LAN between two buildings

Discussion in 'Home Networking' started by Chris Laird, Jan 26, 2005.

  1. Chris Laird

    Chris Laird Guest

    A local business wants to extends an existing network from one Portakabin
    to another about 100 yards away.

    I briefly considered just running a long length of CAT5 between the two
    Portakabins but discounted this because of worries about damp getting into
    the cable or what a lightning strike might do the equipment or anyone
    unlucky enough to be next to it at the time.

    I also thought about fibre but I don't know much about it and the cost
    would probably be too high.

    So I think that leaves me with two possible solutions:

    1. power line networking (but I'm not really sure if this would work
    between buildings)

    2. wireless networking

    Without much experience of wi-fi kit, can anyone tell me if I had a 54g
    access point in each Portakabin would they see a strong enough signal to
    talk to each other over 100 yards of relatively open ground?
    Chris Laird, Jan 26, 2005
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  2. Chris Laird

    themanwhocan Guest

    Hi Chris

    They would probable see each other over that distance but I doubt you would
    get 54mbps. External hi gain antennas are relatively cheap nowdays though,
    so I would consider that option.

    themanwhocan, Jan 26, 2005
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  3. Chris Laird

    Paul D.Smith Guest

    Do they own the ground? Cat5e external grade cable is about £130.00 for
    305m from companies such as Videk No
    association, I just get their catalogues. You should be able to string it,
    or lay conduit and bury is without much bother I would imagine.

    Paul DS.
    Paul D.Smith, Jan 26, 2005
  4. Chris Laird

    Jim Howes Guest

    Damp isn't a problem if you use the right cable, and provide proper
    ducting. It's far more likely to get pranged, caught by vehicles, eaten
    by birds, etc.

    As for lightning, you can get surge protection with RJ45 ports, such as
    Belkin's F9G726uk3M-GRY, which provides 7 surge protected mains outlets,
    telephone, RJ45 connectors, 6000V, 90kA protection, unlimited
    connected-equipment-warranty, plus data recovery warranty.
    451-5736 £49.98 at RS

    Alternatively, there's 451-5708, cheaper at £34.99, with 6 mains,
    telephone and RJ45 connectors, 6000V, 45kA, £100,000 connected equipment
    warranty, for £34.99
    Fibre is expensive, and requires some funky tooling to do it right
    (although in many cases you can do it wrong and it will still work..)
    Problem here is if it does work, it would probably work between your two
    buildings and several other buildings too.
    External antennae would be ideal, depending on your portacabin's
    structure. You may be able to get away with sticking them on
    windowsills, etc. You also need _RADIO_ line of sight. This is utterly
    different to normal line of sight, and is rather difficult to explain
    without going into fresnel zones and so forth. To summarise, think of a
    rugby ball or US Football, with the two pointy ends being your two
    antennae. The rest of the ball is the area you need to keep clear of
    radio obstacles (the occasional tree branch is ok, but anything more
    substantial, and you will have so much fun[1] trying to get it to work

    If you don't have much clearance, you can narrow the signal path by
    using things like yagi antennae.

    If, on the other hand, you are at two ends of a field, with nothing in
    between, then you'll probably find that the supplied antennae work fine.
    Mucking about with high gain directional antennae is rarely required in
    such cases.

    So, I think you'd be better off with ducted cat5, with surge protection
    and a switch at both ends. Far cheaper than a lot of other options.


    [1] This is possibly a strage usage of the word 'fun' that you
    previously hadn't experienced.
    Jim Howes, Jan 26, 2005
  5. Chris Laird

    RichGK Guest

    100 Yards is the very maximum distance for CAT5 ethernet, for a full
    capacity network you'd need a repeater half way, unless running at the lower
    10Mbps is acceptable. Our PCs that operate at 100 yards are problematic!
    I would have though so.
    RichGK, Jan 26, 2005
  6. Chris Laird

    stephen Guest

    then you have a wiring problem. 100m is the worst case limit for Cat 5, and
    allows for marginal cable, not so good installation, worst case inducted
    noise and interference and worst case equipment plugged into it.

    1000s of building have runs that approach 100m and everything just works -
    which means that in practice there is a lot of slack built into the

    if you have a lot of problems i suggest you get someone in to test the
    cabling system, and if you have a warrated system, look at whether the
    guarantee will get it sorted for you.

    If the OP doesnt want to use Cat5 - then he could buy a pre terminated
    length of fibre and use that - but the connectors are delicate and dont like

    whichever cable type is used, you want it well away from children, vehicles
    and other common sources of destruction - buried in a pipe or duct is often
    stephen, Jan 27, 2005
  7. Chris Laird

    w_tom Guest

    As others have noted, environment (ie dampness) creates no
    problems if proper cable is selected. Also properly
    recommended is the plastic pipe option that makes future
    cabling possible. Still the cable must be rated for burial
    even if inside that pipe.

    100 meters should never be a problem for networking IF the
    terminating equipment is properly constructed and the wiring
    is proper. To meet the 100 meter requirement, terminating
    equipment is designed to exceed 100 meters.

    Advisable to consider cat 6 wire. From experience in new
    homes, the cat 6 wire is going to be necessary in the near
    future. Of make the pipes large enough (with intermediate
    access holes) so that Cat 6 wire can be installed later.

    No one mentioned this most critical point. Each end of that
    cable must enter the building at the buildings single point
    ground. That far building is a lightning rod for computers in
    this building. A lightning strike anywhere on that building
    could find earth ground, destructively, via computers in this
    building. To avoid this failure, earth each end of any
    interbuilding wire at each building's single point earth
    ground - either by hardwire connection (coax cable) or via
    surge protectors (ethernet, telephone, AC electric). This is
    how telcos have installed phone lines for generations - a
    principle that old and that necessary.

    Transient damage is often directly traceable to wire and
    earthing failures. This figure from an industry professional
    (a provider of surge protector products) demonstrates the most
    important part is not even sold by them - earth:

    Notice the surge entering the building on a buried phone
    line. Ethernet is same.

    Wireless across that distance will not provide the bandwidth
    without careful installation. It too can be done, but must
    learn and struggle with more than you realize, based upon
    information here.
    w_tom, Jan 28, 2005
  8. Chris Laird

    deKay Guest

    Soni tempori elseu romani yeof helsforo nisson ol sefini ill des Fri, 28 Jan
    2005 02:21:52 -0500, sefini jorgo geanyet des mani yeof do
    Gah! It is possible to mention lightning or surge protectors *without*
    summoning w_tom?!

    Does he search Google Groups every day for those magic words?

    deKay, Jan 28, 2005
  9. Chris Laird

    Tx2 Guest

    LOL! Just what i was thinking ...

    i imagine him to be dressed in an immaculately pressed blue boiler suit,
    with clipboard and pencil tucked, very specifically, under one arm.
    Tx2, Jan 28, 2005
  10. Chris Laird

    w_tom Guest

    Notice no one mentioned how cables are connected between
    buildings - as telcos have been doing for generations. Why
    did you not address this obvious discrepancy? If concepts
    were commonly understood, others would have raised this point
    two days ago. No one posted how signal wires between two
    buildings must be routed. And yet it is critical to avoid
    computer and network damage. Why did you not provide that
    information? Were you waiting for the OP to first suffer

    Why did you let a critical fact go unmentioned when clearly
    the OP requires that information up front and during his
    planning? That is the first question you should have asked
    because that is information the OP was asking for. I make no
    apologies for the fact that you failed to warn the OP of how
    to install a network cable between two buildings.
    w_tom, Jan 28, 2005
  11. Chris Laird

    deKay Guest

    Soni tempori elseu romani yeof helsforo nisson ol sefini ill des Fri, 28 Jan
    2005 10:21:28 -0500, sefini jorgo geanyet des mani yeof do
    What does that have to do with me or my post? How is it my fault if anything
    happens to the OP?

    deKay, Jan 28, 2005
  12. Chris Laird

    w_tom Guest

    So why are you posting nonsense that is not related to the
    OPs original request for information? The OP asked for
    information. The purpose of this thread is to provide answers
    to his question. Why are you repeatedly posting useless and
    irrelevant ideas? Why do you not help the OP solve his
    w_tom, Jan 28, 2005
  13. Chris Laird

    deKay Guest

    Soni tempori elseu romani yeof helsforo nisson ol sefini ill des Fri, 28 Jan
    2005 11:22:27 -0500, sefini jorgo geanyet des mani yeof do
    Because I don't know the answer. I contributed to the thread to find out how
    you find all these threads about lightning and surge protection across the
    many, many groups you do.

    And please don't top-post. It disrupts the flow of the conversation.

    deKay, Jan 28, 2005
  14. Chris Laird

    Mal Franks Guest

    and makes baby Jebus cry
    Mal Franks, Jan 28, 2005
  15. Chris Laird

    Ben White Guest

    At work we've used these guys for all sorts of lighting protection.
    They do cat5 protectors and you'll likely get a very informative
    installation manual with it.
    Ben White, Jan 29, 2005
  16. Chris Laird

    Chris Laird Guest

    Many thanks for all the replies. I've now been to see the site and talk to
    the people involved and the situation is this:

    They already intend to dig a trench to run from the original Portakabin to
    the new one to carry mains electrical cable. Their electrician has measured
    the distance: the portakabins are 90m apart and he thinks he'll need a 100m
    run of cable to leave enough to terminate at both ends.

    Once the trench has been dug it makes sense to run cable for the network as
    well rather than rely on wireless. They also need telephones in the new
    portakabin so I've pointed them in the direction of a local firm who
    install small-medium telephone systems and do voice & data cabling as well.
    Their plan is to run two lengths of external grade CAT6 between the
    portakabins, one for voice and the other for network. Lightning protection
    is apparently not an issue as the ducting carrying the cable will be 50cm
    below ground.

    Each portakabin will only have two or three PCs in so I don't think
    there'll be any bandwidth concerns with bridging the two ethernet
    "segments" with a single cable. The PCs will be connected to a file server,
    and via a router/ADSL to the wider Internet for email and occasional web

    Can anyone foresee any problems with this setup?
    Chris Laird, Feb 2, 2005
  17. Chris Laird

    w_tom Guest

    Lightning remains a major issue. Each building is a big
    lightning rod connected directly to computers and telephone
    switch in the other building via a buried line. However you
    are in the UK where surge damage is less frequent - probably
    one event in more than ten years. Therefore that contractor
    will not be around to accept blame.

    Two examples from industry professionals demonstrate how
    surges enter via buried wires. First, figure in this
    application note entitled "Need for Coordinated Protection"
    shows a destructive transient entering on buried phone wire:

    Second is this application note from an industry benchmark
    where distant lightning entered a (if I remember a German)
    communication building via buried wires:
    Third were many contractors whose computers suffered damage
    when connected to the Arienne rocket in S America. Lightning
    routinely damaged interface electronics via underground wires
    - until proper earthing was connected where underground wires
    entered the blockhouse.

    Proper grounding costs so little - almost nothing - when the
    wires are first installed. But costs to correct a bad
    installation are quite significant.

    Any wire that enters the building must first make an earth
    ground connection. Single point earthing. Before transistors
    existed, this was unnecessary. A direct strike to any
    building should result in no transistor damage - not one. But
    it means you install or enhance the single point ground;
    everything entering the building make a connection to that
    single point ground. You even have industry standard reasons
    why lightning protection has been required for 30 years.
    Apparently someone just hopes buried cables are not
    susceptible. Even BT is not that naive.
    w_tom, Feb 2, 2005
  18. Chris Laird

    no66y© Guest

    "Chris Laird" wrote in message
    My main concern would be quality of kit.

    good quality network cards, good quality cable etc should be fine @100m

    cheap crap cards and budget cable wont.

    it would be more cost effective in the long run to install good quality
    cable now rather than
    find problems in the future and have to get the shovel out!

    as I always say, you gets what you pays for.

    It all sounds obvious but you'd be surprised how many people are prepared to
    try and save 5p/m on cable
    only to find its crap and have the expense of starting again.

    Those who find they're touched by madness
    Sit down next to me

    Reply to address is a spam trap.
    Use no66y [at] breathe [dot] com
    no66y©, Feb 2, 2005
  19. Chris Laird

    Bernard Peek Guest

    In message <[email protected]>, Chris
    If I were managing this I would seriously consider putting in at least a
    spare CAT6 and possibly fibre too. It's cheaper to do that than to dig
    the trench up and replace the cables. Particularly after someone has put
    a new building over the top.
    Bernard Peek, Feb 3, 2005
  20. Chris Laird

    Lurch Guest

    Ever heard of ducts and rope? BT manage to use them the length and
    breadth of the UK, I'm sure the OP could manage 100m of it.
    Lurch, Feb 3, 2005
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