ARC FLASH LABELING – WHAT TO DO AND WHAT NOT TO DO

In a previous article, “Arc Flash Labels – What You Need to Know”  I explained the information required on a compliant arc flash label. In this article, I discuss what you should and should not do when applying the labels on equipment and using the labels as guidance.

DO NOT use Arc Flash labels as permission to engage in live electrical work.

An arc flash label is a tool to be used as a hazard warning and an estimation of the risk should the worker engage in live electrical work. However, electrical work always needs to be justified according to NFPA 70E guidelines regardless of the presence of an arc flash label. Read my article “Justified” for more information on this topic.

DO utilize the worst-case scenario for incident energy and arc flash boundary.

The incident energy, PPE level, and arc flash boundary can vary on the same equipment depending on the conditions of the electrical system. For example, a panel may have differing risk levels under normal power than it does under emergency generator power. A proper arc flash risk assessment report will identify the differing levels of incident energy based on the different scenarios within the electrical system. However, the label should contain the worst case of all those scenarios.

DO NOT label with multiple working distances or PPE categories.

Working distances change based on the task being performed, and it’s not possible to include all the different tasks on one label. It is best practice to use a uniform working distance that is the same on all labels within a facility. This avoids confusion and makes the risk assessment more straightforward. In most cases, the working distance will default to 18 inches as this is the average distance from the live circuit parts to the worker’s chest and face assuming the worker is working with his arms outstretched.

Important Note: Care should be taken during the risk assessment process to consider what body parts might be closer than the working distance indicated on the label and take extra precaution. For example, if an arc flash label shows an incident energy of 8 cal/cm2 at a working distance of 18 inches, the worker must realize that the incident energy will be higher than 8 cal/cm2 for any part of the body closer than 18 inches to the live conductors. In this case, more consideration should be given to deenergizing the circuit or adding more protection to the parts of the body that are likely to be within 18 inches.

DO NOT include both the incident energy and arc flash PPE category on the same label. NFPA 70e allows the facility to use one of the following methods to estimate the risk of arc flash:

1. Incident Energy Analysis Method. This method calculates the incident energy in cal/cm2. This value is reflected on the arc flash label and PPE should be selected based on this value. Table 130.5(G) in NFPA 70E is used in this case.

2. Arc Flash PPE Category Method. This method utilizes tables 130.7(C)(15)(a) and 130.7(C)(15)(b) to identify the task and PPE category. The PPE Category is on the arc flash label, and Table 130.7(C)(15)(c) is then used to select PPE based on this.

Either the incident energy analysis method or the PPE category method can be used, but not both on the same piece of equipment. As a result, any arc flash label should contain just one of these values.

DO NOT color-code the labeling based on the incident energy or PPE category.

Some facilities prefer to color-code the labels based on risk level. For example: Red = PPE Level 4 (>40 cal/cm2), Yellow = PPE Level 3 (>25 cal/cm2) and so on. I advise against this because it can cause confusion and conflict with ANSI color-coding standards for Danger (Red), Warning (Orange) and Caution (Yellow). In addition, any changes in the NFPA Standard would likely render the color coding out of date.

Color-coding labels may create confusion or conflict with facility coding for equipment. Use the information on the label to assess risk rather than color-coding.

DO NOT place a label on each MCC bucket or Switchboard cubicle. Use one label for the entire unit.

Some facilities place an arc flash label on each bucket of an MCC and each cubicle of a switchboard. This is overkill and can add more confusion when equipment is already cluttered with too many labels. A worker who sees dozens of labels on the same piece of equipment might get confused as to which label is appropriate for risk assessment or might just simply ignore the warning. The proper procedure for MCC and Switchboards is to place one label on the switchboard.

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Two acceptable exceptions are as follows:
1) If the MCC or Switchboard has a main breaker section that is isolated from the remaining sections through a barrier, a separate label may be placed on the main breaker section and another label on the other sections. In this scenario, the main breaker section is protected by an upstream breaker or fuse and will likely have a different incident energy or PPE Category than the remaining sections which are protected by the main breaker in section 1.

2) Large MCCs or Switchboards with multiple sections may have a label on the top of each section, but not on the individual buckets or cubicles.

For equipment such as panelboards, breaker panels, transformers, disconnects, control panels, and ATS units, only one label should be visible on the front of the equipment to avoid clutter and confusion.

DO label the following equipment if it is over 50V:

Switchgear, switchboards, panelboards, transformers, breaker panels, ATS units, MCCs, control panels, disconnects, and any other equipment that is likely to be serviced are to be part of an arc flash risk assessment and should be labeled.

Please reach out to me with any questions or comments on this article or any of the other educational resources we have at www.mitchellandlindsey.com/resources.

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Thank you and be safe!
Bobby Lindsey – CESCP
Mitchell & Lindsey – President
M: (502) 836-4217
email: blindsey@mitchellandlindsey.com

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