This week’s question has been frequently discussed within the IEEE committee. I thought it would be interesting to see how others handle the situation.

During the course of performing an arc flash study, what if you discover equipment that has an inadequate interrupting or withstand rating. As far as arc flash warning labels and the arc flash study are concerned, you:

• Label the equipment and do nothing about the inadequacy (not in scope)
• Label the equipment AND list the inadequacy in the report
• Do not label the equipment AND list the inadequacy in the report
• Stop the study until the inadequacy is addressed
• Something else

I will include something in the executive summary, in bold letters, similar to this:

It should be noted that the following equipment and/or protective devices are rated below the available fault current at their location. A fault event affecting any of these could cause catastrophic damage to the equipment and risk the safety of personnel nearby. In addition, it could result in a lengthy power outage that could affect the facility's operation.

When doing a study, I consider myself as a messenger only. It is up to the facility management to decide how they act on the recommendations.

Forgive me for answering a question with another question but, having been to a number of facilities where no attention was paid to interrupting capacities, I feel this question begs another question. Consider the following scenarios.

Panel P-1 has bolted fault of 45 kA and has CB’s rated at 25 kAIC. One of these circuit breakers feed Panel P-2 where:

1) Bolted fault and arcing fault at P-2 are < 25kA.
2) Bolted fault at P-2 >25kA and arcing fault < 25kA.
3) Bolted fault and arcing fault at P-2 >25kA.

Some will label scenario 1 and list it as a deficiency in the report but scenarios 2 & 3 are a lot more dangerous. My answer is “it depends�.

Bob Ragsdale, P.E.

We've wrestled with this one too. I have heard of some that just stop at the first inadequate panel and won't label anything past it. Others only leave the label off the equipment that is inadequate and continue to label beyond. Not sure what the answer is but you are correct, it would be great to hear other opinions. The original poll question was great. Let's carry it further.

Thanks!

Supplemental label?

It is being discussed to supply an additional label to warn of the overdutied equipment. I know NEC 110.16 only requires arc-flash label, but NEC is usually minimal requirement.

We have come across this recently and wonder if there has been any further clarification on the matter in any code? Within SKM there is the option to run the study and ignor any over duty equipment and I assume it's there for a reason. Would appreciate any further calrification that further expalins this.

This is an issue that is still raised and there does not seem to be an industry consensus (which is why the question was asked some time ago)

The main issue that no one wants to point to is liability. If someone knows equipment was inadequate, there is a concern that completing the arc flash study and ignoring the inadequacy could come back to legally haunt them if something goes wrong. I think I recall a legal case to that effect – “but didn’t you know this when you performed the study?�

So, it does need acknowledged but the issue is how? Some will place a label with just a warning and no arc flash info, some place an arc flash label with a warning about the inadequacy, most will as a minimum document it in the report. As a minimum, it will likely upset the owner. From lots of experience, if you point out inadequate equipment to the owner (which you must do), they get all excited since now they own the liability and have a new item for their budget that does not have anything to do with process/production improvements.

Two thing I would NOT do is:
1) Skip labeling and not place anything on the equipment. That raises the question to the worker – did someone just forget this one?
2) Ignore the inadequacy.

Interested in what others have experienced?

Good luck!

I like to discuss the issue with the customer and get their input as how to handle it. At a minimum I will apply the arc flash label and identify the issue in the report.

One customer chose to place the arc flash hazard label but also had us apply a DANGER! label with a message along the lines of "NO PERSONNEL ACCESS PERMITTED WHILE ENERGIZED DUE TO INAPPROPRIATE SCCR". The panel then had to be de-energized before any doors were opened or covers removed until the issue was resolved.

If the issue was found on equipment in the process of being installed the label was applied but the installer was not given permission to energize, even for testing, until the issue was resolved.

Another question. When the majority say the label the equipment and list the under rated equipment in the report. How do yoiu label the equipment? Normal Arc Flash Label, under rated equipment label? Just to clarify what label you put on the equipment. We may be heading towards a Danger Label with the incident energy and boundry but stating no energized work permitted due to equipment rating. What are others thoughts on this approach?