NEC 300.11(C): Cable tray used as a means of support

[cardoee]

Hi all,

First time poster, long time lurker. My search skills have failed me, so it's time for my first post:

NEC 300.11(C) states:

Raceways shall be used only as a means of support for other raceways, cables, or nonelectrical equipment under any of the following conditions:
(1) Where the raceway or means of support is identified as a means of support

My question is, what is the appropriate means of identifying the raceway as a support? In this particular instance, we're designing a greenfield compressor station & the mechanical engineers want to use the elevated cable tray as a support for some air piping. Do we only need to indicate that the cable tray is designed as a support in the drawings, or should there be physical signage upon installation as well?

As far as cable tray loads go, I do not yet have all my cables designed (still lacking load information), but will calculate all the cable weights per foot, plus the piping weights, and size per Eaton's B-Line catalog.

Any insight is appreciated, thanks.

 

[augie47]

Point of clarification: The air lines can not be installed IN the cable tray.
300.8 Installation of Conductors with Other Systems. Raceways
or cable trays containing electrical conductors shall not contain any pipe, tube, or equal for steam, water, air, gas, drainage, or any service other than electrical.
As far as being used as a support, in the past we have required engineering (P.E.) documentation.

 

[cardoee]

Thanks, for the response. I assume you mean the civil engineer will need to stamp a drawing indicating that the tray will be used as a support? I can stamp the electrical drawings with cable tray, but not sure how qualified I am to stamp for loading calcs (although I think it's a relatively easy calc).

Good clarification too. Confirmed: we will not be running the pipe in the cable tray... it will most likely run adjacent by means of unistrut.

 

[david]

Hi all,

First time poster, long time lurker. My search skills have failed me, so it's time for my first post:

NEC 300.11(C) states:

Raceways shall be used only as a means of support for other raceways, cables, or nonelectrical equipment under any of the following conditions:
(1) Where the raceway or means of support is identified as a means of support

My question is, what is the appropriate means of identifying the raceway as a support? In this particular instance, we're designing a greenfield compressor station & the mechanical engineers want to use the elevated cable tray as a support for some air piping. Do we only need to indicate that the cable tray is designed as a support in the drawings, or should there be physical signage upon installation as well?

As far as cable tray loads go, I do not yet have all my cables designed (still lacking load information), but will calculate all the cable weights per foot, plus the piping weights, and size per Eaton's B-Line catalog.

Any insight is appreciated, thanks.

I don’t know I f you want to make this distinction between raceways and support systems. 392.2

As you know listed, labeled and identified are defined in the NEC. See cable tray uses permitted 392.10

You mentioned identified, so you have to ask yourself identified by who or what specific allowance in the NEC or identification mark on the equipment

 

[cardoee]

I don’t know I f you want to make this distinction between raceways and support systems. 392.2

As you know listed, labeled and identified are defined in the NEC. See cable tray uses permitted 392.10

You mentioned identified, so you have to ask yourself identified by who or what specific allowance in the NEC or identification mark on the equipment

Thank you david. You caused me to revisit the definitions for "identified", "equipment", & "raceway". NEC explicitly says that cable trays are support structures and are not raceways. Not sure why I categorized them as raceways in my head, but it's good to revisit the basics periodically.

I'll consider my question answered, thank you both for the input.