mixing data, ac and dc cables in a wireway

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mestudentinva

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Hello, I'm working as an engineering intern at an industrial plant and we've been tasked to help spot potential NEC problems and bring them up to our managers - they are also doing their own audits but they just use us for an extra set of eyes and to keep us busy..

i think i found a couple but i can't seem to find anything in the NEC 70. There is a wire cable tray about 4" wide, 2" deep and 100' long - it carries 480Vac cables, 24 vdc cables and data cables (coaxial controlnet cables) all next to each other. the tray is coverred with a metallic lid and clips. the tray is located 4' off the finished floor running next to an industrual machine (i'm being vague on purpose).

it seems unsafe to me.. if you weren't careful or didn't know the tray well - you could vey easyily be playing with a 480 vac wire and not know it. My question is... are there any rules about mixing data and power cables? if not are there any rules of thumb about this? how about using the wireway itself - I assume it must be grounded - but other than that is it a legit way to carry these wires?

Thanks for your help.
 
Since they're all cables I don't see a code issue. There may be a performance issue given their proximity to each other.
 
thanks

thanks

ahhh.. so in my case all the insulation on all the cables in the tray must be insulation rating for 480V right?

(C) Conductors of Different Systems.
(1) 600 Volts, Nominal, or Less. Conductors of ac and dc
circuits, rated 600 volts, nominal, or less, shall be permitted
to occupy the same equipment wiring enclosure, cable, or
raceway. All conductors shall have an insulation rating
equal to at least the maximum circuit voltage applied to any
conductor within the enclosure, cable, or raceway.
 
If this is the same "wireway" you describe in this post:

http://forums.mikeholt.com/showthread.php?t=98259

then the above described assembly is a raceway according to the definition in Art. 100 and falls under 300.3 (c)(1)


I was surprised to learn that a cable tray isn't considered a raceway or wiring enclosure or 'something'...
 
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jerm said:
Interesting. Bob, how do we find out if this tray is listed as suitable for grounding? (see other thread...)
Click to expand...

250.118(11)

But take a look at 344.2 or 348.2 or any of the .2s in a raceway Article, now compare those to 392.2.
 
I'm lost.

I'm lost.

I thought for sure supply wiring could NOT share the same raceway as CATV and the such, why is that not considered in a trough? Maybe I had the wrong teacher. Teacher or not, that is a practice I would never allow.
Can someone please explain in depth????
Wire tray not a raceway?? I am so confused.
See my signature?
 
Since you say the cable tray has a metallic lid and clips, therefore it is enclosed, it should be considered a wireway or a raceway.

300.3(c)(1) requires your ControlNet cable insulation to be rated for the 480V. Since ControlNet cable is a coax cable used for communications, your cable probably does not have the rating necessary to be in that wireway/raceway. A large number of coax cables are only rated at 300V.

If your specific use of the ControlNet communications protocol is for PLC control of industrial machinery or safety related circuits, there might be some other issues related to this installation.
 
KentAT said:
Since you say the cable tray has a metallic lid and clips, therefore it is enclosed, it should be considered a wireway or a raceway.
Click to expand...

The NEC does not define cabletray as a raceway, it is a support system.

Check out 392.2
 
Thanks, iwire. I think the OP needs clarifying.

mestudentinva:

Please specify the type of your equipment. The manufacturer's designation is probably what counts.

Is is a wireway, as mentioned in your title? If so, then it is also a raceway.
Is it a cable tray?

Raceway. An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways. (Article 100, definitions)

Metal Wireways. Sheet metal troughs with hinged or removable covers for housing and protecting electrical wires and cable and in which conductors are laid in place after the wireway has been installed as a complete system. (376.2)

Cable Tray System. A unit or assembly of units or sections and associated fittings forming a structural system used to securely fasten or support cables and raceways. (392.2) Scope is: This article covers cable tray systems, including ladder, ventilated trough, ventilated channel, solid bottom, and other similar structures. (392.1)
 
392.9(A) seems to explicitly permit any combination of power, lighting, control and signaling conductors. Apparently without respect to cable insulation.

I've looked all over the place for required clearances and/or barriers between power and lighting and class 2, class 3, communications circuits, etc. in cable trays and come up short.
 
ike5547 said:
392.9(A) seems to explicitly permit any combination of power, lighting, control and signaling conductors. Apparently without respect to cable insulation.

I've looked all over the place for required clearances and/or barriers between power and lighting and class 2, class 3, communications circuits, etc. in cable trays and come up short.
Click to expand...


See 725.55 (A) thru (J), 2005 NEC for requirements for "Separation from Electric Light, Power, Class 1, Non?Power-Limited Fire Alarm Circuit Conductors, and Medium Power Network-Powered Broadband Communications Cables. " of Class 2 and 3 circuits in a cable tray. The 2008 NEC renumbers this section and has additional info.
 
KentAT said:
See 725.55 (A) thru (J), 2005 NEC for requirements for "Separation from Electric Light, Power, Class 1, Non?Power-Limited Fire Alarm Circuit Conductors, and Medium Power Network-Powered Broadband Communications Cables. " of Class 2 and 3 circuits in a cable tray. The 2008 NEC renumbers this section and has additional info.
Click to expand...

Thank you.

This is what the OP should be looking at.
 
KentAT said:
See 725.55 (A) thru (J), 2005 NEC for requirements for "Separation from Electric Light, Power, Class 1, Non?Power-Limited Fire Alarm Circuit Conductors, and Medium Power Network-Powered Broadband Communications Cables. " of Class 2 and 3 circuits in a cable tray. The 2008 NEC renumbers this section and has additional info.
Click to expand...

KentAT, that section applies only to individual conductors, not cables.

You can place both power cables and communication cables in the same cable tray without any barrier or separation.
 
ike5547 said:
I've looked all over the place for required clearances and/or barriers between power and lighting and class 2, class 3, communications circuits, etc. in cable trays and come up short.
Click to expand...

You will not find one because as long as each system is contained in it's own cable assembly there is no clearance and/or barrier requirement.
 
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