Arc Flash Labels

[patmcevoy]

Hi,

New to the forum. The 2009 NFPA 70E standards say equipment now needs labels saying the available incident energy and the proper PPE to wear when working on equipment. My firm has gotten involved with doing these arc flash calculations for our clients. When it comes to giving them labels for their MCC's or other equipment, we're not sure what to give them. Table 130.7 in 70E gives different categories for different tasks, which gives different levels of PPE for a piece of equipment. 70E also says to post a label on the equipment with the PPE required. So you could post a label with a category 4, but different tasks may only require a category 0 or 1. We're just going to post PPE labels for the worst case but wanted to know if anyone else has dealt with this.

Has anyone else had experience with this and how have you approached it?

Thanks,
Pat

 

[zog]

It seems you are confused. Are you actually doing an arc flash study or are you just making up labels from the 70E tables? (You might want to get the current 70E revision by the way)

You are not allowed to mix the tables and arc flash study results, one is rask based and one is hazard based. So if you do an actual analysis and identify the incident energy you put the PPE required based on that Ei on the label (Most do this in "stages" based on the PPE that will be available) and that is the required PPE, regardless of the task.

 

[patmcevoy]

Thanks for the response.

We've done a study. So we've been using information from that study and not the tables.

The reason I brought it up was because we have MCCs that have Dangerous energy levels on the line side of the main breaker. Everything after the main is a Category 1. We'd like to be able to allow them to work on equipment without putting on a suit.

We weren't sure if you can put different labels on different sections of MCC. Its not arc flash rated, so I see that as you have to take the worst case in the MCC on the line side of the main. (which would mean putting on a moon suit just to work on a small breaker far away from the main's line side)

Do you know of any kind of retrofit that you can put in a main breaker bucket to cover the line side and make the MCC the lower category?

Have you ever distinguished between different arc flash levels for different sections of MCC?

 

[DuraLabel]

patmcevoy: As Zog mentioned, you will want to pick up the latest NFPA 70E (2012). Below is the main section from the latest NFPA standards related to labeling. As Zog also mentioned, you should choose whether to perform analysis calculations or use the simplified tables in NFPA 130.7. It sounds like you have a completed analysis so the hard work is done.

Just fill out your label with the following requirements:

130.5(C) Equipment Labeling. Electrical equipment ... shall be field marked with a label containing all the following information:

1) Nominal system voltage
2) Arc flash boundary
3) At least one of the following:
a) Available incident energy and the corresponding working distance
b) Minimum arc rating of clothing
c) Required level of PPE
d) Highest Hazard/Risk category (HRC) for the equipment (simplified tables)
4) Date of analysis (If you are in Canada it's required, but good idea anywhere)

The breaker panelboard you are referring to and the MCC both must be labeled individually if they meet minimums for analysis by IEEE 1584. These minimums are 208V or greater and fed by a 125 kVA transformer or greater. Note: Your organization may wish to exceed the IEEE by lowering the minimums for transformers to 75 kVA to increase safety. However, that's not required.

If you already have the analysis information for both, you just need to label each individually with the information listed above from 130.5(C)

To avoid using the "moon suit," redesign your equipment so it can be safely de-energize before any inspection or work must be performed. Even still, you need to label it with an appropriate label to reminds workers to de-energize it before performing inspections or work.

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[jghrist]

You can put one label on the main MCC section and a different label on the rest of the MCC. It not clearly spelled out in NFPA 70E, but it depends on whether an arc started in the section being worked on could propogate to the line side of the main breaker where it would have to be cleared by an upstream device. If work is being done on the same vertical section as the main breaker, there may also be a possibility of something being dropped into energized parts on the source side of the main breaker.