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Wireless Networks Thread, 50 μm and 62.5 μm Fiber in Technical; Hello all, Is there anyway of telling the difference between 50 μm and 62.5 μm fiber? I realise that 62.5 ...
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    Michael's Avatar
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    Question 50 μm and 62.5 μm Fiber

    Hello all,

    Is there anyway of telling the difference between 50 μm and 62.5 μm fiber? I realise that 62.5 μm is a lot more common, but it's recommended to use the same type throughout a network.

    What happens if say you have 62.5 μm in the walls, yet you use 50 μm from the fiber patch panel to a switch for example?

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    LosOjos's Avatar
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    To be honest, I would have thought the only difference it would make would be how efficiently it carries the signal, I remember reading somewhere that finer cable carries the signal better than thicker cable. I suppose that if you tried to pass the signal from a very thick cable (>150um) in to a finer cable (<80um) then you could have problems with signal loss, but a difference of 12.5um just seems insignificant... I have no experience to back that up though I'm afraid.

    More info here: Optical fiber - Wikipedia, the free encyclopedia (particularly here: File:Optical fiber types.svg - Wikipedia, the free encyclopedia)

    Just found this site that explains that passing smaller to larger is fine, but larger to smaller causes data loss: Power Penalty For Mixing 50/125 And 62.5/125 Fibers

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    Michael (5th April 2011)

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    Michael's Avatar
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    Thanks for that, much appreciated.

    I love this one liner: New TIA standards call for color coding cables and patch panels to prevent mixups.

    You don't say comes to mind as it's an absolute nightmare! The problem I have though is without knowing whether 50 μm or 62.5 μm is in the walls, what do I use to go from the fiber patch panel into the switch?

    At the moment 10/100 fiber media converters are used, however I want to change this and patch it in using an ST/LC cable into an SX transceiver operating at gigabit.

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    localzuk's Avatar
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    Quote Originally Posted by Michael View Post
    Thanks for that, much appreciated.

    I love this one liner: New TIA standards call for color coding cables and patch panels to prevent mixups.

    You don't say comes to mind as it's an absolute nightmare! The problem I have though is without knowing whether 50 μm or 62.5 μm is in the walls, what do I use to go from the fiber patch panel into the switch?

    At the moment 10/100 fiber media converters are used, however I want to change this and patch it in using an ST/LC cable into an SX transceiver operating at gigabit.
    Your existing patch leads should have details on them, failing that look at the sleeve of the fibre itself, it should have markings on it. I've yet to come across a fibre that couldn't be identified this way.

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    Michael (5th April 2011)

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    Most cables should have it written on it, if not might be worth looking up the spec of the exisiting media convertor, - it may only work with one type of cable, so you can fairly safely assume thats the type of cable being used.

    Steve

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    Michael (5th April 2011)

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    SYNACK's Avatar
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    Yes look at the outside of the cable. If you use different sized stuff for patch and run you get terrible loss and far more errors. 62.5 is the older standard and will happily handle 1GB/s, 50 micron is usually OM3 and can support 10GB.

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    Michael (5th April 2011)

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    Michael's Avatar
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    Thinking about it also, (worse case scenario), is I could go by the date of when the fiber was installed. When did 50 μm start to be available? I'm guessing 62.5 μm has been around for a good 15 years mainstream at least.

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    50/125 was invented in the 70's and started being commonly used in the 90's so that may not help.

    Steve

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    SYNACK's Avatar
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    Quote Originally Posted by Michael View Post
    Thinking about it also, (worse case scenario), is I could go by the date of when the fiber was installed. When did 50 μm start to be available? I'm guessing 62.5 μm has been around for a good 15 years mainstream at least.
    If it is older than 6-8 years old and uses multimode transcivers/modules then it is almost certainly 62.5 but the only way to be certain would be to get a look at the sheith, are their no accessable runs? Quite often there are bits that go through that wall mount capping stuff with a removable lid that you can pry off to get a better look then just click back on afterwards, it should also be on the current patch leads as above which is proably the easiest.

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    plexer's Avatar
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    Wall mount capping stuff = pvc trunking.

    Ben

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    Michael's Avatar
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    I will take a closer look later on in the week and report back. Thanks for all your help guys, much appreciated

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    SYNACK's Avatar
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    Quote Originally Posted by plexer View Post
    Wall mount capping stuff = pvc trunking.

    Ben
    Thanks for the translation, if we were talking in cisco language it is also called decorative wall mount but personally I do not find it overly decorative

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    Quote Originally Posted by Michael View Post
    What happens if say you have 62.5 μm in the walls, yet you use 50 μm from the fiber patch panel to a switch for example?
    62.5/125 vs. 50/125 Multimode Information

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    just to add to stevenewman's post:

    I have had this before and found a 62.5 micron fibre on quite a long run and then a 50 micron patch lead to connect to the switch and produced a huge ammount of loss. This would cause a noticeable reduction in performance ...

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    Check this previous thread, Determing Speed of Fibre

    You will find the link to my uploaded training manual.

    Mismatched patch leads will produce a 3db insertion loss (approximately half of the power available at that point)
    Anything greater than 6db in a given segment (between repeaters) will result in a blackout (the point at which the receiver is unable to distinguish between on/off or 0 and 1)
    Such losses are often mitigated by the use of Long Range Modules over short cable distances.

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