×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Jobs

Sputtering System Grounding

Sputtering System Grounding

Sputtering System Grounding

(OP)
I am working on a project where we are installing a sputtering system. The manufacturer is calling for us to drive (2) new ground rods (not bonded to the building ground electrode system) to ground the vacuum chamber. This ground will be in addition to a safety ground coming from the panelboard to the sputtering system power supply. At first I thought this additional ground electrode had to be bonded to the building's ground electrodes; however, people are quoting NEC article 250.54, Auxiliary ground electrodes, and saying this allows the ground rods to be NEC compliant. After doing some research it appears this article will allow this installation (even though most of the information found online makes me think this article is to allow ground rods at remote light poles). Is this installation NEC compliant?

The most important question of all: Even if this installation is NEC compliant, is it a good idea? Wouldn't any ground faults, lightning strikes, etc. cause a potential difference between the two ground systems which could cause issues?

DJR

RE: Sputtering System Grounding

Code, articles or whatever. Physics says you are right. But, then again, you are in TT territory (I think) and that's where anything can happen.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: Sputtering System Grounding

250.54 allows extra ground rods to be connected to the equipment grounding conductor, not just to the equipment. The difference between this and a normal grounding electrode is that you don't have to comply with the bonding requirements to the grounding electrode system. The auxiliary rod is still connected to the grounding electrode system through the equipment grounding conductor.

That being said, if the auxiliary ground rod is connected to the vacuum chamber ground, and the equipment grounding conductor is connected to the vacuum chamber ground, then the auxiliary ground rod is connected to the equipment grounding conductor. If somehow, there are two independent equipment ground points, then it would not be NEC compliant to connect one of them only to the auxiliary ground rod. This would use the earth as a ground-fault return path which doesn't comply with 250.54.

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!


Resources