underwater fiber

SockMan!

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Is there any special kind of fiber that's needed if I want it to run it under several feet of standing water? Or would any kind of fiber do?

Is there anything else I have to consider when running fiber underwater?

I'm considering running fiber between two buildings through metal piping that's at least a foot below a paved parking lot. There's a manhole in the middle of the parking lot where the piping opens up. It fills up with at least a half-dozen feet of water and the cables are just hanging from the pipe ends a few feet below the top of the water (the last time I checked anyway, I don't know how much the water level varies). The pipe ends that are inside each building are filled with expanding foam.

This fiber is for Ethernet.
 

SockMan!

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sorry, are you running it through a conduite?

It's a steel pipe about two inches in diameter. It's got a few cables in it already; they don't look like they run power. It's probably just some phone lines and a serial cable.
 

marley1

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why are wires exposed to water in the middle?

doesn't sound kosher
 

Jay_2

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why are wires exposed to water in the middle?

doesn't sound kosher

didn't notice that they where exposed to the water... re read it.

I would have that sorted, also if there is copper running between the two buildings then I would also make sure they are both earthed correctly or you could find the PD will destroy what ever is on the other end.
 

SockMan!

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why are wires exposed to water in the middle?

doesn't sound kosher

I don't know. It was run long before I started working here (small/medium business). There's no way to keep water out of the manholes; I just hope those existing wires are rated for outdoor/underwater use (we haven't had any problems so far).
 

SockMan!

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if there is copper running between the two buildings then I would also make sure they are both earthed correctly or you could find the PD will destroy what ever is on the other end.

I'm not running copper Ethernet partly because I'm concerned about differing grounds and lighning strikes. The other reason is that the buildings are about about 300 feet apart. That's quite a distance for copper ethernet - especially considering the less than ideal condition that the cable will have to go through.
 

Concentric

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Hold on, so this 2-inch diameter steel pipe is inside the larger pipe that carries water? So the wires/fibers arn't actually in the water?
 

Jay_2

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if the water is going to touch the fiber then no I wouldn't do it, if the water isn't going to touch the fiber then yes I would do it.
 

SockMan!

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Hold on, so this 2-inch diameter steel pipe is inside the larger pipe that carries water? So the wires/fibers arn't actually in the water?

Sorry about the confusion, let me clarify:

There are actually two pipes (both of identical make and material). There is a manhole in the middle of the parking lot where each of the pipes end. So basically, I'm pulling the cable from building A to the manhole (pipe A), then pulling the cable from the manhole to building B (the second pipe B). The manhole just has the cables hanging in mid-water between the two open ends of the pipe. I can't keep water out of the hole, so the cables are exposed to water as a consequence.
 

Jay_2

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no, i don't think its a good plan. Get yourself a small plastic tube to run through the pipe and run your fiber though that. Make sure the tube goes all the way from A to B and don't bend the fiber to much or you'll crack it.
 

AMD_RULES

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the only thing you should have to consider is that the fiber cable doesn't go around sharp bends, but smooth curves around corners or such...
 

SockMan!

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no, i don't think its a good plan. Get yourself a small plastic tube to run through the pipe and run your fiber though that. Make sure the tube goes all the way from A to B and don't bend the fiber to much or you'll crack it.

Thanks for your advice, but your idea is not possible in my case; I can't run any additional tubing/piping. So that means if I run fiber it'll have to be underwater - hence the reason why I'm asking for advice about running fiber underwater.
 

bealzz

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Go for it, doesnt matter if fibre gets wet at all. It also doesnt carry and electrical charge so you dont have to worry about that either, the only thing I would be worried about is if it gets covered in water and then freezes which might break that cable. If youre someplace warm theres no reason not to. Do it, but like people have said, make sure theres no 90 degree bends anywhere and you should be just fine.
 

smizack

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Go for it, doesnt matter if fibre gets wet at all. It also doesnt carry and electrical charge so you dont have to worry about that either, the only thing I would be worried about is if it gets covered in water and then freezes which might break that cable. If youre someplace warm theres no reason not to. Do it, but like people have said, make sure theres no 90 degree bends anywhere and you should be just fine.

What he said.

Plus, I've made some pretty tight bends without any problems.
 

Jay_2

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Depending what is in the water I would not run it through water if you have to then just wrap it in heat shrink where it will be in the water.
 

SockMan!

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Thanks for the responses everyone!

It seems that my only worry is cold temperatures and freezing (and sharp bends of course). I'll probably need to check if the pipe is below the frost line; if it is then I think I should be good.
 

SockMan!

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Depending what is in the water I would not run it through water if you have to then just wrap it in heat shrink where it will be in the water.

It's just some runoff water with a bit of mud and road salt. It appears that the manhole and piping are clear and fairly sealed from animal and plant life.

What's the heat-shrink tubing for? I don't think it'd be a good idea since it may trap water. It also looks like our fiber will be submerged in water the entire distance, so heat-shrink tubing the entire fiber isn't practical.
 

RoBo

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Let's put it this way, the fibre will work down there, but it will decay. How quickly? Who knows.
 

Grentz

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Let's put it this way, the fibre will work down there, but it will decay. How quickly? Who knows.

Exactly.

I would just do it, obviously the other cables are working fine and have been there, so the fiber should be no problem. And it is better as it does not carry a current.
 

The Spyder

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I have seen a "encased" fiber for direct burial. Its fiber in a 3/8" plastic casing/tube.
Couldnt you run something like that inside the 2" pipe? Its not much larger and its sealed from the water.
 
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