Step One - Discovery & Engineering - Details

As part of ArcSTOP's Step One, our trained AFLP experts conducts the following ten steps:

1. Collect system and installation data
The data needed for an arc flash hazard analysis is similar to that needed for a short circuit study. This will mean collecting all the data needed to build an up-to-date one-line diagram.

2. Determine Mode of Operation (Sequence of Operation)
Modes of operation are critical especially when working with Tie Breakers of multiple utility sources or with generators running with the grid. These are just a few of the modes that affect the available fault current for the study.

3. Determine Bolted Fault Currents
M. C. Dean, Inc. utilizes a number of tools, including SKM software to determine the Bolted Fault Currents from data gathered.

4.  Determine Arc Fault Currents
The Bolted Fault Currents calculated for each point represent the highest fault currents expected to flow to any short circuit.  In the case of an arc fault, the current flow will be less due to the added impedance of the arc. Predicting these lower levels is critical to the evaluation and providing worst-case arc fault hazards.

5.  Locate Protective Device Characteristics and Duration of Arcs
Use time-current curves of protective devices in each scenario, for fuses, breakers and relay-operated protective devices.

6. Document system voltages and classes of equipment
System Voltages affect bus gap which affects the arc energies.

7. Select Working Distances
This is the distance between the potential arc source and the worker's body and face.

8. Determine Incident Energy for all equipment
M. C. Dean, Inc.’s SKM software, along with the data collected, calculates the equation and solution based upon voltage level and the over current protective device and equipment. Measurement in cal/cm2 or joules/cm2.

9. Determine Flash-Protection boundary for all equipment
This calculation solves for a distance at an Incident Energy density of 1.2 cal/cm2.

10. Provide One-Line - Label all equipment

References

1. “Code of Federal Regulations” 29, Part 1900 to 1910.999, (2000)
2. “Standard for Electrical Safety in the Workplace”, NFPA70E, (2004)
3. “National Electrical Code” NFPA 70, (2005)