Transportation Guy
Senior Member
- Location
- Williamsburg,VA
Good afternoon fellow professionals. We have an 800 amp service . Leaving the CT are 3 (parallel) sets of (4) 400MCM aluminum conductors in metal raceway. We need to bond these raceways. Based on 250.102 ( C) (1) our inspector says we can use a 1/0 copper. I dont agree. The chart says " Size of ungrounded conductor OR equivalent area for parallel conductors." Based on this, I dont use the largest ungrounded conductor to size this, I use the area of the ungrounded conductors since we are in parallel. By doing this, I exceed the chart (over 1750 kcmil because I have 9 ungrounded 400's which equal 3600 kcmil) The notes below the chart tell me I cannot be less than 12.5% of the equivalent area of ungrounded conductors but do not have to be larger than the largest ungrounded conductor. I calculate I need a 400kcmil as a bonding jumper for these raceways entering my service disconnect.
GO!!
GO!!