×
Follow Us
Results 1 to 1 of 1

PADMOUNT TRANSFORMER ARC FLASH

    #1
  1. RedBrick's Avatar
    RedBrick is offline Junior Member Pro Subscriber
    Join Date
    Dec 2019
    Posts
    14
    Reputation

    PADMOUNT TRANSFORMER ARC FLASH

    I've had this question about padmount transformer arc flash protection for awhile and I haven't had anyone able to answer the question. Here it is....

    Typically anytime you are working on the secondary side of a transformer, and more specifically for my question a padmount transformer, there is a large amount of incident energy available and therefore the arc flash boundary is fairly large. If you are tasked with verifying the absence of voltage at a padmount transformer with a 480v secondary you will have to open the door to the secondary which exposes you to the exposed parts of the secondary terminations.

    NFPA 70E 120.2 (A) says "Electrical conductors and circuit parts shall not be considered to be in an electrically safe work condition until all of the requirements of Article 120 have been met."

    NFPA 70E Table 130.5 (C) Estimate of Likelihood of Occurrence of Arc Flash Incident

    - This table list the likelihood of an occurrence of an arc flash as "yes" for two applicable scenarios when working on a padmount transformer:

    1. Opening hinged doors or covers to or removal of bolted covers (to expose bare, energized electrical conductors and circuit parts).

    2. Application of temporary protective grounding equipment, after voltage test.

    Depending on the transformer's incident energy a 40 cal, 65 cal, or even greater PPE would not be sufficient.
    Some would say go downstream of this transformer and check on the load side of an overcurrent protection device and then return to the transformer to install the personal protective grounds. Even then you still can't be sure that the conductors are de-energized.

    Ultimately the question is how can you work safely on the secondary side of a transformer to verify the absence of voltage when the arc flash boundary could possibly be 10'+?

    Any thoughts/insights and experience on this would be appreciated. Thanks.

Subscribe

Share this thread

Related Topics

  1. Always check the arc flash rating sticker
    By romeroduke in forum Safety and Arc Flash Talk
    Replies: 12
    Last Post: January 31, 2021, 10:24 AM
  2. Schrader valve size for Padmount Transformer
    By phasor in forum Electrical Testing Talk
    Replies: 4
    Last Post: August 4, 2019, 03:57 PM
  3. Layering Arc Flash Clothing, Is It Acceptable?
    By SecondGen in forum Safety and Arc Flash Talk
    Replies: 1
    Last Post: May 20, 2018, 07:53 AM
  4. Arc Flash Tables vs Arc Flash Studies
    By mnmurphy in forum Safety and Arc Flash Talk
    Replies: 0
    Last Post: March 26, 2015, 09:40 PM

Tags for this Thread

Follow us


Explore TestGuy


NETA Certification Training


NICET Electrical Power Testing


Help and Support




You are viewing the archives. Enjoy new features and join the conversation at wiki.testguy.net