We’ll call this a hypothetical question. Say you are running a short circuit and arc flash study on a 50 year old building as part of a multi-building study. You discover you have about a half dozen branch panelboards that are over-dutied in this building. These are all 225A rated, 208Y/120V. Some are flush in block walls in finished areas. Breakers in these panels are 50 year old, long discontinued 10KAIC rated. The feeders are all protected with FRN or LPN fuses with no published series ratings available and no higher rated replacement breakers located. Artificially adding feeder length and/or reducing feeder sizes and fuses to reduce available fault current is possible but just as costly as changing the panels out.

You learn this building is supposed to be torn down within the next 5 years.

Now then switch hats, you’re the Owner and aware of the issue. Would you:

1. Do nothing other than proceed with arc flash labeling the building since the study is practically done. Afterall, this building is 50 years old and nothing has failed in all that time plus the feeders are protected with current limiting fuses so “‘yer’ prolly good. Yeehaw!”
2. Replace the panels with new with 22KAIC breakers even though some of them will be a bear and new guts and covers won’t fit in the old tubs and you’re tearing down the building in a few years. READ MORE