User Tag List

Results 1 to 10 of 10

Thread: NFPA 70E compliance- automation programmimg engineers

  1. #1
    Join Date
    Jun 2019
    Location
    Louisiana
    Posts
    5
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    NFPA 70E compliance- automation programmimg engineers

    What level of Arc Flash and Shock PPE are Automation Engineers required to wear when trouble shooting a PLC with a live <120VAC?

  2. #2
    Join Date
    Jun 2019
    Location
    Louisiana
    Posts
    5
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Arc Flash PPE for <120VAC

    What level Arch Flash and Shock PPE is required when trouble shooting a PLC, VFD or MCC with live <120VAC?

  3. #3
    Join Date
    Jul 2006
    Location
    San Francisco Bay Area, CA, USA
    Posts
    8,862
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Assuming no line voltage equipment in the panel, you would not need anything (No PPE Required) if you use the "Task Tables", because it falls under this rule:
    Working on control circuits with
    exposed energized electrical
    conductors and circuit parts,
    nominal 125 volts ac or dc,
    or below without any other
    exposed energized equipment
    over nominal 125 volts ac or
    dc, including opening of hinged
    covers to gain access.
    I personally use common sense precautions; long sleeve cotton shirt and safety glasses, because I've seen too many things happen.
    __________________________________________________ ____________________________
    Many people are shocked when they discover I am not a good electrician...

  4. #4
    Join Date
    Mar 2013
    Location
    Rutland, VT, USA
    Posts
    382
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Is the highest voltage in the area you are working 120V? I ask since you mention MCC and they are typically 480V. Are you in a cubicle where the 480V breaker is?

    If only 120V, then you need non-melting clothing (cotton), safety glasses, Class 00 gloves plus the training. You should also be doing a hazard and risk analysis for the task you are performing

  5. #5
    Join Date
    Jun 2019
    Location
    Louisiana
    Posts
    5
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    NFPA 70E compliance- automation programmimg engineers

    Thanks for answering so quickly. I'm told that typically there's a 480VAC in the same PLC panel box. The 480VAC should be LOTO, which is why my only concern is the live 120VAC. I just hired an Electrical Safety trainer/consultant to train our guys in NFPA 70E. He's telling us that our guys need to at least have FR clothing, safety glasses and rubber gloves/leather outers (00), to open the panel and use voltmeter / trouble shoot the 120VAC. Where can I find the information you cited?

  6. #6
    Join Date
    Jun 2019
    Location
    Louisiana
    Posts
    5
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Arc Flash PPE for <120VAC

    Thanks for answering so quickly. I'm told that typically there's a 480VAC in the same PLC panel box. The 480VAC should be LOTO, which is why my only concern in the PLC is the live 120VAC.
    I recently hired an electrical safety trainer/consultant to train our guys in NFPA70E. He's telling us pretty much the same as you just said; FR clothing, safety glasses and rubber gloves (00) with leather outers to open the panel and use a voltmeter and trouble shoot the live 120VAC.

    Does the 480V need to be live when trouble shooting a MCC?

  7. #7
    Join Date
    Jun 2019
    Location
    Louisiana
    Posts
    5
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    NFPA 70E compliance- automation programmimg engineers

    Jraef - I found the task table quote you mentioned. Thank you. So basically, my guys need to be protected from "shock" at 120VAC-live, rather than an Arc Flash. Correct?

  8. #8
    Join Date
    Jul 2006
    Location
    San Francisco Bay Area, CA, USA
    Posts
    8,862
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Please don't cross post. I am closing the other thread because this probably belongs here.

    In the original thread you didn't mention the MCC or VFD, that makes a difference. Locking off the breaker / disconnect of a panel does NOT make it totally safe to be in it without PPE, so long as the LINE SIDE of the equipment is sharing the same space. So in an MCC bucket, if you only lock off the UNIT disconnect, it doesn't qualify as not needing PPE if the REST of the MCC is still live, because an arc flash event elsewhere could still propagate the plasma and blast pressure right into your face; the bus bar barriers are NOT intended to withstand that. The only way to avoid having to wear PPE to work on an MCC bucket is to power down the ENTIRE MCC, or to remove the bucket and work on it on the bench. The same is true in a VFD enclosure; a dropped tool or insulation failure on the line side of the disconnect would still have you exposed to the dangers (I personally have lived through that one, but I was lucky). So that's why I had qualified my earlier statement to say IF THERE IS NO LINE VOLTAGE, you don't need PPE. that is NOT the case of there are line power devices and the line power is still hot anywhere in the panel.
    Last edited by Jraef; 06-03-19 at 08:00 PM.
    __________________________________________________ ____________________________
    Many people are shocked when they discover I am not a good electrician...

  9. #9
    Join Date
    May 2019
    Location
    oklahoma
    Posts
    9
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    NFPA 70E 130.7(C)(15)(A)(b) Table

    According to this table under equipment rated 240v and below you need a Arc Flash PPE Category 1. Arc Flash Boundary 19in.

    if you go to Table 130.7(C)(16) you will see what type of Clothing and PPE you are required as Category 1 on the previous table.

  10. #10
    Join Date
    Mar 2013
    Location
    Rutland, VT, USA
    Posts
    382
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by jctj88 View Post
    According to this table under equipment rated 240v and below you need a Arc Flash PPE Category 1. Arc Flash Boundary 19in.

    if you go to Table 130.7(C)(16) you will see what type of Clothing and PPE you are required as Category 1 on the previous table.
    NFPA 70E-2018 is Table 130.7(C)(15)(a) which lists Category 1 for equipment rated 240V and below as long as the parameters of maximum available fault current is no greater than 25kA and the maximum clearing time is 2 cycles (0.03 sec) are met. So the OP would have to obtain the available, not infinite bus, fault current from the utility and model the system to the equipment to obtain the available fault current and then obtain the time current curve for the protective device upstream from that equipment to determine if it will trip in 2 cycles or less.

    You need to pay attention to the parameters of the table to use the table method.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •