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  1. #14
    Join Date
    Apr 2011
    Location
    Pennsylvania
    Posts
    121

    Electrical tape

    Am I the only one who prefers to cut their electrical tape (usually with dikes) instead of ripping it? I'm a desk jockey, so maybe I'd do differently if I was an installer and had limited time, but I despise the wavy end of electrical tape that you get from ripping it....

    Good video. I like the idea of wrapping the drain wire back over the jacket.

  2. #15
    Join Date
    Jan 2008
    Location
    Near Philly
    Posts
    512
    Quote Originally Posted by osiyo View Post
    Nice training video.

    However, I always tell any new installer we get to NOT cut the jacket away as shown.

    If one is careful and does it right, it works 99.90% of the time. But I find that people are not always careful, nor do they take the time to closely inspect the conductor insulation to make sure they haven't accidentally nicked it. Especially considering that the installers are often pressed to be working as fast as possible; and also that they're often working in a spot of poor lighting, and cramped space.

    I find it better to tell them to cut off enough of the end of the jacket to get a grip on the pull string and then USE IT. Open the jacket enough to get the length of conductor exposed they need, plus a goodly bit, peel back the jacket and snip it off. Unravel shield back to where jacket was snipped and snip it off, along with pull string. When you've done the same with the next segment of cable, match em up then snip off the "extra" at the end you do not need. The idea here is that if you have nicked a conductor's insulation when you cut off that short bit of jacket so you could get at the pull string, that part goes bye-bye when you clip off the excess. I've seen many a time where we've had communications issues, sometimes not showing up until months or even a year or two later, where I tracked it down to what had probably been a very minor nick in a conductor's insulation which had probably been very hard to see. And connection may have tested and worked well at first. But over time nick had opened, or strand of drain wire had worked its way in, or whatever.

    Usually resulting in partial short, communications didn't go down, just had an increase in error rate. Or sometimes an intermittent short is the result. Showing up as wire moves with heating expansion, going away with cooling contraction (or vice versa); or as a result of vibration.

    My way doesn't look as neat, but with practice can be done very quickly with virtually no chance whatever that you nicked the insulation on any conductor, not even a little bit. No reason to even need to closely inspect.

    I agree with the wrapping of the drain wire back over the jacket instead of over the conductors. Simple insurance, I have seen wrapped drain wires that were tightly wrapped over conductors eventually wear through insulation. Plus sometimes drain wire strands are broken, or the cut ends if in contact with conductor insulation, will eventually bore through conductor insulation and make contact. Again, usually a minor short, just an increase in error rate as versus complete failure. Fold back and wrap and make sure sharp cut ends are on the jacket, not a conductor's insulation.

    And tape it downs securely, with GOOD tape. And I agree with Crab, the more yah finger the sticky side of the tape, the more likely things will unravel in an unreasonably short period of time. Particularly if you're hot and sweaty, or have dust or oil on your fingers, etc.

    Again, my way doesn't look as neat. But with practice it looks pretty darn neat. Can be done fast, in bad lighting conditions that'd make inspecting for nicks difficult, etc.

    It's also the way I was taught by some old hands in the game, some old instrument techs and some controls techs who'd been working with this kind of stuff since it was invented.

    Just my thoughts and opinions, and worth no more than any one else's.
    We preach the same song, grab that pull string and rip another 8"- 12" then cut off the excess and start working. Tape back the shield, folded at the end for removal. Two labels one near the end and another in the panel chase.

  3. #16
    Join Date
    Oct 2003
    Location
    Minnesota
    Posts
    1,376
    Yep, I didn't mention it but we INSIST upon good labeling practice. All our installers have the good label makers, and tape, which can turn out labels for devices and boxes, and labels suitable for cable wrap application.

    Most of them will apply labels to cable ends when the pull is done. Before they get down to dressing and terminating the ends. We have them make labels that make sense. Not numbers. Rather labels that read like, "AHU 1 DAT", "AHU 3 RACO2", "Rm 215 ZT", etc. We have a standard for what we call things, and it shows up on the schematics that the installer is following. For comm cables they're marked in a format like "From ..." and "To ...", with the rest being an identifier for the device concerned. Really not necessary to indicate its a comm cable since (1) label makes it obvious, and (2) the comm cable will be the only one of that color we'll use on a project. We have standards for colors for comm cables. Such and such a colored jacket for BacNet, different color for Lon, different color for Modbus, etc. Non-communications cables will all be white jackets. Helps keep things straight. i.e. I've worked projects where we have AAM's Pup, BacNet, Modbus, and LON all in one building.
    A site where I stash some stuff that might be interesting to some folks.
    http://cid-0554c074ec47c396.office.l...e.aspx/.Public

  4. #17
    Join Date
    Sep 2007
    Location
    Australia
    Posts
    159
    Green sleeving over drain wire, white heatshrink over point where outer insulation finishes (and green sleeving begins) with cable label written on it. Wire numbered of course, even tho I HATE WIRE NUMBERS cos they're so time consuming. Interestingly I read that in Germany in the automation world they were moving away from them...

    Bootlace crimps (which I used to hate but i'm changing my mind in CERTAIN circumstances) on any fine wire or flex, altho i ask the individual BMS guys if they do or don't allow them on any RTD wiring. HEXAGONAL (6 pass) crimper does a much better job too, worth the extra $10.00.

    I don't think you should rely on tape anywhere it's important.

    That said tho, I recently terminated a huge BMS control board, alot of 0-10v and comms etc, which all tested ok after fixing the usual odd mistake, then I realised I totally forgot to earth the shields. They were all connected together ready, but forgot the last wire to ground. And there were a couple hundred cables... Hmmmm
    Also regarding HI VIS, I have a theory that if you get 3 or 4 guys in hi vis you could steal anything in the world in plain sight...
    The DDC system... guilty until proven innocent

  5. #18
    Join Date
    Jan 2001
    Posts
    7,779
    Quote Originally Posted by jrevans View Post
    Am I the only one who prefers to cut their electrical tape (usually with dikes) instead of ripping it? I'm a desk jockey, so maybe I'd do differently if I was an installer and had limited time, but I despise the wavy end of electrical tape that you get from ripping it....

    Good video. I like the idea of wrapping the drain wire back over the jacket.
    I cut my tape with a razor knife...... cut a lot of things with a knife......but Im very carefull and I always look to make sure I have not nicked or scored anything I shouldnt...

    We also solder and shrink wrap our comm wire splices...if we have any. Not terminations...but whenever we have to splice a length together or we cut into an existing wire to add something to the chain.
    YOU SHALL REAP WHAT YOU HAVE _______ SOWN

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