Fiberoptic cable is literally made of glass. Crazy, I know! But, because of this, the cable can be pretty delicate. So, here are five handling tips for fiber patch cables that will help you keep your cables in good working order.
The “bend radius” of a cable is the term for how sharply a cable can safely bend at any given point. All cabling has a bend radius, and this radius can be unique to each type and make. I’m here to help simplify these things for you so I’m going to give you a rule of thumb rather then a detailed specification.
So, here is you rule of thumb: You don’t want a fiber cable to bend at any given point with a radius less then 10 times the diameter of the cable. For a normal fiber patch cable, this is no shaper then if it were bending around a tennis ball.
If you bend the fiber cable more sharply then that you can have a couple issues.
- The glass in the cable could break or shatter causing reflection and refraction of the light running through the cable; i.e., the cable starts to really suck.
- When a fiber cable bends too sharply the light passing through the cable will reflect too steeply and not make the turn. Because the light bounces off the walls of the fiber whenever the fiber bends it can’t bend to steeply. If it does, the light will reflect at too steep an angle and will be absorbed by the cable or make a u-turn and head back the way it came.
Cap Your Connectors
Fiber cables aren’t cheep and the tips on the connector can easily get damaged, smudged, etc. So put a cap on those babies. Because light goes through these cables minor things can cause big issues for you. Things like touching the tip of the fiber cable with your finger or letting dust settle on the tip. Dust, finger oil, etc. will all cause the light leaving that patch cable to reflect and refract causing loss and making the cable less efficient or un-usable.
Don’t Strap Too Tight
When you secure a fiber cable to another cable, cable tray, etc. make sure you don’t tighten the zip-tie, velcro, twisty, or whatever your using too much. Over tightening the securing straps apply pressure to the cable that may cause the glass inside the cable to warp or break, and make it more prone to failure over time.
You want the cable to be secured reasonably snuggly, but it should still be allowed to slide through the securing strap without much force. If you have secured the fiber cable to the point where it will not slide back and forth through the securing strap or the fiber cables jacket looks like it is being squeezed, the it is too tight.
Keep off of Sharp Angles/Edges
When installing fiber cable or dealing with extra slack from the cable, keep the cable from running off sharp angled edges like that of a table or shelf. The reason for this, once again, that the glass may warp or break over time due to the pressure on the cable at the sharp edge. Believe it or not, the weight of the cable being pressed against such a small point is enough to break or warp the glass inside to a point where it will cause light loss or outright failure.
What is really going on here is a re-hash of the whole bend radius point above. Just with a slightly different take. If you run a cable off the edge of a shelf the bend radius may be fine… at first. But if that edge doesn’t have the proper arch to it, the cable will sag and start to exceed the bend radius over time.
There are products out there that can help your cables in these situations. You can buy cable management bend radius clips, or cable “waterfall” accessories. Panduit is a quality, and sometimes expensive, company that manufactures these products. If you are just putting a switch on a shelf (<angry face>which I don’t advise, but you may be doing it anyways </angry face>) you could use something like pipe insolation of a pool noodle on the edge of the shelf to keep the cable bend radius correct.
Becomes More Brittle Over Time
Fiberoptic cable becomes more stiff and brittle over time. I never thought about this when I first started working with fiber cabling, but in my experience, it is true. I noticed that older cables, even if they are in the packaging still, were much more stiff then the newer cables and were just more prone to being broken.
You may notice if you pull a fiber cable out that has been installed for a few years that is will just old the shape it was in from the time it was installed. The real lesson to be learned here is be very carful around currently installed fiber cable and move installed cabling around a little as possible.
To sum it all up, when handling fiber cable: don’t bend it to tightly, don’t squeeze it, keep the ends covered all the time, and (like cooking fish) don’t poke it too much. Hope you found these few tidbits of information about fiber useful.
What are your tips on handling and maintaining fiber cable?