Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Tray continuous ground conductor

Tray continuous ground conductor

Tray continuous ground conductor

Our contractor installed a multiconductor cable in a tray. I was told per NEC, we have to increase size of existing bare tray grounding cable because it's smaller than our newly installed cable equipment ground. Is that correct? Each cable in this tray has its own equipment ground.

RE: Tray continuous ground conductor

I am afraid the cable tray has to withstand the presumed short-circuit current. See NEC 2014 Art.250.96 A) Metal raceways, cable trays,etc.... ...with or without the use of supplementary equipment grounding conductors, shall be bonded where necessary to ensure electrical continuity and the capacity to conduct safely any fault current likely to be imposed on them.

RE: Tray continuous ground conductor

Per 250.96(A): " Cable trays.....that are to serve as equipment grounding conductors...". The cable tray in question is NOT to serve as equipment grounding conductor. Is there any other reference in the code that addresses this issue?

RE: Tray continuous ground conductor

I agree the cable tray does not have to be bonded but only connected to equipment grounding conductor. If this cable tray contains service cables it has to be grounded as per 250.80 Service Raceways and Enclosures.
250.86 Other Conductor Enclosures and Raceways means that any cable tray has to be connected to the equipment grounding conductor -excepting [see the 4 required exceptions for pos.1 exceptions and 2 or 3- if any ].
In this case only part of the ground fault current will flow through the cable tray. If you can appreciate how much will be this part you may verify if the cable tray will withstand this.
From our experience in power stations-we prefer to comply the code like all the current will flow through cable tray only.

RE: Tray continuous ground conductor

7anoter4, thanks for your reply. I still do not see the cable tray connection to grounding conductor requirement. This section you refer to (250.86) is for enclosures and raceways (conduits), not cable tray.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close