Open Ceiling Cabling Question 1

[grundy]

I have a client who is moving to a building with open ceilings. Do you guys suggest running the cables in conduit in the open ceilings (14ft) or just using bridle rings? What about cable trays?

Will I need to use plenum since the ceiling is completely open (no drop ceiling). 2 rooms will have drywalled ceiling

Thanks

 

[AvayaNovice]

Check with your codes first, but plenum cable is designed to actually be used IN airducting, or "return air" cielings. Your situation doesn't apply to either one of those, so no. Return air cielings usually use the cieling space as a vent shaft. Open cielings are required to have adequete ventilation (spelling...).

Next.

Open cielings usually have trusses, and if they're spaced closely enough together, you can actually use those (although I would be very careful so as not to damage your cable while pulling it).

Using a tray is another option, snaketray is very nice... or flex tray, or a typical "ladder rack" is OK too.

As far as using conduit, sure thing...

I would reccomend using conduit for ALL backbone connections (at the minimum, use innerduct of some sort) and definetely for all closet to closet feeds, if that applies.

Conduit is cheap, easy to work with, and gets the job done.

I would check with code first though on the plenum question, in my area that's how it works.

 

[grundy]

They are planning on haveing 1 MDF where phone and network hardware will be. The T1 will be brought into there.

You recommend having the T1 brought into the MDF in conduit? hmm never thought of that.

 

[AvayaNovice]

Most definetely.

I would place it in innerduct, without a doubt.

 

[Sphoneman]

If your question about cabling will be to install CAT5,6, or 7. NO Bridle rings- minimum of "J" (saddle) hooks to spread the weight load of the cables on the hangers. Codes state supports at 5'. If you have to support by trapezes with strut- you might as well go with basket tray at least for the main distribution, then you can branch off with J Hooks for the offshoots. The last open space I installed in an office environment was a .com & they wanted to see the tray & cables. I would definitely install any fiber or T-1 extension in innerduct as AvayaNovice recommended.


Steve
tele-dataservices.com

 

[AvayaNovice]

Yeah, if your client is anything involving techie type stuff, spec out with good products as my main man Steve said.

Otherwise... you're stuck with the cheapest solution possible.. which isn't fun for you.

 

[grundy]

Thanks for the all the advice. I need to run about 95 Cat5 cables. You guys are saying no bridle rings, J Hooks or a cable tray. I think a cable tray is out ebcuase this building is just too big.

 

[Sphoneman]

You are saying too big, but your main run coming out of your MDF will be a good amount of weight with 95 cables, & will require more supports than 5' to maintain sag minimums until it starts splitting off. You will also need to support the cables coming down, so that the stress is not all on the last hanger. That's what is nice with basket tray-you can conform it nicely to keep the bend radius.

"You instal it once, you maintain & add to it forever"

The appearance is much better with basket tray.I used my pictures to show other clients.

Also if the space can be expanded- you will find yourself dealing with it later, which is not as much fun.
Good Luck,

Steve
tele-dataservices.com

 

[Sphoneman]

You are saying too big, but your main run coming out of your MDF will be a good amount of weight with 95 cables & about a 4" diameter of the bundle, & will require more supports than 5' to maintain sag minimums until it starts splitting off. You will also need to support the cables coming down, so that the stress is not all on the last hanger. That's what is nice with basket tray-you can conform it nicely to keep the bend radius.

"You instal it once, you maintain & add to it forever"

The appearance is much better with basket tray.I used my pictures to show other clients.

Also if the space can be expanded- you will find yourself dealing with it later, which is not as much fun.
Good Luck,

Steve
tele-dataservices.com

 

[grundy]

So basically everyone is saying cable tray is a must with that amount of cable? I was set on using J hooks and just supporting often?

I wonder what Daron's thoughts are...

Thanks

 

[daronwilson]

This is one of those matters you may want to put back on the owner and have them determine how they want it to look. I've seen it done all the ways suggested, and wow can it look butt ugly if the lighting design is poor. Good lighting design can make it so that most of that overhead cabling is hardly visable.

There are lots of ways to support that amount of cabling including multiple runs of j hooks, but for that size of run if you have a ways to go before it really branches off much I would be in favor of cable tray. Of course this adds to the cost and it takes a bit of time to install. If you arent going to do cable tray, there are some pretty inexpensive nylon and cloth like support systems that will hold a bundle of wire that large with no problem. One nice thing about those is you can pull wire like crazy to where you need it and then neatly lay it into these supports. Of course too much wire and the ones on the bottom of the bundle get crushed, check the manufacturers recommendations for maximum cable bundle.

From my experience, Snake tray is probably the fastest to instal and the easiest if you have many changes in elevation or direction.

This is more about what the owner wants to pay for in looks than it is about methods of support, there are many options you could use successfully. I would also agree that protecting the backbone may be worth the extra effort. I piece of 1" innerduct is pretty cheap protection and allows a quick upgrade if needed without disturbing the horizontal cabling installation.

Good Luck!

It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[wires]

Where is a good place to get Snake Tray? I checked the Graybar catalog and come up empty.

 

[smegecki]

Alltel? You may also be able to google it.

http://www.snaketray.com/

 

[Sphoneman]

The one other thing I would like to mention is that I myself(as a personal preference & liability issue) would not use those nylon/cloth hangers.

My main reasoning is that for fireman friends of mine,it would take longer before the metal would give before it might fall down on them. That is the main reasons for the NEC codes which fall under NFPA.

It's just a comment.

Steve
tele-dataservices.com

 

[daronwilson]

Interesting point on the type of hangers. Having been in the fire service for 8 years in a former life, I'm familiar with the codes and how we got them. I assumed the nylon and reinforced cloth type hangers met the same requirements for support issues as did the other products, but now I'm curious.

It certainly could be a concern I suppose, but in my former career in that field I really can't remember it being an issue that I confronted in the field. Good point however, I'll have to do some research.

thanks!



It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com

 

[grundy]

So is there a J hook that can handle 96+ cables in a bundle, or would I have to split it two seperate runs with J hooks?

Are there any other alteratives to using cable trays? Just want to make sure I offer every option to the owner.

Thanks!

 

[franklin97355]

Here is a good source of info:

http://www.erico.com/products.asp?folderid=40

 

[buitenhek]

Great Info above.
Here are my 2Cents
-Definite J hook layout or if conduit
-Conduit size = .24" Dia 95 cables
4" for max 40% fill
actual 37% fill with capability to 102 cables
remember 40" bend radius for 4" conduit
or
-Tray 3"x3" for a 51.9% fill
or
-Tray 3"x4" for a 38.9% fill with capability to 104 cables

Basic project info (your actual may vary)
95 cables = ~50 voice/data locations (avg distance = 152')
1. faceplate cost $67.17 per location
2. faceplate sell $105.36 per location
3. data cable - 7600'
4. voice cable - 7600' (assume lower grade than data cable)
5. 76 hangers (36 cables per hanger & $2.10 per hanger)
6. voice - 1-50pr 1-200pr block (usually 300pr cheaper)
50 pair for spare (10 voice)
7. data - 96 port panel (I like 2-48 port)
46 ports for spare
8. Material cost $1972 labor cost $1782 (68 hours)
9. Sell $5821
10. GPM 35.5% ROI 55.1% profit $2067
Most people will say this is too low, but I would be curious as to your actuals.

Regards
Peter Buitenhek
Profit Developer.com

 

[Sphoneman]

daronwilson,

I have another friend of mine whom is an estimator for a larger firm & he was a Fire Chief in this previous life. He agrees & does the same that I have been doing. Just a small price the customer pays for one less lawsuit, & CYA for us.

If you find out more in your own investigation , please post.

I have witnessed no supports on my jobs with other low voltage contractors/electrical contractors performing Data. Inspectors don't always look when they see our work, presuming the same company is doing it all. I have also seen too much after the fact work.

I have also noticed & read about, which the NEC 2002 code now addresses, about removal of abandoned cabling during retrofits.

I have also seen other jobs- & there is a new generation, not even aware of codes-that just makes me sick when I see it- because everyone thinks they are Telecom cabling techs.

All the strides we went through since divesture, with all the fly by night outfits, or the older Tip & Ring Ex-Bell techs that just looped everything & expected electronic key systems to work.

Okay, I said it, & now am having a Scotch.

Feeling better already.
Thank you-Elvis is leaving the building.

Steve
tele-dataservices.com

 

[grundy]

If 90% off the office is an open celing but say 2-3 offices have a drywalled ceiling will I need to use plenum over the drywalled ceilings? Not sure if they condsider that a compartant.

Warehouse ceilings 14ft
Drywall Ceilings 9ft