Cable Tray: Seperation of Pwer & Data/Telephone

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starbright28

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Hello all

I was doing a search to see if there is much on the cable tray issue, and I couldn't see much.

I'm designing a project that involves cable tray, and I am trying to understand which code book part (and terms) that I am supposed to be paying attention to. I undertstand, and have read, the section on Cable Tray.

I can't seem to find much on the seperation of Power and Data/Phone. I know it has to be done, but can't seem to find the requirement.

Also - has anyone done the tray fill for wires, in determining on how many you can put in a tray. Basically I am asking how do you do that type of calculation.

And I know only certain types of cable are allowed in cable tray - and I read something about THHN, so how do you know without actually looking at the cable - when you are doing the design work aspect of it?

Thanks for any help, comments, advice.
 
I want to ask more less the same question, from my voice and data notes I recall to refer to article 800.133 of the NEC, but since I only have the 2002 ed. I didn't find that article.

Maybe you can check it and tell us if there is some information regarding the separation of electrical conductors and data/telephone cabling, specially for cable trays.

My specific question it what is the specified separation for 13.8KV lines and data/telephone cabling?:confused:

Thanks.
 
B-Line has a great Cable Tray handbook, call your local rep and ask for a copy. You may be able to get a copy of the NEMA cable tray standard as well.
And of course the mfgs catalog for the type of tray you are spec-ing
Separation is required for limited energy, telecommucations etc from non-wiring methods, ie you don't need for a cat 6 and MC cable in the same tray, but you do for tray cable.

For each wiring method, the uses allowed will list if it can be run in tray, for example see 334.10 (4)
 
Power and Control Cable: type TC can be found in article 336

Power limited cable can be found in article 725.61 (C) and 725.82 (E)

Then the usual article 392.

There are some good sites to visit out there too;

http://www.cabletrays.com/faqs.html

http://www.b-line.com/product/index.asp

B Line is nice for me, because parts are always readily available in my area....might be different where your at.

When designing cable tray runs, consider stacking. One level for power, one for communications, one for data, on bigger jobs. Leave enough room between so that it is workable( 2 foot between decks would be great from a crafts perspective...cost analysis may suggest different)!

Conductor installation is something to consider also in regard to pulling. Takes lot of manpower, or a lot of proper gear to set up, and pull conductors/cables in, and secure in place.

Didn't say I like cable tray, just consider it a smart way to do jobs a lot of times.

Adrian,

Can't give you a technically correct answer, But I'd skip any thought of a divider, and think about two different trays. Watch your radius on the 13.8KV.
 
Thank you for the usefull comments and links. I'll be checking them in detail.

Just for curiosity, does article 800.133 exists? If it does what does it say?

Thanks again.

Adrian.
 
Here it is:
800.133 Installation of Communications Wires, Cables, and Equipment.
Communications wires and cables from the protector to the equipment or, where no protector is required, communications wires and cables attached to the outside or inside of the building shall comply with 800.133(A) through 800.133(D).
(A) Separation from Other Conductors.
(1) In Raceways, Boxes, and Cables.
(a) Other Power-Limited Circuits. Communications cables shall be permitted in the same raceway or enclosure with cables of any of the following:
(1) Class 2 and Class 3 remote-control, signaling, and power-limited circuits in compliance with Article 725
(2) Power-limited fire alarm systems in compliance with Article 760
(3) Nonconductive and conductive optical fiber cables in compliance with Article 770
(4) Community antenna television and radio distribution systems in compliance with Article 820
(5) Low-power network-powered broadband communications circuits in compliance with Article 830
(b) Class 2 and Class 3 Circuits. Class 1 circuits shall not be run in the same cable with communications circuits. Class 2 and Class 3 circuit conductors shall be permitted in the same cable with communications circuits, in which case the Class 2 and Class 3 circuits shall be classified as communications circuits and shall meet the requirements of this article. The cables shall be listed as communications cables or multipurpose cables.
Exception: Cables constructed of individually listed Class 2, Class 3, and communications cables under a common jacket shall not be required to be classified as communications cable. The fire-resistance rating of the composite cable shall be determined by the performance of the composite cable.
(c) Electric Light, Power, Class 1, Non?Power-Limited Fire Alarm, and Medium Power Network-Powered Broadband Communications Circuits in Raceways, Compartments, and Boxes. Communications conductors shall not be placed in any raceway, compartment, outlet box, junction box, or similar fitting with conductors of electric light, power, Class 1, non?power-limited fire alarm, or medium power network-powered broadband communications circuits.
Exception No. 1: Where all of the conductors of electric light, power, Class 1, non?power-limited fire alarm, and medium power network-powered broadband communications circuits are separated from all of the conductors of communications circuits by a permanent barrier or listed divider.
Exception No. 2: Power conductors in outlet boxes, junction boxes, or similar fittings or compartments where such conductors are introduced solely for power supply to communications equipment. The power circuit conductors shall be routed within the enclosure to maintain a minimum of 6 mm (0.25 in.) separation from the communications circuit conductors.
Exception No. 3: As permitted by 620.36.
(2) Other Applications. Communications wires and cables shall be separated at least 50 mm (2 in.) from conductors of any electric light, power, Class 1, non?power-limited fire alarm, or medium power network-powered broadband communications circuits.
Exception No. 1: Where either (1) all of the conductors of the electric light, power, Class 1, non?power-limited fire alarm, and medium power network-powered broadband communications circuits are in a raceway or in metal-sheathed, metal-clad, nonmetallic-sheathed, Type AC, or Type UF cables, or (2) all of the conductors of communications circuits are encased in raceway.
Exception No. 2: Where the communications wires and cables are permanently separated from the conductors of electric light, power, Class 1, non?power-limited fire alarm, and medium power network-powered broadband communications circuits by a continuous and firmly fixed nonconductor, such as porcelain tubes or flexible tubing, in addition to the insulation on the wire.
(B) Cable Trays. Types CMP, CMR, CMG, and CM communications cables shall be permitted to be installed in cable trays. Communications raceways, as described in 800.179, shall be permitted to be installed in cable trays.
(C) Support of Conductors. Raceways shall be used for their intended purpose. Communications cables or wires shall not be strapped, taped, or attached by any means to the exterior of any conduit or raceway as a means of support.
Exception: Overhead (aerial) spans of communications cables or wires shall be permitted to be attached to the exterior of a raceway-type mast intended for the attachment and support of such conductors.
(D) Wiring in Ducts for Dust, Loose Stock, or Vapor Removal. Section 300.22(A) shall apply.
Click to expand...
 
All great answers. I didn't think about having 2 tray seperated.

Maybe I should have said why we are using cable tray because of just the many thiings we have to power up.

It is a build of tenant area. Suspended ceilings. 155 workstations out in this open area and plus adding offices and breakroom, conference room, etc.

My boss and I looked at it to quote the job and we were saying we are using cable tray. Then I alerted the E.E. here that we are using this - go and do research. I know how to lay it out.

I have B-Line's cable tray catalog (my E.E. printed it out for me) plus I have one on order.

Anyways - I couldn't exaclt understand the termology well enough to figure out data and telephone being ok or not okay (and the code article) in the code book being installed next to one another. But looking at the idea that rockyd suggested about 2 trays, that may be the way to go and then I don't have to worry about seperating, just running wire.

155 workstations with a required 3 outlets at each workstation. then you put at least 2 data phone at each workstation - you're talking about a lot of wire to run.

There is power poles specified for the worstations, and i plan to have the cable tray run in the suspended ceiling above these.

Now to go and figure out size of wire, how many wires, etc. that will ned to be pulled, especially when we normally don't do the telephone data wiring specification, but have to show the outlets and provide specs, if you know what I am talking about.

{edit : spelling mistakes}
 
Reading back through the thread...had to get my mind out of heavy industry zone, and try to think commercially creative. Sounds like a great project.

The only other solutions I thought might be helpful would be to consider some of the new "wire racks" that a lot of the computer places are big on (plenum rated wires?) that are considered cable trays.

Panduit (behind stations, etc) might be a way to create order considering your doing 155 stations!

Sounds like a fun project. Especially this time of year(indoors) in Minnesota.

My $.02 worth...hope it helps.
 
The engineer here printed off B Line Cable Tray which I have seen used in various places. It doesn't mean the electrical contractor can use something that is "as equal".

The main thing I am having fun with is actually drawing these things 3D and incorporting them with the HVAC and Plumbing. That's fun.

I took the suggestion of 2 feet inbetween the stacked cable trays.

I'm now trying to understand the types and smallest size of cable that you can run in a cable tray - and if you still have to run conduit as well. If you have to run conduit, would it make sense to use a cable tray then?

3 receptacles per workstation - 125 workstations. 20amp receptacles.
 
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