NFPA Journal®, November/December 2008
Selecting the proper personal protective equipment (PPE) is one of the steps you must take to protect electrical workers. In the 2009 edition of NFPA 70E®, Electrical Safety in the Workplace® , Section 130.7(C)(9) was revised to help you in that selection. You can now use Table 130.7(C)(9), formerly Table 130.7(C)(9)(a) in the 2004 edition, as a method for selecting PPE in lieu of the incident-energy analysis in Section 130.3(B)(2).
Some think they can do an incident-energy analysis, find the incident energy for the task, and use Table 130.7(C)(9) to select the PPE. If you choose to do an incident-energy analysis rather than using the tables, you cannot use Table 130.7(C)(9), Table 130.7(C)(10), or Table 130.7(C)(11).
Clarifying PPE use behind closed doors
To explain how the table was developed and why PPE is needed when equipment doors are closed and the equipment changes state, Fine Print Note (FPN) 1 was added to Section 130.7(C)(9). This FPN advises that doors do not provide enough protection to eliminate the need for PPE when the equipment is changing state—that is, being operated (either opening or closing).
As an example of this, look in the section of tasks for Metal Clad Switchgear 1 through 38 kV. Notice that the task "CB operation with the doors open" requires HRC 4 and task "CB operation with the doors closed" requires HRC 2. Some would argue that, if the doors are closed, there are no exposed live parts and that without exposed live parts, there is no arc flash protection boundary, so PPE is not required. Even those who do an incident-energy analysis and do not use the tables should think about this concept when considering the PPE for tasks involving operations with the doors closed.
Small changes increase safety in big ways
Table 130.7(C)(9) now includes tasks for performing infrared thermography for most equipment and working on equipment fed directly from a panel board or motor control center, both tasks that are performed frequently. Now that the standard defines these tasks, the table is even more useful. Any task not on the table requires an incident energy analysis, so the more tasks on the table, the less probable the need to do the analysis.
The table also increases the PPE rating for several of the medium-voltage tasks. For example, the task of racking E2 starters in and out with the doors closed was a HRC 2 task but now is an HRC 4 task. This change means that 40 calories per square centimeter PPE is now required rather than 8 calories per square centimeter PPE.
Also added to the table is a new equipment category, arc-resistant switchgear, which requires HRC 0 for most closed-door tasks. Remember that HRC 0 does not mean that no PPE is required. HRC 0 PPE is defined in Table 130.7(C)(10).
The notes to Table 130.7(C)(9) are also important and sometimes overlooked. Notes (d) and (e) were added to document the working distances. Now, not only do table users have to confirm the short circuit current and clearing time (Notes 1 through 4), but they also need to confirm that the working distance of the task meets Notes (d) and (e).
FPN 3 discusses the relationship between current and time and is a good reminder to use Notes 1 through 4. FPN 4 again emphasizes the importance of fault current and clearing time by requiring that they be documented. The specifics of how they are documented should be part of a written safety program and could go on the energized work permit. Notice the absence of time and current boundaries for the medium-voltage tasks in the table’s notes. In large power systems, checking the medium-voltage system to ensure that the incident energy level is below 40 calories per square centimeter may be prudent.
In summary, Table 130.7(C)(9) was introduced in the 2000 edition, and there were a few changes in the 2004 and 2009 editions. It is a good resource to use when selecting PPE if the resources to perform an incident energy analysis are not available. It is also a good idea for those doing an incident-energy analysis to compare their results with the table.
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