120V Phone and Fiber In Same Conduit

[slushin]

Does anyone know of any standards which state whether or not it is acceptable to run fiberoptic and phone lines in the same conduit? I know what the NEC says, but I'm interested in whether or not this will cause performance issues for the fiber.

 

[VEBill]

Fiber optic fiber? It's perfectly immune to any EMI. The only practical cosideration would be to avoid physically crushing it.

I can't speak to the telephone and power combo.

 

[MikeHalloran]

Copper phone lines in conduit with power wires is a bad idea, because the phone wires are not insulated like the power wires, which >I think< is what the NEC would require to make it allowable.

Running fiber through dedicated conduit should be okay, but running it alongside power wires is a bad idea because it won't like being kinked at the boxes, where no room is provided. As sure as you specify only bent conduit for direction changes, somebody will put in a cast elbow.










Mike Halloran
Pembroke Pines, FL, USA

 

[slushin]

VE1BLL, it is fiberoptic.

They are planning on installing innerduct to protect the fiber.

 

[slushin]

also, the fiber is in a composite cable.

 

[GregLocock]

We used to run 200V power and 3 fibre optics and a bunch of other stuff all together in a 30mm cable. No signal problems.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[DanEE]

Telephone lines depend on the electrical characteristic "longitudinal balance" to have noise immunity.. Look this term up..

Placing telephone wire in metallic conduit can degrade longitudinal balance due to the unpredictable and uneven coupling of the individual wires that make the pair to the metallic wall.

 

[robertjo24]

The folks in the code section (below link) can answer the leaglities of running high voltage and low voltage togerther.

http://www.eng-tips.com/threadminder.cfm?pid=242

As for what is right...high voltage and low voltage should be separated. You can very easliy get noise induced into the phone cable from the power cable. As for the fiber, if it is all dialectric type fiber, I would say it would not violate any rules having it ran with high voltage cable, but again it isn't best practice.

 

[lacajun]

I wouldn't run them together simply knowing what happens in the future. People get confused and start running stuff anywhere and everywhere creating a mess along the way, from the drawings to the field. Decades from now, you'll be retired and someone will call you inquiring about "what's in there" and "what did you do." But, you'll be retired and won't answer your phone, most likely.

 

[IRstuff]

Sure, I would; I'd charge appropriately, too.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[lacajun]

IRstuff, I would, too, but many retirees I've worked with won't answer for anything. Bitterness towards a company can go a long ways with some.