What things will cause CAT5 interference?

Posted on 2009-04-16
Last Modified: 2013-11-09
I need to run a 50' CAT5 cable between 2 bldgs and since I'm doing it myself I need some help to know were NOT to run it and due to limited space in areas a conduit is not an option. How close to flourscent lights? How close to electric cables, etc?
Question by:murphymail
    LVL 27

    Accepted Solution

    If you're running between buildings, you should NOT do it.  You should run fiber between buildings - or use wireless.  Copper between buildings introduces risk to your network and building for lightning strikes and issues with grounding differential between buildings.

    To answer your question inside, generally, Cat5&6 unshielded twisted pair does not require conduit, unless local building and electrical codes dictate it.  You should stay at least 12 inches from florescent lights, and I would try to stay 6" from high voltage - unless it's in conduit.  Generally, it's best to stay away from it, support your cables independently, and if you must cross high voltage, do so at 90 degree angles.  You especially want to avoid running cablng in parallel to other cabling which can interfere (high voltage).

    Hope this helps.


    Author Comment

    What about alarm systems and their cabling? Anything else to look for to stay away from? thanks.
    LVL 27

    Expert Comment

    Alarms are low voltage. Ok.
    LVL 11

    Expert Comment

    Are the two buildings structually attached in any way, like a covered walkway, common metal water pipes ect..? Are they electrically connected? If so, considering that they are less than 50' apart, the potential difference between the two buildings will be near zero. If the cable is properly buried and protected at each entry point, then lightning worries will be no more than having a broadband internet device plugged into your network. Remember, cable and DSL are run for miles on exposed poles before getting to an end user.
         I would have no worries running twisted pair cable rated for direct burial between two buildings 50 ft apart, especially if they are structually connected. However, as pseudocyber stated, my first choice would be fiber if money allowed. I would not run UTP cable in an aerial situation (For ethernet use) between two buildings unless it is under a covered walkway roof or similar situation where it is somewhat protected.
         Most alarm system wiring will be running low voltage 12 to 24 volts DC or AC. I wouldn't want to run parallel with them for a long distance but they shouldn't cause any worries. If you must run parallel with them, I like staying at least 6" away as pseudocyber does.

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