How often should an Arc Flash Analysis Survey be updated?
NFPA 70E (2018) Article 130.5(G) "The incident energy analysis shall be updated when changes occur in the electrical distribution system that could affect the results of the analysis. The incident energy analysis shall also be reviewed for accuracy at intervals not to exceed 5 years."
The part that is most often going to give someone trouble here is “changes occur in the electrical distribution system that could affect the results of the analysis.”
What are the kinds of changes that might cause the analysis to change? Well, I’m not an electrical engineer, I am an electrician, so I cannot answer the question as well as others might be able to, but off the top of my head you might consider;
These are just off the top of my head. Another, unusual situation, can be when the utility themselves updates calculations using new software or technical approaches which can change such things as the supply fault current available, x/r ratios, or clearing times.
It is always a good idea to look at your system regularly (and five years might be a good value for your situation, or you might need to be doing audits more frequently based upon your facility or environment).
All good answers. A few more came to mind.
Another factor to consider on the subject of "when changes occur in the electrical distribution system that could affect the results of the analysis", is if in-plant loads have changed appreciably. Have you added or removed production equipment that could alter the system load, have equipment motors been replaced with larger/smaller motors, has power-factor correction capacitors been added, etc. Many things to consider!
I'd like to add emphasis to the excellent points Richard Gaudreau made. All changes in the electrical system must be reviewed and addressed, but reducing loads without resizing the protection is a problem often overlooked. Increasing loads can mean nuisance trips, but reducing loads can mean failure to trip before equipment damage or failure occurs.
I'd like to add a few things to consider as well. Changing breakers can change trip characteristics, which can change the greatest possible energy release at the panel, and change protection requirements. Adding motors to the system (including HVAC and generators) can cause additional energy to be introduced to the system in a fault condition.
Added panels in the system should always be evaluated for protection requirements as well, but the above are the major considerations downstream of the main distribution that come to mind.
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