It is currently Tue Dec 12, 2017 10:19 pm



Post new topic Reply to topic
Author Message
ekstra   ara
 Post subject: PPE when connecting remote racking devices
PostPosted: Wed Oct 04, 2017 10:04 am 
Offline

Joined: Mon May 21, 2012 5:00 pm
Posts: 8
I was interested if anyone had an opinion on what PPE (if any) would be necessary when connecting a remote racking device to a breaker. If the breaker is out and shutters closed, I don't see any hazard. If the breaker is deenergized, but still racked in to the cubicle, there could be a potential for a hazard, however is just the act of installing a remote racking device considered "interacting"?


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: PPE when connecting remote racking devices
PostPosted: Thu Oct 05, 2017 4:32 am 
Offline
Plasma Level
User avatar

Joined: Tue Oct 26, 2010 9:08 am
Posts: 1820
Location: North Carolina
H2Pitt wrote:
I was interested if anyone had an opinion on what PPE (if any) would be necessary when connecting a remote racking device to a breaker. If the breaker is out and shutters closed, I don't see any hazard. If the breaker is deenergized, but still racked in to the cubicle, there could be a potential for a hazard, however is just the act of installing a remote racking device considered "interacting"?


The phrase is interacting in such a way that it could cause an arc. How is fiddling with a handle that you have to rotate but not rotating it going to cause an arc? Further there might be an exception but on every drawout breaker I've worked with/on, the front just has controls. With some such as the old Westinghouse ones with the pivoting door there is physically no access to any of the power conductors whatsoever. With say for instance a GE Powerbreak breaker you have access and can at least theoretically reach around to the stabs but you'd have to make a serious (deathwish) effort to do so. Other words such as inadvertent or accidental come into play here...is the proposed interacting possible to occur inadvertently?

Keep in mind that the definition of an arc flash in 70E has a basic notion of LIMITED likelihood. If we approach electrical equipment in an absolute likelihood point of view, this causes numerous problems. The first is that electrical equipment is no longer safe to operate or even be in the same room with it because somehow, someway some crazy unlikely situation can occur. This is also true of ALL industrial equipment. Second the point is to maintain a likelihood that is not any different from other similar sources of injury in the work place. We don't erect meteor barriers over parking lots and walkways outside for instance even though falling meteors have the exact same outcome if someone is struck by one (severe injury or death) because the likelihood is very low. Most standards and literature of comparable accident statistics puts the likelihood at around 1 in 10,000 to 1 in 1,000,000 as a target depending on the industry and how the number is arrived at.

One of the interesting things about electrical accidents is that in terms of likelihood, it's not in the top 10. It is way off in the "other" category of accidents. Electrical injuries rarely happen. However if we narrow this to only look at fatalities, then it is number 7 in the work place. That being said, arc flash fatalities are an order of magnitude less than electrocutions. Caulder's numbers (published by ESFI) kind of take any kind of "burn" regardless of the source as an arc flash even when it is a burn due to a shock but even using this artificially high number he comes up with a number of about 0.1 arc flash injuries per 10,000 whereas he comes up with about 0.2 shock injuries per 10,000. However others have done statistics on what percentage of arc flash injureis are fatalities and it comes up with about 1 in 15. So if we use Caulder's artificially high "arc flash" number then the average arc flash fatality rate is about 1 in 1,500,000 per year. I maintain that it is actually far less if we remove the "burns = arc flash" requirement and cull out all the ones that are burned flesh in a shock incident, leaving only bonafide arc flash incidents but in the injury statistics it is hard to sort that way. So if we can maintain a likelihood of arc flash injury less than 1 in a million as a rough target for likelihood, then we're doing what we should be doing to avoid injuries. As an example the rate of arcing fault failures with disconnect switches is around 1 in 12,000,000 according to IEEE data on the subject. Breakers are closer to 1 in 100,000 but you have to dig deeper and look at the causes and conditions to see that it is actually closer to the 1 in a million number. These statistics are on par with most progressive industrial company standards for accident prevention across the board including fatalities and serious injuries other than electrical burns.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: PPE when connecting remote racking devices
PostPosted: Fri Oct 13, 2017 11:46 am 
Offline

Joined: Tue Apr 17, 2012 9:17 am
Posts: 8
We recently had a committee that went through all (or most) possible tasks related to electrical work and they came up with requirements for PPE, permits, etc. In the infinite wisdom of the committee, they determined that PPE is required to mount the remote racking device (presumably to unmount it as well, though this isn't explicitly stated). However, PPE is not required to actually rack in/out the breaker if you are out of the arc flash boundary. So in real life, an electrician could don PPE, mount the unit, take the PPE off, rack out the breaker outside the boundary, put the PPE back on, and then remove the unit. Incredibly impractical, obviously, but that's what you get when a committee of office workers puts together safe work practices.

So I'm in agreement with Paul that you are not interacting in such a way that the likelihood of an arc flash requires PPE. I don't feel that mounting a motor unit is significantly different from just standing in front of the switchgear. And we don't require PPE to stand in front of the gear (yet..).

All of this to say I don't think PPE is needed in this scenario, but if you (or your company) require it, you are not alone.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: PPE when connecting remote racking devices
PostPosted: Fri Oct 13, 2017 12:15 pm 
Offline
Arc Level

Joined: Tue Jan 13, 2009 5:00 pm
Posts: 429
Unplug or otherwise lock out the device to prevent any chance of it beginning to spin while attaching or removing.


Top
 Profile Send private message  
Reply with quote  
 Post subject: Re: PPE when connecting remote racking devices
PostPosted: Fri Oct 13, 2017 12:38 pm 
Offline

Joined: Mon May 21, 2012 5:00 pm
Posts: 8
Excellent suggestion. Most remote racking devices use a battery, however the power source can be disconnected while connecting the device.


Top
 Profile Send private message  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 1 guest


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:  
© 2017 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883