Happy New Year! I hope 2013 has been a good year for you so far. We are ready to resume the Question of the Week and the first question of the year may be a bit controversial. It is a question that sparks frequent debate.

Electrical safety practices today are quite different than 10 to 15 years ago. Do you think the increase in electrical safety requirements, arc flash studies, labels, PPE requirements, energized electrical work permits etc. have been worth the cost/effort?

• Yes
• No
• Difficult to say

Your thoughts and opinions are welcome!

Yes, however I think the recent attention arc flash has received over the last decade has caused a renewed focus on electrical safety in general. I know many of the changes I’ve seen in how we do work have always been OSHA requirements that were just never really strictly followed such as the requirements for de-energization, justification for live work, live-dead-live testing, insulated tools and PPE for shock protection. [font=Tahoma][color=black]So I’d say a significant part of the benefit actually comes from a more stringent application of regulations that were already existing.[/color][/font]

A couple of diverging thoughts on this:

1) A significant part of the benefit of arc flash analysis has been a review and standardization of system protection methods and set points resulting in increased reliability and productivity and reduced fuse inventory. Work completed previous to arc flash studies was highly subjective to what ever engineer was doing it and often seemed like flavor of the week.

2) The general movement towards "safety programs on paper" is more expensive and time consuming than often portrayed. I participate in audit and safety program work and what gets dismissed as incidental to other work can actually take years to edit and implement; years of expensive time. And not unlike leeds programs with much of the focus on documentation, there exists risk that emphasis on documentation pulls effort and consideration away from the intended goals; we can easily become obsessed with bureaucratic safety while overlooking what otherwise might have caused our safety radar to go off. Finally, I have a concern about the number of pages of safety programs and how that plays into the attention span of perhaps a young worker; in zealous justification of their existence some of these safety writers have lost the audience: short is sweet.

Definately worth the cost & effort.
We're a mid sized industrial multi trade contractor employing 100 - 150 electricians at any given time working on new construction, expansions & maintenance primarilty in the pulp and paper, mining & petrochemical sectors. Our workers come to us from local union halls directly from an out of work list so we have no say in who we get or what their skill level is.
Since adopting NFPA 70E in 2007 we've seen a dramatic decrease in the number & severity of injuries and incidents related to energized electrical work - actually we haven't had any in 26 months. We've easily paid for the program, required training and the paperwork in decreased workers compensation costs. And because of our safety record we now have clients who would rather negotiate projects solely with us rather than put the work out to tender.

This question is difficult to answer. The correct answer is yes it is worth it. What makes it difficult is we are playing against "what if". We have a pretty good safety record and the cost of labels, studies, extra manpower, all the bells and whistles has been quite large. So from my view, we have taken a good safety record and now made it a "compliant" system with a good safety record. Was the cost worth it? We assume yes but we will never know - meaning hopefully we will never have a serious electrical accident or OSHA fines to know what we "bought" with our extra efforts. One side issue is the cost somewhat recurs. When NFPA has a new great idea, it adds a new burden such as changing labels to include their latest list of new information.

My answer is yes...

I completely agree with you but it's the NFPA's responsibility to share new and important information that may minimize hazards. Sometimes it takes years for an incident to occur and many years later for new standards to be implemented and finally enforced.

I am trying to find out what benefits are provided by insurance providers.
Is there a discount or something recognized by industrial insurance carriers that would offset part of the costs?

You would think so but the best way to find out is to ask your insurance agent. Let me know if you need a source for these Arc Flash labels.

The answer is Yes and the solutions become cheaper every year. Arc flash (and coordination) studies are now being implemented further upstream in the electric plant's lifecycle, and the improvements in hardware, while still expensive, are very impressive. In 20 years, the increased focus will all have been worth it as electrical systems will have more integrated arc flash safety

I agree with Gary B assesment

In particular "in zealous justification of their existence some of these safety writers have lost the audience". One of the biggest challenges I face in our safety program is getting through to the engineers and technicians working on the equipment. Teaching is a skill in itself and when your safety program is simply written to fullfill a requirement it ends up being written in such a way. Keeping a class of people engaged for any subject can be difficult but when it comes to their safety the stakes are raised.

You can have the best safety program in the world but if your people are falling asleep in class or simply going through the motions to get it into their training record - You Failed!

I had to think about this one for a while. The cost and effort sometimes seems like it is bordering on the extreme. I agree with Joe B. about the time you think you have it under control, the rules change. I have to say it is worth it however, because it would be difficult to explain about how someone was seriously injured or killed because we couldn't afford to do a thorough job.

I think it will be another ten years are so before the real benifits are shown. I would suspect there is only about a 50% compliance with the 70E/IEEE 1584. The people who are less likely to follow it are those who have less training and therefore are not as knowledgable and more likely to be injuried or killed.

I think there are two types of accidents:

one, things happen that you don't really have control over (Like a branch snapping off a tree in a tornado or a comet falling from the sky). For those no safety program is going to affect whether it happens or for the most part what damage is done.

two, everything else. The severity of the injury is dependant upon how aware we are. I know that really sounds obvious, but if you have workers just going through the motions to get their safety ticket punched then going out to work in a fog of unawareness, you will have more accidents that cause injury than if your workers are aware of their surroundings and conscientiously being proactive to avoid getting into a situation where they could be hurt.

Actually it's the other way around in most cases.

What you are seeing is expected. IEEE 1584 itself indicates that the calculated value is going to be sufficient combine with the specified clothing about 90%+ of the time in the event of an arc flash.

Most practitioners calculate this based on the worst case line-to-line value. However, roughly 90% of arcing faults are actually line-to-ground. Right from the beginning, the impedance of the return path to ground is usually not as good as the phase conductors. Also, in a 3 phase system, the voltage is significantly less (e.g. 277 V vs. 480 V). Not only that but IEEE 1584 itself estimates to the conservative side. If you have the standard there is a chart that shows you that the expected values of the arcing currents follow a "2 hump" pattern and the estimated value captures enough of both humps to have a confidence value of 95%. Obviously this is the extreme, NOT the average.

For example, the assymetrical fault current depends on the phase angle at the point in time when the fault occurred. This assymetrical fault current alone is responsible for producing anywhere between a value and 50% of that value depending on phase angle, with an average somewhere in between. The chance of having maximum assymetrical current is pretty darned small and makes for a dramatic difference in fault current.

On top of that, you are talking about 120/208 V systems. In those situations, the major issue is that arcing current really isn't a "sine wave". Instead, it's actually more like a square wave. When the current (not voltage) passes through zero, the arc extinguishes. As the source voltage increases again at a certain voltage, the arc will restrike and begin conducting again. This is not exact but that number tends to be right around 100-150 volts. In a 480 V, line-to-line fault, or higher, the arcing voltage tends to be not as critical. However on a 120/208 V system, it's hard to get the arc to ignite in the first place and there's not much heating and ionizing of the air going on in the arc column so it becomes harder and harder to reignite the arc, especially when all the gas in the area is expanding and creating a localized low pressure zone depleted of plasma and ions. So the tendency for 120/208 V systems is for the arc to self-extinguish. Once you get above about 250 Volts or so though, it doesn't self-extinguish anymore and continues to conduct nicely until power is externally removed.

Now, in a small number of cases, the arc does not necessarily extinguish for 120/208 V and that is what is critical. There isn't a whole lot of test data to go by. When it comes to safety, obviously it is necessary to err on the conservative side. So unless the probability of a fully developed arc flash is negligible, it is necessary to calculate the worst case scenario and live with it, knowing full well that it is highly unlikely to happen.

Now to your point specifically about 208/120 V systems. I wonder how this was calculated for your shop. In most cases I'm finding that even if I do the calculation and use conservative results, they are still well below 1.2 cal/cm^2. In my shop the only time we require anything more than "nonmeltable clothing" for 120/208 work is with a very large transformer with a very low impedance. Fortunately there are very, very few of those. Most practitioners have been somewhat abusing a part of IEEE 1584 which says that there should be little risk of arc flash with 125 kVA, 120/208 transformers. Jim Phillips is on the committee that is going to revise this section and the "125 kVA rule" will be revised down, but at least as of today, it's the best available information on what an acceptable PPE level is below that point. The tables in 70E on the other hand look at an extreme worst case example (25 kA fault current for 2 seconds at 240 volts) which is probably unrealistic for your situation and you'd be better off either using the IEEE "cutoff" rule or doing the actual calculation. If you do so, you will probably find yourself eliminating a 4 cal/cm^2 requirement, not that this is very onerous in the first place compared to my shop where we routinely have equipment that is more like 20 cal/cm^2.