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.

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

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.

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

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

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

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

What about tie the cable to fixture chain?

"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

Why not just use a piece of clear clothesline wire. Support top & bottom & be done with.

I have a production lab that has 30 data drops to equipment with a 22' ceiling height. We used unistrut supported at the ceiling and floor. The conduit was connected to the unistrut with Minerlac 0B clamps. I have found nothing I like better.

Rcaman

Uhh, how could I forget those. You Guys are right. We call them "cowboys".

-Hal

Sorry for the late response.

Sounds like there are basically two options:

1) Install a vertical piece of unistrut to support EMT
2) Install a strand of rope or support wire and strap the cable to it

Option 2 looks like the better option for a single data cable. Faster. Cheaper. Cleaner.

I've encountered similar applications in commercial kitchens (actually school kitchens) where we needed to get network cables to the electric ovens and fryers, plus the POS terminals when the GC forgot to put pipe in the slab.

We screwed a 3/4" plumbing flange to the floor, SEE PICTURE HERE, added a 12" X 3/4" galvanized threaded nipple, then threaded a 3/4" X 3-hole FS (weatherproof) outlet box onto it. Of course, you can use any length of pipe from the floor flange to the bottom of the box.

From there, we would thread a full 10' length of 3/4" rigid conduit into this box and, if more height was needed (we're at almost 12 feet in length at this point), another portion of conduit was added. With everything being assembled wrench-tight, it's pretty solid, even with 20 feet of pipe.

In our installations, the box was fitted with the appropriate devices and we placed weatherproof covers to protect from the usual cleaning overspray.

Weatherproof outlet boxes are generally made with cheap aluminum alloy, however you can get type FS boxes made of galvanized cast iron ( LIKE THIS ) through an electrical supplier. They are solid as a rock if you have a harsh environment. If you're going more than 10' above the box, I would recommend that you spend the money on these instead of regular aluminum alloy ones.

Our final attachments above the ceiling were done using traditional fastening methods, such as threaded rod, Minerallac conduit clamps and Unistrut/Kindorf hardware to attach to the building structure.

I was going to suggest the same thing- RGC with a flange and FS box but I didn't think the OP would go for it. And you can get 20' lengths if you go to a plumbing supply.

-Hal

We did one job using pipe flanges and rigid conduit. It was for a coal mine lab and MSHA required everything to be explosion proof. It was a lot of mechanical work and we actually hired a "mechanic" (only an electrician knows what I'm talking about) to do most of the rigid bending and intricate saddles and offsets. I'm not bad at it, but when the job was done, it looked like a work of art. It was well worth it to have the "mechanic" on the job when MSHA actually used that installation as an example of how to do it "safely and properly."

Rcaman