How Do You Conduct an Arc Flash Analysis?

Arc flash incidents are one of the most deadly risks on the worksite, with arc flashes able to kill at distances of as little as 10 feet. More than three quarters of those questioned in an arc flash mitigation survey said reducing the risk of arc flash was an essential consideration, yet only 67% of respondents stated they had completed an analysis.

Why?

Perhaps a part of the problem is that there’s really no such thing as an ‘arc flash analysis’. Instead, this term has been created by combining ‘incident energy analysis’ and ‘arc flash risk assessment’… so which one should you be focusing on? Both.

Incident energy analysis should be an integral part of an arc flash risk assessment, and conducting this assessment is something that all businesses working onsite with electrical equipment should be prioritising. Under the European Council Directive 89/391/EEC, all employers have a legal responsibility to assess and identify the level of risk at work.

So how do you conduct an arc flash risk assessment?

There are two stages. The first stage covers the first 3 aspects of the Health & Safety Executive’s 5-step plan for undertaking a workplace risk assessment: identifying hazards, determining who is at risk and how, and considering the most effective precautions. This stage involves examining your electrical equipment type and voltage to generate a minimum arc rating in calories/cm2 and the overall arc flash boundary.

This can be done using one of two approved systems:

1. NFPA 70A (2015)

This system uses estimations made about the clearing time and fault current to create hazard category tables. This is the simplest of the two systems, and suggests the correct PPE that must be worn for the level of hazard (something that the other system does not), yet as it uses assumptions it is perhaps not the most accurate of the two options.

2. IEEE 1584-2002

This system is the more complex of the two, and while it doesn’t provide information about suitable arc flash workwear, it does offer more accurate risk calculations. It works by calculating the power and tripping data of the generator and components to calculate the arc fault current at each location, with separate information for each task and installation.

Once the hazard has been identified using one of the two systems, steps 4 and 5 of the HSE guidelines can be completed: recording findings of the assessment, and reviewing the assessment regularly, particularly in line with any changes made to the workplace.

Conducting an arc flash risk assessment and calculating incident energy can take time, yet it’s one of the most effective ways to minimise risk and ensure that all workers fully understand the type of personal protective equipment they should be wearing onsite.