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"RJ45" crimp connector flavors

Discussion in 'Electronic Design' started by Don Y, Dec 9, 2013.

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  1. Don Y

    Don Y Guest

    Hi,

    I've asked this in several places (possibly even here,
    previously) and still haven't received a good answer...

    RJ45 (8P8C) connectors come in a variety of styles, chiefly
    cable type (flat vs round) and conductor type (solid vs
    stranded).

    The former distinction is relatively easy to recognize. But,
    the latter doesn't seem to be consistently recognizable!
    (yes, I've seen the Wikipedia page).

    Almost all of the connectors that I have *appear* (see above)
    to be for stranded wire -- despite coming out of bags marked
    "for solid wire"!

    OK, it's possible that the bags got mismarked at the factory
    (though I have examples of such from different vendors!).
    But, I wonder if it isn't just a "manufacturing economy"?
    I.e., if one type (e.g., stranded) worked equally well for
    the *other* type (e.g., solid), then I could see manufacturers
    making a single product (perhaps a *hybrid*) and packaging it
    as *both*!

    At least, that's the only reasonable explanation I can find
    for these observations...

    Can anyone shed any light on this? Or, *definitive* criteria
    that I can use to examine the IDC contacts of each connector
    for some subtle clues?? (I imagine I can dissolve the plastic
    body if necessary to ensure full access to an unmolested
    "pin")

    Thx,
    --don
     
  2. Baron

    Baron Guest

    Hi Don,

    The contacts can be pulled out of the connector to be examined. If you
    look at the teeth on one type there are three barbs slightly offset
    from the centre line, on the other there are only two barbs that are in
    line. I belive one type can be used on both soild and stranded cables
    the other only on stranded. As far as I am aware these are the only
    variations between the two.

    YMMV.

    Regards:
    Baron.
     
  3. Don Y

    Don Y Guest

    Hi Baron,

    Really? Man, you've got *much* better eyes than *I*! I can't
    even see what to grab *onto*! :<

    OK, I'll believe you and drag one under the stereoscope and see
    if I can figure out how to coax it out of the plastic (I know
    it can be pushed *into* the plastic body further than it's
    "rest" position -- by the crimping action)
    So, presumably, the ones I *appear* to have (I am assuming that,
    on closer inspection, they will prove to be *truly* identical
    and not hiding some detail that is not apparent to the unaided eye)
    would be the ones that work with both types?
    OK. I will have to check. Looking at them "side on" doesn't
    shed much insight on what they are really like. (e.g., hard
    to tell if there are two -- or more -- barbs and whether they
    are inline or staggered.)

    [Perhaps I can find a detailed mechanical drawing at somebody's
    manufacturer web site...]

    Thx!
    --don
     
  4. Don Y

    Don Y Guest

    Hi Jeff,

    Ah! This contradicts (to an extent) the description on the
    Wikipedia page I mentioned. E.g., the connectors I have appear
    to be the leftmost in the photo claiming to be "solid or stranded".
    Note the Wikipedia page suggests this is "stranded" (only).
    At 30X under the stereomicroscope, you can't see anything more
    than what is visible to the naked eye.

    The top "wire side" of the connections is obscured by the bulk
    of the latching tab. Even made from "transparent plastic" it
    still proves to be effectively opaque by the time you get "down"
    to the contacts. (though I can see all the tooling marks
    from the injection mold in which the shells were cast!)

    The bottom "contact side" of the connector shows nothing but the
    exposed contact that mates with the female counterpart. Peering
    up *into* the connector body from below doesn't yield any image
    for the same reason as peering from above.

    The *side* of the connector only exposes the contact in profile.
    And, despite the "depth" that the stereomicroscope affords, the
    difference in the "planes" of the two "teeth" is just not
    apparent. Any seeming difference can just as easily be
    attributable to my holding the connector body at a tiny angle, etc.

    (looking into the connector from the front or back are equally
    pointless -- too much "in the way")

    A USB microscope nor "decent glasses" won't change those observations!

    I am still at a loss as to how to *extract* the contact given how
    closely spaced they are. Perhaps a *pin* digging into the metalic
    portion might allow enough force to be exerted to wiggle it free?
    Though they don't *feel* that willing to move...
    Thanks, but I know how to make reliable CAT5 cables. :>

    Also, be aware that some connector shells allow the wires
    to be pulled *through* the connector body and out the
    other side -- then, trimmed flush with side cutters.

    (I'm not a fan of this -- "traditionalist"? -- though it would
    make verifying actual wire order a LOT easier!)

    And, the apparent answer to my query is: some connector shells
    support *either* solid or stranded (which explains why there is
    no difference in the "bags" of connectors that I have here!)
     
  5. Don Y

    Don Y Guest

    Hi Jeff,

    Then the Wikipedia description is inaccurate (or, at best, misleading)
    As I said, I can clearly see two prongs with my unaided eyes.
    But, I can't tell if there is a *third* prong. Nor if the
    two prongs are coplanar. I can see a difference in depth but
    can't attest that this isn't attributed to my position of the
    connector body itself.

    And, given that there are two bags with different part numbers
    (solid vs stranded), one would *think* there would be a noticeable
    difference between the connectors ("Which bag did these fall out
    of?")
    As I said, I can see the two teeth to be at different depths
    from the objective. But, is that because the connector body
    is skewed? The contacts not truly parallel to the edge of
    the body? etc. There's very little difference between the
    tips of the two teeth if there *is* any!
    No, we're talking about a *bare* connector. No wires inside (how would
    you see around the wire if it was present?). When building a cable,
    I can see/verify the ends of the wire are fully inserted with my unaided
    eyes. That's how I tell if I may have been "off" when trimming the
    conductors to the same "penetration".
    I'm going to try to pry it out with a small stainless steel pin.
    There's a bit of a gap on each side of the "blade" so if I can
    get it to wiggle, it will probably fall out (and get lost in the
    carpet pile)
    No, I just use a Navitek. IME, cable failures are pretty apparent
    while you're making them:
    - soft crimp (you know before the crimp is done that it "missed")
    - misplaced white (one of the whites shifted as you were inserting)

    The first you just learn from instinct -- it just *feels* wrong!
    No need to check, it's bad. Cut off the connector and try again.

    The second turns up in a cable test.
    Seeing white is easy. Seeing whether it has a green or blue tracer
    is the tricky part!
    I don't hire folks for that sort of thing. I don't *do* that
    sort of thing, either! I only deal with short cables that I
    need to be "the right length" and can't rely on store-bought.
    There's no reason to *buy* connectors when you've got *boxes* of them
    already! :>

    I'll pull one out of each "type". Use unopened bags just to remove
    all doubt. If the contacts appear the same, then it will be as I
    initially speculated:

    "...I could see manufacturers making a single product (perhaps a
    *hybrid*) and packaging it as *both*!"
     
  6. Jasen Betts

    Jasen Betts Guest

    connectors made for solid will have teeth tips offset from the
    centreline
    It should be reasonably easy to pull the contact out of an uncrimped
    plug, crimped plugs need a little more effort but the contact can
    usually be lifted using a tool with a sharp point.
     
  7. Don Y

    Don Y Guest

    Hi Jeff,

    I can see *that* much detail with my unaided eye! What I can't
    *reliably* discern is whether the two prongs exist in the same
    plane, staggered planes or at entirely different angles to
    each other (e.g., "twisted").

    Recall, I'm comparing two connectors that *claimed* to be
    different (prior to this thread) and trying to understand what
    that difference could be (ans: none!). Since they both appear
    the same (two prongs) when viewed from this "side view", the
    difference "*must*" have something to do with the spacing of
    the prongs, right?

    (Reiterating: they were *supposed* to be different...)
    I was thinking the third prong (middle) would be in a different
    plane than the other "end" two. Farther "into" the screen.
    Unless, for stranded wire, they were trying to pick up different
    places in the "twist".

    (Reiterating: they were *supposed* to be different...)
    In my case, just a large box full of little bags (probably 100
    pieces in a bag?). The "sorting" involved reading which bags said
    "round" vs "flat", or "solid" vs. "stranded". This latter
    distinction now appears to have been artificial.
    No, depth when viewed from the side -- as in your photos.
    Put the connector on its side. Then, gauge the distance
    "into the screen" of each of the tips.

    Now, decide if the difference is because the metal is
    actually bent to ensure the tips are in slightly different
    planes (one wire thickness); or because the contact isn't
    actually perfectly parallel to the outer surface of the connector
    as it sits on the microscope's stage; or because there is a
    taper/imperfection in the shape of the connector shell as
    it sits on the stage.

    If, instead, I could have rotated the connector into its normal
    orientation (pins down, locking tab up), AND observed the
    teeth from above, it would be easier to use the length of the
    contact as a straightedge and determine if the teeth were
    collinear or staggered. But, doing so means trying to peer
    *through* the locking tab.
    I can see it. I just can't claim that it is an intentional
    feature or a "manufacturing/viewing tolerance"
    Oh. I don't have a problem seeing the wire placement while the
    connector is in the crimper. Usually, screwups are obvious
    before I even get the connector shell into the crimper
    (wires into shell, inspect, connector into crimper, verify,
    crimp)
    In this case, I'm stringing new cables under my worktables.
    I need 16 *different* lengths from 5 to ~30 ft (to cut down on
    excess "service loops" that add to the clutter).

    I'll have to do a similar task in the "computer lab" I've been
    setting up, tomorrow. My back will not be happy crawling around
    on the floor tacking cables *up* to the underside of the tables!
     
  8. Crimp stranded wire in. If the prongs go through the center of the
    wire, it's stranded only.

    Crimp solid wire in. If it's very hard to crimp or the wire snaps off,
    it's stranded only.


    The bigger problem I've seen is that you never know what gauge of wire
    the no-name jacks are for.
     
  9. Jasen Betts

    Jasen Betts Guest

    many stranded plugs don't work well on solid wire, gining intermittent
    connections.
    Some use double ended inserts and fit plugs to the fixed wire.
    (I use punchdown blocks for the fixed wiring)
    There is lots of solid cat6 made, I would not be surprised if most of
    it is solid.

    The suplier we at work (and much of NZ it seems) buy it off has 1662
    "rolls" of solid and 277 of stranded. or 502km solid and 78km stranded
    rolls are mostly 305m but some 500m and some as short as 50m

    (I pasted their website into a spreadsheet)

    they also stock cat6 patch cables, 99761 pieces or 241km. (all stranded)

    If their stock levels are representative there is (by length) twice as much
    solid made as there is stranded.
     
  10. Don Y

    Don Y Guest

    Hi Jeff,

    Not an issue -- I can tell round from flat. :> Above, I was referring
    to the fact that there doesn't appear to be a real distinction FOR
    THESE PARTICULAR "solid" AND "stranded" connectors. They apparently
    use a "pin" that is equally applicable (so, the part numbers on the
    bags are artificial)
    And *I* should probably eat *something*, today! :-/
     
  11. Robert Baer

    Robert Baer Guest

    Connectors that are eXplicitly made for solid wire have a slotted
    fork; the wire goes into the slot which has knife-like edges to displace
    some of the copper and make a cold weld connection,which is very reliable.
    Use of stranded wire is rather counter-productive,to say the least.
    The strands get pushed around and the connection not as robust, and can
    be poor.
    The IDC scheme does seem to work, tho . . refer to common use in flat
    computer cables as one example.
     
  12. Don Y

    Don Y Guest

    Hi Jasen,

    <frown> It's also possible that more stranded is *sold* and the
    (relatively) "large inventory" of solid is just "old stock" that
    has been sitting around (no demand). You'd have to watch the
    inventory over time to get a better feel.

    <shrug> Dunno.
     
  13. Don Y

    Don Y Guest

    Hi Doug,

    But that says nothing of the relative amounts of solid vs stranded
    sold, "in general".
    --------^^^^^^^^^^^^^^^^^^^^

    Except for those who feed cable manufacturers -- who will probably
    see *zero* (relatively speaking) solid wire purchases.
    Agreed.

    OTOH, how many patch cords get discarded over time? Broken latch?
    Knotted? etc. In that same time period, have you ever seen
    someone *pull* the wire that's in the walls out and replace it?

    E.g., I'm just coming to the end of my fourth? (or fifth?) box
    of cable for the house. I *know* none of it will ever be replaced
    because it won't be accessible (no attic or basement). Yet I
    probably toss a "patch cord" every couple of weeks. Over the course
    of a home's lifetime, how many feet of "stranded" does that
    represent?

    [Note, in my case, many drops never see a patch cord on the "far end"
    as they are hardwired to "devices". I don't think that is common for
    most installations where you'd tend to have patch cords on each end
    of the infrastructure wiring: from servers/switches to "distribution"
    and from end drops to "end devices". Plus, stranded wiring within the
    data center itself.]

    It would be interesting to see total solid vs stranded production
    (consumption) "industry wide".
     
  14. Jasen Betts

    Jasen Betts Guest

    yeah, I've seen 25 pair "key system" wiring pulled and replaced with cat5
     
  15. What is "this application"?

    Infrastructure wiring (more-or-less permanent stuff inside walls and
    whatnot) is pretty much always solid.
    Don't be silly. Most cat 6 cable is solid. Check the 1000ft spools
    at any cable wholesaler. The only thing stranded is used for is patch
    cables that get moved around a lot.
    Yes, the crimp connectors are different. Some crimp connectors are
    designed for use only with only, some for solid only, some for either.

    I've once tried (unknowingly) using standed-only connectors on solid
    conductors. They don't work reliably in the long term.
    You're over-simplifying. The design of the end of pin where it pushes
    through the insulation differs.
     
  16. Don Y

    Don Y Guest

    Hi Jasen,

    But that's "replacing (with something different)" not replacing due to wear.

    Here (US) "abandoned cable" is supposed to be removed -- unless clearly
    tagged "for future expansion"
     
  17. Jasen Betts

    Jasen Betts Guest

    So you don't expect your house to last longer than cat6 is viable?

    I bet the person who commisioned the key system thought that was a
    permanent solution, someoned later replace it wuth a panasonic
    digital/analogue PABX (using fewer pairs on the same copper), we
    replaced that with asterisk and SIP phones on CAT5e.
     
  18. Don Y

    Don Y Guest

    Hi Jasen,

    *This* house is a bad example. I am *sure* the cable will be
    here when the house ultimately collapses, is bulldozed for a
    new development, etc. It is just not practical to *remove*
    the wiring: no basement, no attic. To get the wires *out*,
    you'll have to rip open the ceilings, walls, etc. "Ain't gonna
    happen" :>
    How long was the cabling there? How many feet of "patch cords"
    connecting that CAT5e infrastructure wiring to SIP handsets,
    network switches, etc. will be replaced in the time that the
    wiring stays *in* the walls? (i.e., assuming it *is* eventually
    removed to run fibre, etc.).

    Most folks do not repair "patch cords". Break a tab/latch and
    the cord ends up in the trash bin -- even if you delay putting it
    there, you *know* that's where its ultimately headed. I've tossed
    two 50' cables in the past month because the tabs snapped off.
    Try to replace? Or, buy another for $20? (in a business environment,
    this is a non-decision -- *take* another from the *stock* of cables
    you prepurchased for this reason!)

    [The folks most likely willing to repair the cable to save the $20
    probably haven't invested in the tools and parts to do so]

    OTOH, in the unlikely event that someone mangles a *jack*, you
    won't pull all the associated cable out of the wall and start
    fresh. Instead, you'll replace the jack allowing all but an
    inch or two of said cable to remain in place. So, the "solid"
    remains in use while the "stranded" gets replaced.
     
  19. Jasen Betts

    Jasen Betts Guest

    at-least 6 months, before that I can only speculate.
    key systems out out of fashion in the early 1980s,
    so, more than 20 years. The sockets and termination blocks
    were on MDF plaques so less than 35 years.

    none, you picked another bad example. the buliding was demolished
    after the Feb 2011 earthquake,
    I often re-use the end with the good plug for a purpose
    that would have otherwise required fitting a plug or cutting
    up a good cable.
    We pay a bit over half that for 15m cables..
    I have not seen a high rate of damage to patch cables. we buy one
    of the types with snag resistant tabs and run them away from crush
    risks, but mainly we leave them alone. treated properly they last
    almost forever.
     
  20. Peter

    Peter Guest

    I have recently had to deal with this issue at work.

    We have found that a lot of RJ45s are not reliably crimped. Maybe a 5%
    failure rate.

    These are Chinese-made cables which we buy in, custom made, 1000+.

    It appears they were *adequately* crimped i.e. the compression tool
    did penetrate far enough.

    So what happened?

    Probably they didn't use the correct wire size for the contacts.

    There is a separate issue which is that a second crimp is used to hold
    the cable insulation in place, as a form of strain relief. This also
    need the correct cable diameter to be used, otherwise you get an
    unreliable connector.
     
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