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#605739 11/23/16 02:52 AM
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meisgq Offline OP
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I need some guidance as to how to properly support a vertical data cable run. For example, if I have machines in a warehouse that require network drops from the rafters to the machine at 6' above finished floor, how should the cable drop from the ceiling to machine? We've used various solutions in the past but I get the feeling that we're doing it wrong. We've had techs tie cables to flexible power cords with strain reliefs (not correct), run cables inside EMT secured from rafters to the machine, and free-run it from the rafters with only a loop at the top as support. I've thought about using flexible cords or FMC as conduits but that didn't sound right. Any advice would be appreciated. I want to get this right.


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meisgq #605740 11/23/16 03:46 AM
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How high are the rafters- in other words how long is the drop? There is no magic solution here. If you want to spend money they make "power poles" that you will see in stores dropping down to the POS terminals at the checkouts. These handle both power and data. I think in your case EMT conduit is a good choice. I would choose a large enough size to minimize flexing- depending on the rafter height.

-Hal


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meisgq #605741 11/23/16 04:08 AM
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They are about 20ft high. They only require 1 cable per drop so a power pole would be overkill. I'm thinking 1/2" EMT but I believe EMT also has to be secured at least once every 10ft. Basically, if you have two sticks of EMT hanging from the ceiling, it is not legit. That's why I'm having such a difficult time trying to determine the code-compliant method.


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meisgq #605742 11/23/16 04:44 AM
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I'd have to double check, but I believe you could run a piece of strand from the ceiling down to the floor and support the cable to it. (Basically an OSP horizontal run brought indoors and run vertically).

For a 20' drop, you wouldn't need much of a strand (¼", maybe...)

You could also run kindorf (unistrut) from the ceiling down to the door and use it to support EMT. Or just tie the cable to the unistrut. Not as pretty, but cheaper.

I'll think more on it tonight.

Sam

Last edited by Silversam; 11/23/16 04:48 AM.

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meisgq #605751 11/23/16 03:45 PM
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Quote
I'm thinking 1/2" EMT but I believe EMT also has to be secured at least once every 10ft.

Secured according to what? The NEC has nothing to say about something like this. 1-1/4" with a steel setscrew or compression coupling and secured at both ends. Bob's your uncle.

-Hal


CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
meisgq #605756 11/23/16 05:56 PM
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Hal -

I agree that the NEC doesn't care about conduit for data wiring, but I do believe that two lengths of ½" EMT, even if secured at both ends would probably come apart at the coupling soon enough. Between vibration and banging I wouldn't trust them to be secure. ½" Rigid pipe m i g h t hold together but personally, I think unistrut & emt with 2 straps per length of tubing would certainly do the trick. Not too difficult, not too expensive and certainly secure.

Sam


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meisgq #605760 11/23/16 09:46 PM
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The only problem I have with Kindorf or Unistrut and 1/2" EMT is that the clamps are designed for the pipe crossing the channel at 90 degrees, not running parallel to it. I think Caddy may make something that will work but the sizes are for copper tubing.

-Hal


CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
hbiss #605761 11/24/16 02:36 AM
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What about tie the cable to fixture chain?

hbiss #605771 11/24/16 05:27 PM
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"The only problem I have with Kindorf or Unistrut and 1/2" EMT is that the clamps are designed for the pipe crossing the channel at 90 degrees, not running parallel to it."

¼" kindorff nuts and "Mae West" (mineralac) clamps.

Works for me.

Sam


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meisgq #605777 11/24/16 09:56 PM
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Why not just use a piece of clear clothesline wire. Support top & bottom & be done with.


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