Can anyone give me a tip for estimating the amount to stagger several drops in a cable run? Using vertical drop of 10' and and 10' service loop (customer request) and counting false ceiling tiles but this is still causing wasted cable. is there a mathmatical method or a common standard used to calculate distances between drops? Thx
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Estimating horizontal cabling stagger for drops bfore pull.
- Thread starter wzrdman
- Start date
Unless you are carefully pulling each run individually you are going to have waste no matter what you do. I hate to throw hundreds of feet of brand new cable in the dumpster but unfortunately the alternative is additional labor which is even more expensive and not always the solution anyway.
When you price a job and order cable always include a percentage for waste.
-Hal
When you price a job and order cable always include a percentage for waste.
-Hal
mikeydidit
IS-IT--Management
Hal is right. Regardless of what method that you use, their will be some amount of waste. This still beats the alternatives of pulling some too short and completely repulling them. You can use several things like you mentioned (ceiling tiles, floor tiles, and cinder blocks) to help reduce waste.
Mike Jones
LSUHSC
Mike Jones
LSUHSC
All the Guys are right, what at first looks like waste will save you a lot in labour cost ,
I've been known to run an extra drop or 2 in difficult to reach places (on constriction) just in case the building owner wants more points in the future.
Cable costs nothing compared to time on the job.
I've been known to run an extra drop or 2 in difficult to reach places (on constriction) just in case the building owner wants more points in the future.
Cable costs nothing compared to time on the job.
The best way I have found in the past to cut down on waste is to pull into the Communications Room with the Rack & patch panels in place. Then I just estimate & backfeed at the location ends. I had different techs leave way too much estimating the Comm Room area.
Steve
tele-dataservices.com
Steve
tele-dataservices.com
This method is time consuming but if the cable is expensive or in short supply it can be worth the effort.
1. Get a string (nylon mason string is good) that is at least as long as the longest wire.
2. Attach one end of the string at the location in the wire closet. (leave some slack!)
3. Run the string to the longest wire location and mark the length on the string with a sharpie marker.
4. Repeat for the other locations.
5. Remove the string and measure or cut your wires.
If the drops are consistently spaced you may only need to do a few to get the pattern.
This is really handy if you only have one spool of wire or you need to get all the wires in one pull.
1. Get a string (nylon mason string is good) that is at least as long as the longest wire.
2. Attach one end of the string at the location in the wire closet. (leave some slack!)
3. Run the string to the longest wire location and mark the length on the string with a sharpie marker.
4. Repeat for the other locations.
5. Remove the string and measure or cut your wires.
If the drops are consistently spaced you may only need to do a few to get the pattern.
This is really handy if you only have one spool of wire or you need to get all the wires in one pull.
The time that I find the stagger method to be of most use is when pulling cables for modular furniture. If all the cable will be coming out of one location to feed the cubes it is very easy and helpful to stagger the drops. It will also save you in labor costs due to knowing which cables go where due to their length. As far as staggering runs that will be going to different locations along the same run. I guess that just comes with experience and unfortunatly some re-pulls before you get it right. I use Wires plan when I am pulling the cable from a mid point and I want my back pull to be very precise. If you err too long on the back pull on a big job you can end up wasting a great deal of cable.
Most hardware stores sell measuring-wheel's -- the smaller ones -- for approx $40 CDN.
What I usually do -- and make sure my techs do also -- is keep a bit of a service loop at each drop location. In fact, we try to promote the passive zone system to all of our clients. This way, if there is ever a move, you have that service loop as a buffer -- ie, you can move that line 10 meters in any direction. Any extra length you have on a pull, can go into your service loop.
Also, when you pull your lines, are you pulling them from one box/spool? I've always pulled entire groups at a time (12 spools) from the field to the comm room -- we pull the proper amout of slack on the head end to reach the comm room with allowances for rack location, etc. -- then individually measure the drops and cut from the spool. Never had a problem with waste.
What I usually do -- and make sure my techs do also -- is keep a bit of a service loop at each drop location. In fact, we try to promote the passive zone system to all of our clients. This way, if there is ever a move, you have that service loop as a buffer -- ie, you can move that line 10 meters in any direction. Any extra length you have on a pull, can go into your service loop.
Also, when you pull your lines, are you pulling them from one box/spool? I've always pulled entire groups at a time (12 spools) from the field to the comm room -- we pull the proper amout of slack on the head end to reach the comm room with allowances for rack location, etc. -- then individually measure the drops and cut from the spool. Never had a problem with waste.
Also, don't forget that cable shouldn't go in the dumpster. You should be able to find a recycler that takes cable. Copper cable prices are high right now. We took a truck load full, and got a fairly good price.
Justin T. Clausen
Physical Layer Implementation
California State University, Monterey Bay
Justin T. Clausen
Physical Layer Implementation
California State University, Monterey Bay
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