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 Post subject: Requiring PPE for racking breakers
PostPosted: Thu Oct 01, 2020 6:56 am 

Joined: Mon Mar 09, 2020 9:27 am
Posts: 6
Can someone help me understand and relay the reasoning behind needing arc flash PPE when racking breakers in an MCC? The argument was that if the door needs to be open when racking the breaker it is obvious why you need PPE. If the door can remain closed and a breaker racked in via a small racking port, why do you need PPE when you could close the breaker without any PPE? We were just going by the table in 130.6.


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 Post subject: Re: Requiring PPE for racking breakers
PostPosted: Fri Oct 02, 2020 5:35 am 

Joined: Thu Apr 18, 2019 11:42 am
Posts: 41
I would say it's due to additional risk. As you know, the tables are risk based. For example, there is a higher risk for racking/unracking because of operator error. It is/has been the case where breakers are racked in to their final position in the closed position, drawing and arc, and...well you know the rest.

Mike


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 Post subject: Re: Requiring PPE for racking breakers
PostPosted: Fri Oct 02, 2020 3:14 pm 
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Joined: Mon Sep 17, 2007 5:00 pm
Posts: 1561
Location: Scottsdale, Arizona
If an arc flash occurs, the doors may not remain closed and even if they do, energy can still be released through any hole, vent etc. The link is to a video where I have 2 arc flash tests. The second one is 18,000 amps and it blows the door open. Hope it helps give you better feel for what happens.

VIDEO: Doors Blowing Open


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 Post subject: Re: Requiring PPE for racking breakers
PostPosted: Mon Oct 05, 2020 7:15 am 
Arc Level

Joined: Tue Jan 13, 2009 5:00 pm
Posts: 542
Why not implement remote racking from outside the boundary?


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 Post subject: Re: Requiring PPE for racking breakers
PostPosted: Mon Oct 05, 2020 9:14 am 
Sparks Level

Joined: Tue Jan 19, 2010 2:35 pm
Posts: 146
Yes, you wear PPE to do this process. If you watched Jim's video, you saw that the doors don't necessarily stay closed and keep an arc flash contained. How a latched door can open is another question, but they do fly open.
The question I have is how often do you do this process? Seems like racking a breaker in or out of a MCC is not a standard process. If you do this on a regular basis, I'd want to know why and is it really so important?


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 Post subject: Re: Requiring PPE for racking breakers
PostPosted: Tue Oct 06, 2020 4:06 pm 
Arc Level

Joined: Tue Jan 13, 2009 5:00 pm
Posts: 542
stevenal wrote:
Why not implement remote racking from outside the boundary?

https://www.eaton.com/us/en-us/products/medium-voltage-power-distribution-control-systems/switchgear/remote-racking-and-control-options-for-metal-clad-switchgear.html


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 Post subject: Re: Requiring PPE for racking breakers
PostPosted: Mon Nov 09, 2020 7:41 am 
Sparks Level

Joined: Sun Sep 23, 2007 5:00 pm
Posts: 127
Location: Calgary, Alberta, Canada
For clarity the work task is racking a power circuit breaker in or out of switchgear, not an MCC.

Follow a procedure, turn off the load following normal procedures. Line side is energized. Open door racking is recommended as if there is any pressure it will be reduced.

Before the work task is executed, has your employer completed a risk assessment procedure for the work task? The RAP will include the work task's shock risk assessment and arc flash risk assessment with the outcome determining additional protective measures.

The overall Job and individual work task's risk assessment includes a review of the potential injury or damage to health and likelihood of occurrence to determine the hierarchy of risk control methods to apply to eliminate exposure or reduce risk to as low as reasonably practicable.

All of this would be in the employer's documented, implemented and audited Electrical Safety Program.


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