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.
