Telecom NEC ? for DC Power & Fiber runs

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dwd817

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Texas
Ok, guys I have two senarios I would like some asisstance with.

Question #1: If running outdoor RHW or RHH for DC power up a communications tower is it required to be installed in conduit?

The reason I ask is because most of the ground home runs are THHN (not outdoor rated) that is using cable ties to mount it to the tower. If I was to run RHW or RHH I would use cushioned snap-in type hangers for mounting. If I was not able to run without conduit the wires would need support meaning that I would also have to run a messenger cable therefore needing larger conduit. If I needed the larger conduit, then I would need verify tower wind and ice loading to figure out whether it would even be able to support the conduit at it's current cofiguration resulting in additional costs.

Question #2: If running outdoor rated fiber cable up a communications tower would it require conduit?

Question #3: If running outdoor rated hybrid fiber w/ power cable up a communications tower does it require conduit?

Question #4: If running a outdoor rated armored hybrid fiber w/ power on a rooftop does it require conduit or is cable tray sufficent?

I have looked over the NEC and find conflicting information or nothing that covers these scenarios, any assistance would be apprecaited. Thanks.

Dennis
 
Not necessarily an answer to question 1- what do the plans call for?
side note: most thhn is also thwn which can be used outside.

2.possibly not

3. possibly not

4. I would think cable tray would be acceptable.
 
I may be sticking my neck out here but I don't think anything on that tower falls under NEC jurisdiction. It would be under the exclusive control of the utility.
JMO
 
qcroanoke said:
I may be sticking my neck out here but I don't think anything on that tower falls under NEC jurisdiction. It would be under the exclusive control of the utility.
JMO
Click to expand...

I agree 90.2(B)(4)
 
Hi barbeer,

THWN is not rated for UV from my understanding and shouldn't be used outside without conduit especially in Texas. On the other hand, the RHH & RHW are (UL Sunlight Resistance for CT use; Oil Resistance II per UL 44) so this works for me.

As for the plans, the product this stuff is hooking up to is from overseas where they don't have the codes requiring conduit, this makes the solution cost effective overseas. For this reason it also makes the plans irrelevant for US applications.

Most of the time the electrical code inspector is looking at the power coming to the site and AC panel and really never looks at the tower accept for maybe the grounding. The building code inspectors look at the tower construction and structural plans but rarely look at the electrical running on a tower (i.e. warning beacons & stobes for example, sometimes in conduit, sometimes using outdoor rated cable). Again, any help would be great.

Dennis
 
I agree 90.2(B)(4)

Thanks that works for me. Just need to find out the definition of the comminucations utility (i.e. the tower owners or the equipment owner's or both).
 
I am not sure that a communications tower is a "public utility" installation for the purposes of 90.2(B)(4).
 
Main Entry: public utility
Function: noun
Date: 1903
: a business organization (as an electric company) performing a public service and subject to special governmental regulation

The equipment would be for a service provider. Does this not fit?
 
Regards conduit- in some areas of the country, it is considered sport to shoot out tower lights, and since the aim usually isn't very good, that can take out other cables attached to the tower. I know a radio station (5kw FM) that had to replace the heliax on their tower because of this. So, given a choice (and the $$$$), I'd suggest some form of physical protection.
 
wireguru said:
ugh, who the heck would want to terminate fiber on the top of a tower.
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Well sounds like they are putting up a data link. With DC power going up with it, me thinks the terminal equpment is tower mounted to avoid signal degration. Pretty common for WiFi.
 
wireguru said:
ugh, who the heck would want to terminate fiber on the top of a tower.
Click to expand...

I have one tower I take care of with fiber...it's only 100' tall. We put a 3" RMC to the top for various LV stuff, and it was natural to pull the fiber in that pipe. We made up the fiber ends on the ground, wrapped it in bubble wrap and pulled it up the pipe (easy to do with 3" conduit!)

Regarding the OP, I haven't read article 770 lately, but I don't remember anything about outdoor fiber protection. If I'm wrong, I'm sure you guys will let me have it. :grin:

zbang said:
...in some areas of the country, it is considered sport to shoot out tower lights...
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Make that most everywhere. I have one tower site with a temporary patch on a Heliax with a bullet hole in it (permanent repair hopefully before winter), and a transmitter building with several bullet holes. One bullet bounced off the transmitter cabinet...I found the slug on the floor.
 
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