Mike Dolt Enterprises
Mike Dolt Enterprises
User: carnes51214, Location: Tennessee
Asked on: Thursday, April 14, 2011 at 4:57 pm EDT
Answered on: Tuesday, May 14, 2024 at 4:12 am EDT
Question: We are installing 480v A/c disconnects. From disconnect to A/C we are using sealtight flex. One side is concentric and the other is not. We do have a equipment grnd in flex. My question is being 480v do I still have to put a bond bushing on the concentric side even if I'm using a equipment grnd conductor. Or is it actually required on both ends because sealtight metallic is not suitable for equipment bonding as is emt and rigid.Another question on similiar lines is I have a 1 1/2 greenfield flex from panel with is no concentric knock out but to disconnect on bus duct is concentric. Do I need bond bushings on both ends or just the end with concentric knock outs.Also 480 volts.
Question 1
Yes, a bond bushing is still required on the concentric side of the sealtight flex, even though an equipment grounding conductor is used. According to Article 250.104(A), "Metallic armor, other than flexible metal conduit, enclosing electrical conductors shall be bonded at every point where the armor terminates or is interrupted." Sealtight flex is not considered suitable for equipment bonding, similar to EMT and rigid conduit.
Question 2: Bond bushings are required on both ends of the greenfield flex, even though the panel end does not have a concentric knockout. Article 250.92(E) states, "Flexible metal conduit shall be bonded where it terminates at both ends." Since the greenfield flex is a metallic enclosure, it must be bonded to provide a path for fault current to flow back to the source. Flag for review