Conduit size for phone, cable, etc.

Discussion in 'Electrical Forum discussion & Blog' started by jadnashua, Mar 23, 2011.

  1. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,316
    Location:
    New England
    I live in a townhouse condominium. This summer, we are going to repave the parking area. Our original phone, cable, low-voltage type stuff was installed through the buildings in the basement ceiling during construction. As times have moved on, it would be nice to maybe upgrade the wiring, but going through 10 units to get to the other end is just not going to happen.

    So, I'm suggesting that we install some conduit under the pavement when we tear things up to regrade and then repave. It sounds like we'd need to run individual runs for each unit. The longest would end up at about 200'. To enable say RG6, or a phone line, or maybe a fiber optic cable to be fished through the thing, what would be the recommended size? Would it make sense to try to blow a pull string through each, or just wait until it needed to be used.

    They've installed fiber optic on the road, but won't bring it into the complex since there's no easy way to get it to individual townhomes. Plus, the old cable coax is just that, getting old, and mostly RG59, where RG6 works better.

    Thoughts on what would work underground, size, material?
  2. Jeff1

    Jeff1 New Member

    Messages:
    102
    Location:
    So Cal
    When I had a new phone line installed, the phone company made me use 1" conduit. They also told me where to begin and end.
  3. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    Individual pre-terminated fiber optic will require a minimum of 1-1/4 conduit and 1-1/2 is better. If your building has an equipment room in the basement then it is more likely the communications company would run a multi-strand FO cable and do on-site terminations in the equipment room.

    Ten individual coaxial (cable television) cables could be run together in a 1-1/2 conduit but the CATV company may prefer a 2 inch conduit or larger. They may also prefer to run a single cable and install a distribution amplifier in the basement equipment room.

    Generally speaking, PVC conduit is preferable for underground use. Your best answer will be to contact the various serving utilities (CATV, telephone, etc) and ask what they require for such services.
  4. SacCity

    SacCity In the Trades

    Messages:
    189
    Location:
    Sacramento, CA
    In wiring my apartments I've always used 1" conduit and frequently wish I had more room.
    In the exterior I would recommend 1-1/2" also use long sweeps.

    And yes always pull a string through.

    Also if you are going to run power through I would recommend a second conduit. Low frequency won't effect signals much but feedback on fluorescents can have an effect. Generally try and keep power and signal about 1 foot apart and when they cross do so at close to 90 degree angles.
    Michael
    Last edited by a moderator: Apr 6, 2011
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,316
    Location:
    New England
    There would be no intent of running power through this, only things like cable, or phone (wire or FO). There is no common equipment room, as I mentioned, these are townhouses, connected one to the other. So, running anything through the building would require getting everyone else to open up their unit, which just isn't going to happen, thus the individual conduits to a common area outside where the phone and cable stuff now is fed, and, when needed for say a cable or phone upgrade, they'd be able to run a new line. Several people have had trouble with their old lines, and been unable to support things like DSL or cable on the old runs, and had to go with alternative connections. We just want to be able to supply the new connections without tearing up 10 units' finished ceilings and gaining access, which is nearly impossible to get everyone lined up to do the work. A dedicated conduit per unit is more reasonable...just want it to actually be worthwhile, and not a waste of time.
  6. jwelectric

    jwelectric Electrical Contractor/Instructor

    Messages:
    2,565
    Location:
    North Carolina
    I would suggest one run of 1 ½ or 2 inch PVC for each utility, one for the telephone and another for cable.
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