Arc Flash/Arc Blast PPE
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. Incident Energy PPE Category Cal/cm2 >1.2 to 4 1 >4 to 8 2 >8 to 25…
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Arc Flash/Arc Blast Hazard Labels
Arc flash/arc blast hazard labels inform personnel of the arc flash/arc blast hazard and the required PPE at each switchboard or arc flash/arc blast hazard location. The labels should present the following information: electrical hazard and danger symbols; arc flash/arc…
Arc Flash/Arc Blast Risk Assessment
The likelihood of an arc flash/arc blast event is dependent upon the type of activity being undertaken at the time. It is generally accepted that the greatest likelihood occurs when there is direct interaction by an individual on energised equipment…
Consequences of Arc Flash/Arc Blast
Arc faults are potentially fatal to any personnel in the vicinity. The intense heat of the arc flash/arc blast can severely burn human skin and ignite the clothing of anyone within several feet of the incident. Treatment for arc flash/arc…
Understanding Safe Approach Distance/SAD
The safe approach distance (SAD) is based on an “exclusion zone” principle. This principle defines an area around an exposed conductor into which no part of the person, mobile plant or object (other than approved insulated objects) may encroach unless…
Arc Flash/Arc Blast & Their Causes
An arc flash/arc blast is a dangerous electrical plasma explosion created by a short circuit through air that causes electric current to flash over from one exposed conductor to another or to ground. An arc flash/arc blast is characterised by…
Electrical Safety
The main considerations of safe working procedures on electrical equipment are to ensure safety of workers and safety of the general public. In addition to this, the continuity of supply, and the welfare of plant is important. To be able…
Fault Current
Power systems are effectively earthed by the neutral points being connected directly to earth. The only resistance being the inherent resistance of the connections and the earth itself. A system fault comprises either one or more phases being accidentally connected…
High Voltage Equipment Rating
Most high voltage distribution equipment has four basic ratings – service voltage; basic insulation level; rated current carrying capacity; and fault capacity. Service voltage The IEC sets standards for manufacturers to produce cables and switchgear for a preferred range of…
Substations
Substations, switchyards and switch rooms are hazardous areas but only become dangerous if procedures are not strictly followed. The safety of personnel is the paramount consideration in the operation of any power system. Substations are therefore designed to ensure that…