Bonding Metallic Cabletray for use with non-power conductors

[RFLahamGouSqhsT]

Hello all,

First time posting to this forum.

I'm an old guy studying for the TX journeyman exam ( currently licensed Master and Journeyman in MA since 1991, Journeyman in MT since 2024) and I'm stumped as to how to size the bonding jumper for non-continuous sections of metallic cable tray used for non-power conductors. 392.60(A) says cable tray shall be electrically continuous through approved connections or use of a bonding jumper. As these cables are non-power type it would appear the references in 392.60(A) to 250.96 and and 250.102 would not apply- no OC Protection. Also the words 'if necessary' appear in 250.96(A) relating to whether the cable tray requires bonding, (a condition presumably determined by an engineer?) although in my question I would not have the need for the cable tray serve as an equipment grounding conductor. I've considered Table 250.102(C)(1) and Table 250.122 but neither seems to fit the bill. Articles 700 and 800 don't specify for bonding jumpers as far as I can tell.

In all the years I've installed miles of cable trays for non-power conductors ( data-comm, fiber optic, etc.) the bonding jumper has been #6 or #4 copper as specified on E or TC plans however I can't seem to find where that sizing is determined in the 2023 NEC. I never felt the need to check what was spec'd on the plans since AHJs never questioned it.

Anyone out there know the answer to this?

Thanks for the help.

 

[roger]

The last sentence of 392.60(A) in older codes specified it as not smaller than #10, I don't know why they removed it.



392.60 Grounding and Bonding.
(A) Metallic Cable Trays. Metallic cable trays shall be
permitted to be used as equipment grounding conductors
where continuous maintenance and supervision ensure that
qualified persons service the installed cable tray system and
the cable tray complies with provisions of this section. Metallic
cable trays that support electrical conductors shall be
grounded as required for conductor enclosures in accordance
with 250.96 and Part IV of Article 250. Metal cable
trays containing only non-power conductors shall be electrically
continuous through approved connections or the use
of a bonding jumper not smaller than a 10 AWG.