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Thread: Arc Flash Boundry

  1. #1
    Join Date
    Apr 2009
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    4

    Arc Flash Boundry

    I’ve read some of the articles and was hoping that some of you could shed some light on a disagreement with a co-worker about NFPA 70E. The co-worker was sent to troubleshoot a Bell & Gosset 480 Volt dual condensate motor/pump that was not running. He shut the (2) disconnects, placed the AoH switch to hand and the pumps did not start. He then opened the panel to verify o level voltage with a Fluke meter, upon verifying that no voltage existed he placed a lock on the disconnects. He performed this work with the following PPE; safety glasses, safety shoes, heavy duty pants, and long sleeve Nomex shirt.

    It is my interpretation that this is a violation based on the following;

    1) Even with the switch off until the voltage is verified you are suppose to
    assume that the voltage could be live.

    2) The 480V are still present at the top of the disconnect in the
    enclosure however not exposed.

    3) Opening a door or removing a cover could expose a worker to electrical
    hazards.

    4) PPE for flash protection must be worn any time you cross the Arc Flash
    boundary and "interact" with the equipment, weather the live parts are
    exposed or covered.

    5) He also violated the Prohibited Approach Boundary with his meter probe
    to verify voltage.

    6) Limited, Restricted and Prohibited have nothing to do with Arc Flash
    these are shock hazard boundaries only.




    My colleague contends that he did not violate NFPA 70E because of the following reasons;

    1) He is a qualified electrician and holds a E1 license.

    2) He is knowledgeable in the construction and operation of the equipment
    associated with the work task and he knew that the existing voltage
    was not exposed.

    3) With the disconnect in the off position there was no potential for Arc Flash.

    4) He did not violate Prohibited Approach Boundary~ 1 inch because of
    the design of the meter probe is insulated past the required 1 inch.

    5) Verifying voltage is not the same as testing for voltage.

    6) Because it was not intentional, and he did not knowingly violate the
    code.

    Could you please provide some clarity to the code issue?

  2. #2
    Join Date
    Apr 2009
    Location
    North Canton Ohio, two miles from the Akron Canton Airport
    Posts
    1

    NFPA 70E-2009 Establishing an Electrically Safe Work Condition...

    This is only part of the 70E requirements necessary to establish an electrically safe work condition. Suggest every employer train 70E to every employee, perform an arc flash hazard analysis, & properly label every electrical enclosure as required by OSHA. (ME)

    120.2(A) All electrical conductors & circuit parts shall not be considered to be in an electrically safe work condition until all of the applicable requirement of Article 120 have been met.

    120.1 Establishing an Electrically Safe Work Condition:
    An electronically safe work condition shall be achieved when performed in accordance with the procedures of 120.2 & verified by the following process:
    (1) Determine all possible sources of electrical supply to the specific equipment. Check applicable up-to-date drawings, diagrams, & identification tags.
    (2) After properly interrupting the load current, open the disconnecting devices(s) for each source.
    (3) Wherever possible, visually verify that all blades of the disconnecting devices are fully open or that drawout-type circuit breakers are withdrawn to the fully disconnected position.
    (4) Apply LOTO devices in accordance with a documented & established policy.
    (5) Use an adequately rated voltage detector to test each phase conductor or circuit part to verify they are deenergized. Test each phase conductor or circuit part both phase-to-phase & phase-to-ground. Before & after each test, determine that the voltage detector is operating satisfactory.

    Annex C.1.2.1
    Qualified Persons.
    Safe Approach Distance.
    Limits of Approach.
    Determine the Arc Flash Protection Boundary &, if the boundary is to be crossed, appropriate flash-flame protection equipment must be utilized.

    Annex C.1.2.4
    (5) Use PPE that is appropriate for working on exposed energized conductors or circuit parts & is rated for the voltage & energy level involved.

    Plane language: When performing Lockout/Tagout (LOTO), a Qualified Person must observe the instructions on the arc flash hazard warning label on the enclosure, take safety precautions, wear appropriate Personnel Protective Equipment (PPE):
    * Shock Hazard PPE (such as: gloves, leather gloves, dielectric overshoe, etc.)
    * Flame Retardant (FR) PPE over their entire body (FR clothing, leather shoes, Type E helmet, FR face shield w/ chin protection, balaclava, ear protection, eye protection, etc.)
    (ME)

  3. #3
    Join Date
    Feb 2005
    Location
    Charlotte, NC
    Posts
    6,381
    Quote Originally Posted by dippy View Post
    I’ve read some of the articles and was hoping that some of you could shed some light on a disagreement with a co-worker about NFPA 70E. The co-worker was sent to troubleshoot a Bell & Gosset 480 Volt dual condensate motor/pump that was not running. He shut the (2) disconnects, placed the AoH switch to hand and the pumps did not start. He then opened the panel to verify o level voltage with a Fluke meter, upon verifying that no voltage existed he placed a lock on the disconnects. He performed this work with the following PPE; safety glasses, safety shoes, heavy duty pants, and long sleeve Nomex shirt.
    First off there is no way we can tell you is this was correct or not without knowing what the Ei or if you are using the tables(And within the limits of the tables) What is your available fault current and clearing times?

    Quote Originally Posted by dippy View Post
    It is my interpretation that this is a violation based on the following;

    1) Even with the switch off until the voltage is verified you are suppose to
    assume that the voltage could be live.
    Correct
    Quote Originally Posted by dippy View Post
    2) The 480V are still present at the top of the disconnect in the
    enclosure however not exposed.
    Right, still an arc flash hazard
    Quote Originally Posted by dippy View Post
    3) Opening a door or removing a cover could expose a worker to electrical
    hazards.
    Right again, any interaction requires the correct arc flash PPE
    Quote Originally Posted by dippy View Post
    4) PPE for flash protection must be worn any time you cross the Arc Flash
    boundary and "interact" with the equipment, weather the live parts are
    exposed or covered.
    Right again
    Quote Originally Posted by dippy View Post
    5) He also violated the Prohibited Approach Boundary with his meter probe
    to verify voltage.
    No, you can cross the PAB with test probes as long as they are insulated, gaurded, and rated (CAT rating) for the type of system being checked. The PAB should no be crossed with a body part or conductive object.
    Quote Originally Posted by dippy View Post
    6) Limited, Restricted and Prohibited have nothing to do with Arc Flash
    these are shock hazard boundaries only.
    Back to being right again



    Quote Originally Posted by dippy View Post
    My colleague contends that he did not violate NFPA 70E because of the following reasons;

    1) He is a qualified electrician and holds a E1 license.
    Has nothing at all to do with being qualified per the NFPA 70E or OSHA.
    Quote Originally Posted by dippy View Post
    2) He is knowledgeable in the construction and operation of the equipment
    associated with the work task and he knew that the existing voltage
    was not exposed.
    Thats a good thing
    Quote Originally Posted by dippy View Post
    3) With the disconnect in the off position there was no potential for Arc Flash.
    Not until he proves it is de-energized with a live-dead-live test. Very straight foward about this in the 70E.
    Quote Originally Posted by dippy View Post
    4) He did not violate Prohibited Approach Boundary~ 1 inch because of
    the design of the meter probe is insulated past the required 1 inch.
    He is right there.
    Quote Originally Posted by dippy View Post
    5) Verifying voltage is not the same as testing for voltage.
    Well from a safe work practice standpoint they are the same thing.

    Quote Originally Posted by dippy View Post
    6) Because it was not intentional, and he did not knowingly violate the
    code.

    Could you please provide some clarity to the code issue?
    Last edited by charlie; 04-12-09 at 01:14 PM. Reason: Fixed the last quote.

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