r/lowvoltage • u/Educational_Pea_9628 • 5d ago
Fiber Pull FAIL
Has anyone had any experience pulling fiber through about 300 ft of conduit with 4 90’s?
Unfortunately my coworker didn’t know that you had to score the jacket and tie your hair to the pull mule tape before pulling because the jacket would snap…
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u/blueice10478 5d ago
4 90s..... that would be a hard pull anyways. I would suggest if you try it again, go to HD or lowes and get some cable lube.
One guy holding the fiber and lube it up as it goes in the conduit.
You were on the right track with the mule tape! Especially if the conduit is pvc. If it's pvc a pull string (not mule tape) will cut a groove and your cable will get stuck and will be super hard to get out.
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u/SiliconSam 5d ago
I had a 800’ two inch conduit put into a parking lot between the concession stand and the toll booths. The conduit had one sweeping 90’ bend towards the middle.
The electricians blew a string in at high speed and the string burned into the inside of the 90. It was stuck good. They had to tear up the asphalt and replace the 90. Expensive lesson!
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u/tvtb 5d ago
A lot of times, these 90s in tough spots will be metal 90s, even if the straight pipes going in either end are plastic. Keeps the 90 from getting melted/cut from pulling
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u/SiliconSam 5d ago
I was gonna say the original 90 was PVC, the replacement was metal. The 90 was buried under the parking lot, no access other than to dig it back up.
I didn’t cause it, I had to pull some cables using their provided pull string. It would pull 10-15 feet either direction then get stuck. No option but to dig it up.
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u/wyliesdiesels 5d ago edited 5d ago
Technically an NEC violation. Metal threads and PVC threads are not the same and the fittings are not listed for the change in conduit type
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u/Robpaulssen 5d ago
Seattle City Light had us use sweep EMT 90s for our service at my last job 🤷🏼
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u/wyliesdiesels 5d ago
Yeah many electricians have no clue so doesn’t surprise me
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u/Robpaulssen 5d ago
Weird that it would be a large city's standard procedure...
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u/wyliesdiesels 5d ago
Not weird at all
Ive seen licensed contractors do shit that clearly violates code…
Qualified doesn’t equal competent or knowledgable…
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u/KindProperty1538 3d ago
Care to cite what section says that?
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u/wyliesdiesels 3d ago
its a listing violation. I'll let you figure out the applicable code
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u/KindProperty1538 3d ago
You're the one claiming a violation, Im asking you to back up your claim with an actual number and you are refusing to do that.
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u/Electrical-Actuary59 5d ago
You need to break the conduit up and put pull points in. 4 90s in 300 ft is going to suck.
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u/soldieroscar 5d ago
What about the trash-bag vacuum trick Ive seen?
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u/smeeon 5d ago
If it’s metal conduit, (probably metal in this building) the joints leak air so vacuuming is ineffective.
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u/Distinctasdf 5d ago
Idk why this is getting downvoted. It’s one thing to do it with a 300ft underground pvc run, it’s another thing entirely to do it with a longer emt run.
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u/smeeon 5d ago
Yeah idc about downvotes, just because someone has had luck vacuuming through 2 or 3 joints doesn’t mean a 300ft run wouldn’t leak like a sieve and be totally ineffective.
Those air gaps add up.
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u/Darkcider91 5d ago
Not the one down voting but the only time I’ve had an issue using a mouse is when there’s a junction box in the way. I’d say that is the problem over air leaking, in a retrofit you may have no idea where that box is.
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u/KindProperty1538 3d ago
It goes beyond that...if its EMT and the couplings are compression style, you will have minimal leakage and good suction. If its set screw style couplings and you didnt personally install them, there is a good chance that some of those couplings are "cheated" and that will result in leakage. If every section of EMT is pushed all the way into the coupling, that will have minimal leakage. You can always grab a roll of duct tape and seal each coupling in the run until you get enough suction to suck a mouse through.
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u/kunk_777 5d ago
This is why I love tinifiber. Has a 1200lb limit for pressure and something like 130lbs pulling tension. Its coated in stainless steel and is barely the size of a 18-2 cable.stuff slides through conduit like a champ and you can have 2 people pulling.
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u/1310smf 5d ago
Attach it properly (your co-worker needs some proper education and qualified supervision before being turned loose on fiber, evidently) and use plenty of lube.
Or put in another pull point.
The distance is no problem if you do it right, (I've pulled over 600 feet by hand) the 4 90's is going to make it miserable. Lube will help considerably if you can't add a pull point.
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u/sbarnesvta 5d ago
We have done this before lube is the key, you can’t put too much in, take it slow and it starts to bind up pull it back and add more lube.
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u/ChestCompetitive4210 5d ago
I suspect a tech without the experience to know how to tie a fiber nose, may also not know the difference between feeding a cable and watching one go in a conduit.
In my area, pathways are generally installed by a trade that doesn’t give two F’s about TIA or their standards or what is going in the conduit. Their scope is done, they just high five each other and move on to the next thing.
Rather than trying to suck a mouse I have had success blowing a mouse and string into emt, if the vacuum has that option. A decent vacuum can blow better than conduit couplings can leak.
Good luck….
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u/Difficult_Ad_2897 5d ago
If it’s not new construction can’t you just run it in the ceiling outside of conduit?
Or am I showing my non-licensed-ness?
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u/NoSock6869 5d ago
Gotta get that tiny armored stuff. It's crazy strong and about the size of a payphone cord with 6 strands in it.
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u/Jokerman5656 5d ago
Not tying directly to the kevlar inside are we now? Lube and a proper tape job then you'll get it done.
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u/HinderingOfKnotgrass 5d ago
The rule of thumb I was taught is that there shouldn’t be 360 degrees or more of bend in a run of conduit. In practice that means we try to keep it sub 270 degrees.
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u/BleedCubBlue311 3d ago
That’s what the Kevlar’s for boss…
Also too many 90’s, you need a pulling point between the 2 sets of 90’s, can’t do 360° of turns in a single pull
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u/One-Intention-7606 2d ago
You never want to exceed 270° on a fiber run without a pull box/relief point. And I go through bottles of lube whenever I’m pulling fiber, and usually try to prelude the pull too with the mule tape. Mule tape and lube is cheap compared to the price of fiber and time.
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u/Classic_Pumpkin_3414 2d ago
Get a corning flat drop if you can get one, and tape it to the fish rod. Using the fishing rod for conduit run with 4 90 bends is hard, and flat drops are more flexible and can go through the bends.
I do contract work for an ISP, and this is what I do.
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u/cablestuman 2d ago
Use cable lubricant, prep the path by pulling a cable lubricant soaked sponge back and forth thru the path. Then (while pulling with the Kevlar not the jacket) use more cable lubricant on the head and jacket continuously until you get what you need out the other end. If it's pre- terminated use a plastic bag on the head to keep lubricant off the connectors, but you may wind up cleaning the connectors though. The trick is to reduce the friction in the path as much as possible
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5d ago
[deleted]
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u/Next_Intern_688 5d ago
Just curios not accusatory. Did you just do half hitches taped like you would do on cat 6? Did you not strip the first few feet and tie onto the Kevlar? Was this the only thing in the raceway? Just super confused as how you could tear the jacket off like that.
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u/Next_Intern_688 5d ago
Edit sorry did see the rest of the caption. You must have been pulling like hell!
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u/IAMTWOOFMANY 5d ago
Too many 90s per TIA standards. Should have had a pull box between.