It is currently Tue Jun 02, 2020 5:08 pm



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: PPE required in de-energized panel with Live supply side?
PostPosted: Mon Sep 12, 2011 6:27 am 

Joined: Thu Feb 24, 2011 3:36 am
Posts: 13
Hello All,

I believe I posted a similar question a while back but never got a clear answer.

Does an employee have to wear PPE when working in a panel that is verified to be de-energized, but has a live guarded supply side? Guarded supply side prevents accidental contact of the employee or conductive objects with energized parts. I am particularly concerned about my panels that are classified as HRC 1 and 2.

OSHA interpretation says:

Question 2: Does the employee need to wear full flame-resistant (FR) clothing, head and face protection, and rubber insulating gloves when working on a panel that has been completely de-energized, either disconnecting and locking out the panel itself or by disconnecting and locking out a panel upstream from the panel where the work is being performed?

Answer: No. If there are no exposed energized electrical components after a person has locked and tagged out the disconnect, and verified de-energization, per the requirements of §1910.333(b)(2), then there would be no potential for electric shock or arc flash. The protective equipment that you mentioned would not be required.3 However, personal protective equipment may be required by another condition independent of electrical hazards. For example, if an employee is working in the panel box and using a drill or saw that is creating flying particles, or if the employee is using a chemical that presents a splash hazard to the eyes, the eye and/or face protection may be required.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=25438

I am getting caught up on where it says "completely de-energized" in the question. From my knowledge locking out the panel itself does not completely de-energize the panel as there is still energy going to the supply side.

So, can I tell my guys that they do not need PPE when working in a panel that is locked out with a live guarded supply side?

Thanks for the help
Hope I am clear with my question


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Sep 12, 2011 10:33 am 
Sparks Level

Joined: Sat May 17, 2008 5:00 pm
Posts: 85
runner wrote:
OSHA interpretation says:

Question 2: Does the employee need to wear full flame-resistant (FR) clothing, head and face protection, and rubber insulating gloves when working on a panel that has been completely de-energized, either disconnecting and locking out the panel itself or by disconnecting and locking out a panel upstream from the panel where the work is being performed?

Answer: No. If there are no exposed energized electrical components after a person has locked and tagged out the disconnect, and verified de-energization, per the requirements of §1910.333(b)(2), then there would be no potential for electric shock or arc flash.


Wow, this would shed a diffferent light on a lot discussions previously on the forum.

Using this logic would change the answer about having a plexi-glass or some other barrier or cover over energized conductors to eliminate the arc flash hazard. There would not be "exposed energized electrical components" This seems to indicate there is not a hazard in that case. I find it hard to believe that is what they meant. Did I miss something? This seems to contradict what a lot of people are thinking (me included).


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Sep 12, 2011 11:57 am 
Arc Level

Joined: Wed Jun 04, 2008 9:17 am
Posts: 428
Location: Spartanburg, South Carolina
K. Engholm wrote:
Wow, this would shed a diffferent light on a lot discussions previously on the forum.

Using this logic would change the answer about having a plexi-glass or some other barrier or cover over energized conductors to eliminate the arc flash hazard. There would not be "exposed energized electrical components" This seems to indicate there is not a hazard in that case. I find it hard to believe that is what they meant. Did I miss something? This seems to contradict what a lot of people are thinking (me included).

If the source side of the disconnect is guarded from contact, and the panel has been verified to be de-energized, what is the interaction that would present an arc hazard risk? You won't be interacting with the disconnect while working on the panel. This is not the same as working on an energized panel where an arc might occur in the panel and travel to the source side of a main breaker where the incident energy is higher.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Sep 12, 2011 4:32 pm 

Joined: Wed Jan 26, 2011 12:04 pm
Posts: 32
jghrist wrote:
... what is the interaction that would present an arc hazard risk? You won't be interacting with the disconnect while working on the panel...


I think jghrist's statement above actually turns into the appropriate question. If there will, in fact, be interaction of any kind (working on lugs or any kind of physical interaction), one could conclude that an arc flash is possible even on shock-protected components. We just ran into this in switchgear where the compartmentalization was rugged but not arc-resistant. On paper, there was nothing hot in the compartment being worked in, but 18" on the other side of the interior wall, there was. We simply risk assessed it and went with the higher protection, but I think the situation can dictate that. As many will agree, this also has a "doors-open/doors-closed" element to it.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Mon Sep 12, 2011 4:47 pm 
Sparks Level

Joined: Sat May 17, 2008 5:00 pm
Posts: 85
This might be a stretch but based on today's discussion, could a panel manufacturer simply have some shroud or other shield over the incoming main device's line side lugs? Then once we have de-energized and verified everything below the main line side lugs is safe, we don't have to worry about the main?

I see this as being huge when it comes to panels on the immediate secondary side of transformers where Ei becomes quite high due to reliance on the transformer primary device.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Sep 13, 2011 5:56 am 
Sparks Level

Joined: Wed May 13, 2009 3:19 pm
Posts: 56
twm22 wrote:
On paper, there was nothing hot in the compartment being worked in, but 18" on the other side of the interior wall, there was. We simply risk assessed it and went with the higher protection...


What risks did you identify if the energized bus was behind the interior panel? It does not sound like any of your activities would have resulted in creating an arc event (unless you were just in the wrong place at the wrong time); just wondering why you all when with the higher PPE.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Sep 13, 2011 5:17 pm 

Joined: Wed Jan 26, 2011 12:04 pm
Posts: 32
SCGEng1 wrote:
What risks did you identify if the energized bus was behind the interior panel? It does not sound like any of your activities would have resulted in creating an arc event (unless you were just in the wrong place at the wrong time); just wondering why you all when with the higher PPE.


Boring into the concrete deck with high vibration expected. Job hasn't been done yet - we're still considering how to get it done and might not go with the higher PPE, but our original assessment pointed in that direction


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Sep 14, 2011 5:43 am 
Sparks Level

Joined: Wed Oct 29, 2008 6:06 am
Posts: 136
Location: Michigan
K. Engholm wrote:
Using this logic would change the answer about having a plexi-glass or some other barrier or cover over energized conductors to eliminate the arc flash hazard. There would not be "exposed energized electrical components" This seems to indicate there is not a hazard in that case. I find it hard to believe that is what they meant. Did I miss something? This seems to contradict what a lot of people are thinking (me included).


The letter is talking about working in a panel that has been de-energized, locked out and properly verified as such with a meter but still has voltage on only the line side of the main. If the line side of the main provides adequate employee protection through guarding which prevents accidental contact of the employee or conductive objects then it may be considered de-energized. So the logic is if the panel is considered de-energized ergo no arc flash hazard.

Using plexi-glass to cover exposed energized parts in a LIVE panel that has not been locked out is not the same as the situation being discussed in the letter. In such a case we consider the person protected from electric shock but not arc flash.

We went back to the manufacturer of the disconnects used in the majority of our panels and inquired about a solution. They gave us the following attachment and we've replaced the line side terminal guard that initially came with the disconnect with these.


You do not have the required permissions to view the files attached to this post.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Sep 14, 2011 8:17 am 

Joined: Tue May 18, 2010 8:20 am
Posts: 5
Location: Indianapolis, IN
The question posed to the forum is significantly different from the question posed to OSHA. The question to OSHA states "completely de-energized" while the question posed to the forum states "live guarded line".


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Wed Sep 14, 2011 7:00 pm 
Sparks Level

Joined: Sat May 17, 2008 5:00 pm
Posts: 85
Barrusr wrote:
The question posed to the forum is significantly different from the question posed to OSHA. The question to OSHA states "completely de-energized" while the question posed to the forum states "live guarded line".

Exactly! I appreciate everyone's comments and clarifications but "completely de-energized" jumped out at me too.


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Thu Sep 15, 2011 6:42 am 

Joined: Thu Feb 24, 2011 3:36 am
Posts: 13
Where it says "been completely de-energized, either by disconnecting and locking out the panel itself or..." in the question posed to OSHA isn't there still energy going into the panel when you disconnect and lock out at the panel itself?


Question posed to OSHA
Question 2: Does the employee need to wear full flame-resistant (FR) clothing, head and face protection, and rubber insulating gloves when working on a panel that has been completely de-energized, either disconnecting and locking out the panel itself or by disconnecting and locking out a panel upstream from the panel where the work is being performed?


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Nov 01, 2011 7:05 pm 

Joined: Tue Nov 01, 2011 5:40 pm
Posts: 8
It seems your forgetting a few things. First of all there are other things that can cause that energized line side to arc flash which might not have anything to do with the work your doing or from any type of contact, the potential hazard is still there. Second, if it does arc, is it completely shielded from releasing heat into the work area? The biggest question I belive in this situation would be, Are you doing work within the Arc Flash Protection Boundary? (I see many control cabinets where there is only 120V in one section way outside the FPB of the 480V elements).


Top
 Profile Send private message  
Reply with quote  
 Post subject:
PostPosted: Tue Nov 08, 2011 8:44 am 

Joined: Thu Oct 27, 2011 9:34 am
Posts: 14
I would push you back to jgrhist's post. In the previous post I would ask that if you were painting the floor in front of this panel would you be in the Arc Flash Protection Boundary? The answer is no because you are not "interacting" with equipment specifically even though you are painting inches from it. If it is completely guarded and in no way are you "interacting" with any part of the live equipment or enclosure then there should not be an issue.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

All times are UTC - 7 hours


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
© 2019 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883