Evidently two buildings that are both grounded might actually have a different voltage potential between the different grounds. I know it sounds odd, but they drilled that into my head when I took a bunch of different Cisco networking classes. I'm no electrical expert, but I'm sure some of the guys (and gals) around here could elaborate on that topic.
    That is possible. Theoretically, if both buildings are grounded properly, even if fed from different voltage sources this can't happen. In actuallity though, it could and does.

    Thanks.

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