Cable tray ground bonding

[brother]

I was in a discussion with a friend, and the way they do the low votage cable from the (data phone etc) cable tray is fish flex down the wall of the existing places and mount a cut in box. Then they would run more conduit (emt) to the tray and bond to there.

I told him that 'technically' when they do bonding of the tray to the conduit that they are suppose to run a ground wire inside the conduit because the flex cannot be used as a grounding means as per 2005 NEC 250.118 because the 'flexibilty was necessary' when fished down the wall or if the total run is over six feet of flex in the whole run even though i've seen it done alot.

I reread 250.118 (7) myself and aparrently there is not same restriction as when 'flexiblity is necessary' as with 250.118 (5) and (6). I wonder why??

Also I was wondering about when the conduit (emt) is just stubbed up out of the wall with a bushing on the end and cable is ran from the tray a good distance without conduit and then down the stubb in the wall, does that stub 'technically' have to be bonded as well?? I have always seen it not done since it was just a stub. Thanks for the help just trying to get a better understanding.

 

[brother]

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[RB1]

If the low voltage system is not required to be grounded by Part II, or Part VIII of Article 250, the conduit stubs and cable tray are not required to be grounded. Reference Section 250.112(I).

 

[brother]

If the low voltage system is not required to be grounded by Part II, or Part VIII of Article 250, the conduit stubs and cable tray are not required to be grounded. Reference Section 250.112(I).

Ok, but its my understanding that the cable tray would be required to be bonded. I read your reference section.

So where are my 'experts' on this stuff. Love to hear from others.