Standard Method for Remediation of Short Circuit Failures
Due to the number of assumptions and possible solutions, the method detailed here attempts to find the cheapest and least intrusive method of addressing underrated equipment that has failed short circuit. The solution that always works is equipment replacement, but that is rarely the most cost effective and requires down time to address. The purpose of this method is to ensure that the most effective solution is found for all failed equipment and can be completed even if the person doing it is not a subject matter expert. 1. Validate the short circuit rating with manufacturers The first step is to verify that the short circuit rating listed or assumed is accurate for all failed equipment. Assumptions are often made on equipment that does not have a short circuit rating listed. It is also not uncommon even on equipment with a listed short circuit rating to have variation depending on installation or to have unlabeled series ratings that were applied. Verifying the short circuit rating is best done by sending the nameplate information to the manufacturer. 2. Determine if series ratings can be applied Series rating equipment is often the most cost-effective solution for increasing the short circuit rating of equipment. All series ratings must be run through laboratory testing so working with the vendors of equipment is the best way to determine if there is the possibility of using them as a method for remediation. 3. Determine if current limiting fuses can be used Current limiting fuses are becoming a more reliable and commonly used technology, however there are limitations to their use. Current limiting fuses cannot be used in instances where there is “active” equipment downstream of the fuse as this can create racing conditions which slow down the current limiting fuse. These can most often be applied to mechanical equipment such as air conditioners, air compressors, heaters, etc. It is recommended to work with an engineer or firm with experience in arc flash remediation to determine if the application of current limiting fuses is appropriate. 4. Determine if equipment can be upgraded through component replacement The short circuit rating of equipment is most often based on the lowest rated component. It is often a possibility to replace these underrated components with higher rated components to increase the kASCR. Coordinate with the equipment manufacturer to determine if this is possible. 5. Determine equipment that must be replaced In instances where none of the above options will work, equipment replacement will be necessary. 6. Create remediation plan for all failures based on findings Generate a plan which includes the action to be taken for all failures with a timeframe of remediation and associated cost. This will allow for easy review, budgeting, and tracking of progress.
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