Tech Tip: The Right Way to Strip Communication Wire for Building Automation Controls
Thanks to our friend Abel aka (thecontrolsfreak ) for this excellent video on the proper way to use communication cables in for building automation controls.
HVAC Tech of 36 years in the HVACR and Controls Industry
Sometimes I want to club "that guy" with a blunt object.
If more government is the answer, then it's a really stupid question.
Originally Posted by mark beiser
I like to club the guy that came up with high vis gear also.
If you can't see me IN A BUILDING then maybe.....
a. you are blind and shouldn't be on site
b. the site lighting condition is below OSHA
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
Amen to that.
Originally Posted by mark beiser
Some good tips. I've found that after a few years electrical tape comes undone and dosen't last.
If you can't fix it with JB Weld, Duct Tape, and Ty Wire it has to be replaced.
No good deed goes unpunished.
If you want to take off friday to go fishing then make sure you train your helper right.
sorry, if you can't strip it/fixit with teeth and fingernails, you are no good technician.
been there, done that, anyway - also gotten laughed at for soldering stranded wire onto an EOL resistor so it would be secure under compression terminal. guaranteed it still works, though.
also troubleshot a nag where glycol had leaked down through a chase, gotten into an upside-down wirenut, and completely corroded the conductors. ugly.
Only use a real ratchet -type crimper now.
I like to use shrink tubing instead of electrical tape. Also shrink tubing comes in clear or other colors and really finishes out a cable. I've also used insulated wires connected to the shields and landed the shields on a grounding block. I totally agree that its the details.
Pretty decent overall but I gotta say I hate it when people get their greasy fingers all over in the sticky electrical tape. It just makes it come unraveled that much faster. Pull out an inch, leave it on the roll and wrap the cable with the tape on the roll then when you get enough wraps, pinch the tape and the cable with your thumb trigger finger and then the tape to itself or your other trigger finger and thumb and pull apart. This maximizes the adhesion.
Also don't use any electrical tape but Scotch 33+ or 88+. If you've used any other electrical tape in hot or cold environments you'll learn why in a hurry, hell even coming back on jobs years later where they've used cheap electrical tape and it's starting or has unraveled.
"How it can be considered "Open" is beyond me. Calling it "voyeur-ed" would be more accurate." pka LeroyMac, SkyIsBlue, fka Freddy-B, Mongo, IndyBlue
BIG Government = More Dependents
"Any 'standard' would be great if it didn't get bastardised by corporate self interest." MatrixTransform
My 5 yr old son "Dad, Siri is not very smart when there's no internet."
That's why I have 2 rolls, the cheap stuff for when pulling wire or doing something quick / temporary. When terminating use the better stuff, at $4.00 a roll it adds up quick especially when the cheap stuff is $.50 in the 10 packs.
Originally Posted by crab master
shrink tape is the only way to terminate, and some jobs I have installed spec it.
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.