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Arc Flash is not just in plants

Arc Flash can and does occur in a variety of locations have you covered this risk

with staff?

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OK what is all the babble

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High Risk

• In the United States alone!On the average, every day in the U.S. five to ten people are sent to special burn units due to arc-flash burns. “There are one or two deaths per day from these multi-trauma events,”

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A large flash with burning results

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Not always the cause

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Big issues BIGGER Picture

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Regardless if you are

• Regardless if you are the investigator or the worker, arc flash incidents can and have occurred in a variety of workplaces, so what have you covered with staff and what do you know?

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Avoidance is not enough• The most common arc-flash hazard reduction methods

are: • Avoid the hazard area • Install arc-resistant switchgear • Add current-limiting devices • Reduce the relay time coordination settings • Improve protection schemes

• The energy produced by an arc-flash event is proportional to the voltage, current, and duration of the event (V • I • t). IEEE 1584-2002 concluded that arc time has a linear effect on incident energy. Therefore, reducing fault clearing times proportionately reduces arc flash.

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Before they started work did they cover the minimum safety knowledge

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Do you understandVoltage• NFPA 70E requires the voltage exposure to be identified as part of the shock hazard analysis

and that it is included on the energized electrical work permit and arc flash warning labels. This item documents the voltage for the specific equipment.

Equipment type• Depending on the equipment type, such as panel or switchgear, the IEEE 1584 arc flash

calculations may use different arc gaps, working distance and rate of decay of the incident energy as a function of distance. Each of these values affects the results and makes defining the correct equipment type very important.

Arc gap• An arc flash occurs when short-circuit current jumps across an air gap. The gap’s size affects

the arcing short-circuit current calculations and possibly also the duration. These values are used to calculate the prospective incident energy.

Bolted fault current• “Bolted” refers to a short circuit where the faulted conductors act as though they are solidly

connected or bolted together. This current is used to evaluate equipment’s interrupting or withstand rating and to calculate the arcing fault current.

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Do you understandEstimated arcing fault current• The arcing fault current is the current that flows across the arc gap. It is used for determining

the arcing time and incident energy and is influenced by variables, such as system grounding, the arc gap, and whether the arc flash occurs in equipment or in open air.

Arcing time• The duration of an arc flash is normally defined by the time it takes an upstream protective

device to clear the fault. Time-current curves from a coordination study and the estimated arcing short circuit are used to determine this value. (Editor’s note: Stay tuned for Jim Phillips’ article about coordination in the May issue.)

Arc flash boundary• The distance from an arc that it takes for the incident energy to fall to 1.2 cal/cm2 is known as

the arc flash boundary and is part of the calculation process. Defining this boundary is an NFPA 70E requirement for the arc flash hazard analysis.

Working distance• The working distance defines the distance from the arc flash where the incident energy is

calculated. It is normally considered where a worker’s head and torso would be located.

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Do you understand

Incident energy• The incident energy at a specific working distance defines

the severity of the arc flash and is used to determine the minimum protection for the worker.

PPE level• Although there sometimes is debate about using personal

protective equipment levels, it is still a common practice. Many in the industry will assign a level using numbers that typically correspond to a minimum arc-rating requirement for protective clothing and equipment of 4, 8, 25 and 40 cal/cm2 respectively

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Did you cover

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Risks and what is around the door

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The risks are closer than you think!

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Mines are not the only risk, think any site with electrical operations

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So before you enter before the work

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Everyone on site needs this talk