still more cabling! 1

[jeffmoss26]

I have been working for my dad’s company all this week.
We are cabling a big building for voice, data, and video. (4 installers counting me)
It has been fun, but it has certainly not been easy. Putting 16 cat 5 cables into a 3/4" conduit is hard! luckily the entire place has conduit, so we don’t have to do any drilling or overhead stuff. I did another small job where I had my head up in a drop ceiling for a long time trying to get cables through a pretty much filled conduit.
But, I am learning ALOT about the business. I knew most of the technical stuff, but the installers have showed me lots of tricks of the trade. All of these guys have been working in the industry for quite some time. And, once I am done, I get the scrap cable from the job. Hopefully, I can get a “real” job with them next year and I will be paid.
Just thought I would share my experiences so far.
Jeff Moss
Warwick Communications, Inc
jeffmoss26@adelphia.net

 

[daronwilson]

Well Jeff, I hope you made a typo in your diary of today's activities. There are a few guidelines for installation of Cat5 wire you might want to review.

1. Maximum Conduit Fill - according to the National Electrcial Code, percentage of fill for electrical conduit is limited to 40% for multiple conductor installations. In short, this means that for 3/4" EMT conduit you are limited to 4 Cat 5 wires. The inside diameter of the 3/4" EMT (.824 in) yields us .533 square inches to work with. Now, consider that Cat5 wire is (generally) .250 inches in diameter, each wire would occupy .049 square inches. Quick division shows us that the 3/4" EMT if filled 100% would allow 10.8 Cat5 wires, or basically 10 wires. BICSI is a bit more conservative in this area, and according to table 4.10 in the TDDM allows for a maximum of 3 Cat5 cables for a 3/4" conduit.

2. Maximum Pulling Force - The maximum pulling force that should be exerted on UTP cabling during installation is 25 pounds. What makes 25 pounds so special? It is at about 25 pounds where soft copper 24 gage wire begins to stretch. Now you can imagine what happens to the twist and integrity of the wire when you stretch the actual conductors. It distorts the wiring terribly. Generally if one has to pull more than 25 pounds, you have too many wires or too many bends or too small of conduit. You can fudge on this a bit if you lubricate the wire as you install it in the conduit. Sometimes you have to re-rig your pulling set up, or add a pull point along the way to pull to and then pull on from there, or sometimes even resize the raceway to accomodate the pull.

Unfortunately architects and electrical engineers rarely seem to catch on to this concept, so in the field it is not uncommon to end up with three boxes in series on one 3/4" conduit run. Of course then the customer wants 6 drops at each box and you are stuck. Conduit runs where the boxes are in series should increase one trade size for each box in the series run. For example, if you have three boxes looped together, the entry point should be 1 1/4" conduit to the first box, 1" to the second, and 3/4" to the third.

Good Luck


It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[jeffmoss26]

thanks for the advice. i may be wrong on the size of the conduit used for those runs. when we pulled any of the cable, we did use wire lubricant since we had lots of twists and turns in the conduit. note-there were 3 runs of 16 cables each in the auditorium. the electrical contractor ran conduit from there to a closet in the front of the room. We just had to pull those 48 cables which will be terminated to a patch panel later on.

today, we installed 85% of the coax cable needed. We did almost all of the classrooms and now we have to run 2 more rooms and a feed in the IDF. We also pulled a few Cat 5e voice and data runs. Ameritech was installing their side-underground feeders and SNI. Now we have to pull voice and data for the classrooms and finish the coax.
I will let you know how tomorrow goes.

Jeff Jeff Moss
Warwick Communications, Inc
jeffmoss26@adelphia.net

 

[daronwilson]

Well I hope you were wrong on the size, and I hope the conduit had no more than the NEC allowed 360 degrees in bends without a pullbox. Again if the building is done to EIA/TIA standards, you would likely have no more than 180 degrees without a box. The key point is not exceeding the pulling strength. If you feel the jacket separate from the wire, or if when you are done you have more jacket than wire on the end you pulled, you pulled too much.

Anyway, today we got a call from a customer with a PBX down, ran out there and troubleshot it then replaced the bad cards and reloaded the software. For the rest of the day we installed equipment for a microwave link between two buildings. We cut a hole in the roof, and extended a mast to mount the antenna on. Then we added power and an ethernet jack in the attic for the radio. Always nice to work outisde when the weather is good. As with any installation of this type, we grounded the mast for safety and the antenna feedline will have a lightning arrestor to protect the equipment. The rest of the day we spent updating CAD drawings from a fire alarm system we just installed and creating O&M's for it. Oh yeah, also we set up a wireless alarm system to enroll the devices and get it ready to install this week.

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[jeffmoss26]

i know we didnt exceed the pulling strength. we had some hard pulls, though. i think that the only bends were from the wall to the floor where the conduit stubs up. we just used a ton of lubricant on the cables to get them through.
my one complaint is that when the electricians ran the conduit, the used a machine that blew a tiny string through the conduit. we had to attach our poly line to it, pull that through, and finally tape our cable. All this for one coax cable!
Jeff Moss
Warwick Communications, Inc
jeffmoss26@adelphia.net

 

[daronwilson]

Blowing string through is pretty common. If it is real tiny like dental floss, I think the breaking strength is about 50 pounds. Normally we use jetline, which is more like kite string, and has a breaking strength of about 90 pounds. Either one should be fine if you aren't exceeding the pulling strength of the Cat5. If I break a jetline installing the cable, I know I have a problem. One note on string, the game is different in PVC conduit. Small string, poly pull string, etc. will burn a groove in the corners of the PVC. You always want to use mule tape when you are pulling much in PVC with bends to avoid burning a slot and melting the string into the pipe.
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[MasterRacker]

Jeff, I think you said it's your dad's company. Have him sign up for Cablining Installation & Maintenance magazine. They have an online version here:

http://cim.pennnet.com/home.cfm

He'll qualify for a free subscription. They do monthly featurs on various installation and how they were done. They also have monthly "Installer Tips". You can pick up a lot of good info there.
Jeff
No matter how bad it is, it can always get worse ....

 

[jeffmoss26]

well, i am all done with this job.
we pulled most of the cat5e voice and data today. the guys have to go back and finish that, then terminate it all. Then they will install the phone system and computer stuff.

I am really glad that I had the chance to work on this job. I learned a lot about the cabling installation process.
Now I have lots of scrap cable from there to use in my shop.

Thanks for the advice,
JEff Jeff Moss
Warwick Communications, Inc
jeffmoss26@adelphia.net

 

[jeffmoss26]

well, i thought i was done. I spent 2 more days this week working on this job. We pulled our phone feed cables and some Cat5e's to extend the T1. I had the "fun" task of terminating all the jacks in the building. I also got to help terminate the feed cables at the blocks and patch panels. the other installers still have much more to do yet. jeff moss
jeffmoss26@adelphia.net