Is it Sufficient to Use NFPA 70E Tables in Place of an Arc Flash Hazard Study?

The Arc Flash Hazard

Under all circumstances, it is necessary to protect the working personal from dangers associated with live electricity installations. For this reason and to ensure compliance with the OSHA regulations, Arc flash hazard and electric shock hazards need to be evaluated and studied for every facility having an electrical installation.

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What is an Arc Flash Hazard, and Why does it Occur?​

Electric arcs produce intense heat, sound blast and pressure waves. They have extremely high temperatures, radiate intense heat, can ignite cloths and cause severe burns that can be fatal. These arc flashovers occur due to dust on the conductor surface, condensation of vapor, corrosion of equipment parts and even accidental contact with live conductors.

What are the NFPA 70E Tables?

The 2012 NFPA 70E Article 130 tables specify:

· The safe distances or the arc flash boundaries that are to be followed when working on systems that have a voltage greater than 50 Volts.

· The personal protective equipment or PPEs that must be worn when working on systems that have a voltage greater than 50 Volts.

When the NFPA 70E Tables or the Arc Flash Hazard Study is Required?

Whenever any maintenance related or otherwise work has to be done on or near a live electrical installation that may not be brought into a safe working state for a number reasons, two things must be determined to ensure safety of employees.

The NFPA 70E Table Method​

The NFPA 70E table method can be applied to estimate the arc flash hazard in the a few steps that are discussed in detail here.

Limitations of the NFPA 70E Table Method

Testing NFPA 70E tables is usually the easiest, fastest and most straight forward method to enforce electrical safety standards, however there are some limitations to it.

IEEE 1584 Method for Arc Flash Hazard Analysis

The IEEE 1584 method of arc flash hazard analysis dictates that an arc flash study must be done in association with or follows in continuation of a short circuit analysis study and then a relay coordination study as discussed here comprehensively.

Benefits of Performing an Arc Flash Hazard Analysis​

An arc flash study by way of IEEE 1584 method and associated calculations, if done in place of using NFPA 70E tables will bring several benefits for the facility.

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