Arc Flash Study
An Arc Flash Hazard Analysis is a five-phase program that results in complete compliance with
NFPA 70E requirements. In the end you receive:
- Updated One-Line Electrical Drawings
- Arc Flash Hazard Analysis
- Mitigation and Corrective Action Recommendations
The step-by-step process is as follows:
Step 1: Data Collection
This is the largest part of the project and requires labor intensive efforts to gather all the information necessary to provide an accurate analysis. Mutliple pieces of data must be obtained from all electrical devices including transformer nameplate data, conductor sizes, conductor lengths, horsepower, breaker settings, manufacturer information on fuses/breakers, generator nameplates and utility service information. From this information we develop an updated electrical 1-line drawings.
Step 2: Hazard Analysis
We then take the data gathered and input the information into our Arc Flash Software. From this we produce a short circuit analysis and coordination study. The main goal of selective coordination is to isolate the faulted portion of the electrical circuit quickly while at the same time maintaining power to the remainder of the electrical system. The electrical system overcurrent protection must guard against short circuit and ground faults to ensure that the resulting damage is minimized while other parts of the system not directly involved with the fault are kept operational until other protective devices clear the fault.
Overcurrent protective devices, such as fuses and breakers, have time/current characteristics that determine the time it takes to clear the fault for a given value of fault current. Selectivity occurs when the device closest to the fault opens before the next device up-stream operates. For example, any fault on a branch circuit should open the branch circuit breaker rather than the feeder overcurrent protection. All faults on a feeder should open the feeder overcurrent protection rather than the service overcurrent protection. When selectivity occurs, the electrical system is considered to be coordinated. This isolates the system and prevents power loss to unaffected loads.
Step 3: Report Findings
The results of our findings are presented to you in person. We will notify you of inadequate interrupter ratings, improper coordination locations, list of arc flash hazards that can be mitigated to lower ratings and recommendations on device upgrades or changes to trip settings. You will then decide what, if any changes or corrective action needs to be taken and we will reflect these changes in the software.
Step 4: Arc Flash Hazard Labeling
We print and install arc flash labeling on all of the equipment contained in the scope of work. The arc flash labeling will reflect compliance with the NFPA 70E standards and contain information about voltage, arc flash boundaries and personal protective equipment (PPE). Click here to see a sample.
Step 5: Training
We provide you with proper training on-site to help you understand all of the aspects of the Arc Flash Hazard Study. Training is an essential part of any Arc Flash Study and covers NFPA 70E and OSHA requirements. We also teach you how to interpret the PPE required from the label and also what limited approach, restricted approach and prohibited approach mean.
Copyright 2012, Mitchell & Lindsey, LLC, Louisville, Kentucky
