Inspector is requiring everything to be labeled, I have a meter center with a main breaker that has a higher rating than the fault current from the Poco usually this is enough. I am not sure with the meter center main, feeder breakers in the meter center and the tenant panels ( main lug ) these are all series rated, do you still have to do calculations for the above breakers and if so what is the purpose of the factory series rating all of the equipment or does this article just require a label for what is already on the breaker.
Input on 110.24 Fault Current Labeling
- Thread starter KWH
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
This rule only applies to the service equipment, but it has nothing to do with the rating of the breaker. It requires that you show the amount of fault current that is available at that point on the system. You get the fault current information from the utility.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Let's be clear about two things. First, for any new building, you need to be able to show that every panel is rated to be able to handle the fault current that the system would impose on that panel. For smaller buildings, that is easy enough, since the service transformers are small and don't have a very high value for the available fault current. As you start getting into larger buildings, with higher rated service switchboards, you can't really be certain that all panels have a high enough fault rating without doing a formal short circuit study.
That said, however, the new requirement in the 2011 NEC for a label giving the available fault current value only applies to the main service panel, as Don mentioned.
That said, however, the new requirement in the 2011 NEC for a label giving the available fault current value only applies to the main service panel, as Don mentioned.
- Status