Washington State L&I now requiring Arc Flash labels

[coulter]

...I believe that OSHA requires that electrical equipment be de-energized prior to working on it. I know that there are some instances that the equipment can be worked on energized by OSHA regulations as well....

That is real close to my understanding as well.

In our case, we are not working the medium voltage hot. However, my interpertation of the existing standards is that a voltage check of the bus to verify de-energized state and attaching a grounding spider are considered live work and require appropriate PPE

As for the 600V class, the only live work I am doing is troubleshooting controls inside MCC buckets, or installing a plug-in bucket. One does not have to be very far from the xfmr to have the PPE drop to Hazard class 2 or 3 - which isn't to bad.

As dlhoule rightly said, the management wants the down-time minimized. Even so, I've never had to attach a wire to a live 480V terminal. I'm not sure I can even think of a case where one would have to.

...If the person is truly "qualified" and had to work on a piece of energized equipment wouldn't he/she be asking about the arc-flash calc at that time prior to commencing with the work to assure that the proper PPE was utilized?....

I'd agree. I think asking those sort of questions is a mark of a truly qualified person. On the job I'm doing now, I have the techs asking and since I haven't seen the engineering firm calcs yet, I'm getting the field data and doing a calc. Are my calcs way conservative? Oh yeah.

...The requirement to label equipment in accordance with 110.16 seems to me to be an insult to the "Qualified Person". ....

Yes, I'd agree with that. The NEC required label seems pretty useless. As Jim Dungar said, "However regardless of what verbage is chosen, I would not want to explain why my label format did not correspond to a standard like ANSI Z535. " As I recall, that's the format we're using on the perminate labels. Again, as I recall, it has the approach boundaries, incident energy, Hazard Class - significantly more useful than the NEC required label.

carl

 

[jim dungar]

NFPA70E and the NEC only require the basic phrase "warning/danger arc-flash".

There is absolutely no OSHA or NFPA requirement anywhere to provide energy levels or PPE requirements on a lable.

Many companies treat arc flash labling the same as any other hazard. When was the last time you saw all of the MSDS information on a can of cleaner? How about PPE requirements for working with caustics?

My comment about ANSI Z535 is about how the label should look (size of letters and colors) not about the verbage.

 

[jcook980]

Coulter,

Yes, I'm talking primarily about non-industrial clients. Industrial clients understand the necessity of careful coordination and accurate fault studies. We just can't convince non-industrial clients that our design job is not really finished until just before construction is complete. As we all know, electrical engineering is always last to get started and finish on a design project and the budget is already blown by architectural, civil, structural and mechanical engineering by the time we get started.

We have been requiring the contractor to provide the short circuit and coordination study for the past couple of years. While some contractors haven't been too happy about it, it gets done and submitted for review. I think we'll also require an arc flash incident energy study on future projects.

Jim

 

[dlhoule]

Pete, Carl,

Even so, I've never had to attach a wire to a live 480V terminal. I'm not sure I can even think of a case where one would have to.

I can but we won't go there, because it would be an extremely unusual set of circumstances. However, in the process of troubleshooting if that live 480V terminal is there you need PPE. In actualitly you need the PPE to open the door to check for power or for troubleshooting. When the problem is found you can pull disconnect, lock out and make the repair.

Personally if I knew everything about a particular piece of equipment, I wouldn't be nearly as concerned about an arc flash. Has it ever been washed down with a water solution. Has a water pipe or roof leak ever gotten into the panel? Things like that.

If you have ever experienced an arc flash, you will know 2 things about them. #1..... when someone grabs you to try to find out if you are okay; it will scare you half to death because you won't see or hear them.

I suffered no burns or anything, but 60 amp combination starter was destroyed. I had a slight scrape on left arm from door blowing completely off. It was imbedded in a block wall about 12' away. It took close to an hour before I could see anything and about 6 hours to be able to hear a normal voice.

We had higher fault currents available at that time. I had just hooked up a replacement motor. Checked resistance and for grounds on load side of starter, closed the door and turned on disconnect to check rotation. Never got that far. As soon as disconnect was turned on it blew. Near as we could figure there must have been a carbon track across line side of starter. No fun.

Be very careful!

 

[don_resqcapt19]

Carl,

don_resqcapt19 wrote:
...With the major issue of getting "real" available fault current information from the utility, I would never sign my name to a calculation like that...
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Then I would ask, How do you meet 110.9 and 110.10? I'm not seeing a lot of difference.

The utilities will provide worst case fault current numbers, based on an infinite primary and the transformer. The use of those numbers will let you comply with 110.9 and .10. Yes, the equipment selected may be over kill for the real fault current, but it will be in compliance.

I've heard this plenty, but I don't know where it comes from. I could see it if one used the term, "could possibly", instead of "often". Incident energy is porportional to I^2t. so if the current dropped to 70%, the clearing time would have to double to keep the same incident energy (NFPA 70E, Annex D, 600V example) Checking the upper and lower bounds and setting appropriate protective settings is necessary and certainly part of the engineering.

You are correct that I have painted this issue with too broad of brush. For the most part this increase in incident energy would occur when the fault current was lowered enough so that the OCPD was operating in its short time or long time rating as opposed to the very short time or instantaneous range.
Don