The importance of arc flash study and keeping it up to date

by Dec 11, 2018Electrical Safety

The importance of arc flash study and keeping it up to date


An incident energy (arc flash) study allows updating of the plant’s electrical plan(s), clear identification of each electrical equipment, targeting of protective equipment that are likely to falter during a short circuit and allows electricians, mechanics, refrigeration technicians and other qualified persons to use the right category or arc rating for personal protective equipment (PPE).

The incident energy study makes it possible to determine the incident energy level by simulating a short circuit current that is likely to go through every electrical diversion in the plant. The data obtained gives a precise estimate of the possible incident energy level. Thus, it is possible to produce warning labels for arc flash/ blast with the true energy levels while avoiding uselessly oversizing PPE, but still allowing for good protection and avoiding the severe burns caused by electrical arcs during live work.

In addition, this type of study can verify if protective equipment, such as circuit breakers or fused disconnects, are safe in their tripping time and are robust in handling of the available short-circuit currents. By doing this detailed study, it is also possible to recognize the area where the incident energy level is high and suggest corrective measures to reduce this energy level. Therefore, by reducing the electrical installation’s energy level, the required category of PPE could also be lowered. For example, when going from a category 2 to a category 1, a balaclava is no longer required.

An incident energy study has the advantage of verifying that the coordination of protective devices is adequate. A protective equipment can be a fuse or a breaker. It must always be the first to open as soon as a short-circuit occurs upstream and there should be no other protective equipment between the short-circuit and the protective equipment. In the case where there is a short-circuit and the protective equipment does not open the circuit, it is the protective equipment upstream of it that will have to open the circuit. This additional time for the circuit to open could cause damages to the equipment such as motors, heating elements, cables, etc. Where safety is concerned, the additional opening time can raise the incident energy level and be a source of fires. Thus, this study can target at-risk protective equipment and allow for their replacement before a short-circuit occurs.

An incident energy study must be performed every five years. This update also allows for keeping an up-to-date electrical plan of the plant. Furthermore, it can be quickly updated when an equipment is added or decommissioned. The business that had an incident energy study performed can also consult the firm that performed the study and ask what protective equipment is appropriate to protect the new equipment. The firm could rapidly run a simulation for the new equipment and suggest a sufficiently robust protective equipment in the event of a short-circuit without it being oversized.

After an incident energy study, the personnel in charge of safety can prioritize the electrical equipment that needs to be replaced, the areas where live work is strictly forbidden and the right choice of PPE to provide to qualified persons to do their jobs without oversizing them.


For more information on the incident energy study, you can consult the following blog on incident energy studies :

Don’t hesitate to contact us for more information!

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Intervention Prévention Inc.

Intervention Prévention concentrates its operations in the field of work safety, offering specialized services following Standards CSA Z462 – Workplace Electrical Safety, CSA Z460 – Control of Hazardous Energy: Lock-out and Other Methods, and CSA Z432 – Safeguarding of Machinery.


226-3275 rue de l’Industrie
Saint-Mathieu-de-Beloeil (Québec)
J3G 0M8