The incident energy determined at each assessable location will fall within a defined arc flash/arc blast PPE category, as defined in the table below.

Arc flash/arc blast PPE selection

The selection of arc flash/arc blast PPE must be determined through a risk assessment which shall consider:

• the incident energy determined for the electrical equipment from an arc flash/arc blast hazard assessment;
• the proposed activity being undertaken on or within the vicinity of the electrical apparatus; and
• the condition of the equipment.

No person is permitted to enter the arc flash/arc blast boundary during switching, racking, electrical work, testing, cover removal, visual inspection or fault-finding activities unless they are wearing the appropriate PPE.

Where the arc flash/arc blast boundary extends beyond the access doors to the substation facility, appropriate barricades shall be erected controlling access when hazardous activities are being performed

As a minimum, when any of the high exposure activities referred to in the table above are performed within the arc flash/arc blast boundary, the appropriate level of PPE must be worn in accordance with the PPE Category determined for each assessable location. Additional requirements may be necessary depending upon the outcomes of a risk assessment.

The minimum PPE to be worn is depicted on the arc flash/arc blast label for the equipment, which is also described in the table and images below.

The general injury limits for the human body are:

• 2nd degree burns @ 79º Celsius for 0.1 sec.
• 3rd degree burns @ 93º Celsius for 0.1 sec.
• Eardrum damage @ 34.5 kPa
• Lung damage @ 83 kPa

Considering that the temperatures involved in an arc flash/arc blast can exceed 20,000º Celsius, and the associated noise levels can reach 180 dB, the consequences of arc flash/arc blast must not be underestimated.